Torque sensor for an ebike system

Abstract

A torque sensor for a bicycle includes a coil. The torque sensor may include a support member disposed around an assembly of the bicycle such that the support member and the assembly of the bicycle are separated by an air gap. The torque sensor may also include an excitation coil supported by the support member; and a sensing coil supported by the support member at a distance away from the excitation coil in an axial direction of the support member. The excitation coil is configured to induce a voltage and / or current in the sensing coil via the assembly of the bicycle when the support member is disposed around the assembly of the bicycle. The induced voltage is related to a torque in the assembly.

Description

Torque Sensor for an Electric Bicycle System This application claims the benefit of U.S. Provisional Patent Application No. 63 / 286,370, filed on Dec. 6, 2021, the content of which is incorporated herein by reference in its entirety. This disclosure generally relates to sensors for bicycles, and more particularly to torque sensors for electric bicycles. A bicycle (e.g., an electric bicycle or e-bike) having a pedal-assisted electric motor may include sensors that monitor parameters at the bicycle. The parameters monitored may include, for example, an input torque at a crank arm assembly of the bicycle. Sensors that monitor the input torque at a bicycle crank arm assembly include, for example, strain gauges. However, strain gauges are expensive, incompatible with concentric motors, and do not allow for non-contact sensing. In one example, a torque sensor for a bicycle includes: a support that can be disposed around a device of the bicycle such that the support and the device of the bicycle are separated by an air gap. The torque sensor also includes: an excitation coil supported by the support; and a sensing coil supported by the support at a distance away from the excitation coil in an axial direction of the support. The excitation coil is configured to induce a voltage in the sensing coil via the device of the bicycle when the support is disposed around the device of the bicycle. The induced voltage is related to a torque in the device. In one example, the torque sensor further includes a shield that covers the excitation coil and the sensing coil such that the excitation coil and the sensing coil are encapsulated within the torque sensor. In one example, the shield is a first shield. The torque sensor further includes a second shield. The second shield at least partially covers the first shield. In one example, the bicycle is an electric bicycle and the device of the bicycle is a clutch mechanism of the electric bicycle. The support is a hollow cylinder that can be disposed around a portion of the clutch mechanism of the electric bicycle. In one example, the support includes a first groove and a second groove that extend circumferentially around an outer side of the support. The second groove is offset relative to the first groove in an axial direction of the support. The excitation coil is disposed in the first groove and the sensing coil is disposed in the second groove. In an example, the sensing coil is a first sensing coil, and the axial direction is a first axial direction. The support further includes a third groove that extends around the outer periphery of the support. The third groove is offset relative to the first groove along a second axial direction of the support. The second axial direction is opposite to the first axial direction of the support. The torque sensor further includes a second sensing coil that is disposed around and supported by the support. The second sensing coil is disposed in the third groove. In an example, the excitation coil is a first excitation coil. The support further includes a fourth groove that extends around the outer periphery of the support. The fourth groove is offset relative to the first groove along the first axial direction or the second axial direction. The torque sensor further includes a second excitation coil that is disposed around and supported by the support. The second excitation coil is disposed in the fourth groove. In an example, the first excitation coil and the first sensing coil form a first magnetic circuit, and the second excitation coil and the second sensing coil form a second magnetic circuit. The support has a first portion that houses a first part of the first magnetic circuit and a second portion that houses a second part of the second magnetic circuit. The torque sensor further includes a shield that separates the first portion of the support from the second portion of the support such that the first magnetic circuit is separated from the second magnetic circuit. The shield covers at least a portion of the support. In an example, the shield covers at least the first groove, the second groove, the third groove, and the fourth groove. The shield is made of a ferrite. In an example, the shield is a first shield. The torque sensor further includes a second shield that at least partially covers the first shield. The second shield is made of a non-ferromagnetic conductive material. In an example, the support is formed by a plurality of stacked printed circuit boards (PCBs). The excitation coil is formed on, in, or on and in a first printed circuit board (PCB) of the plurality of stacked PCBs, and the sensing coil is formed on, in, or on and in a second PCB of the plurality of stacked PCBs. In one example, a clutch mechanism for an electric bicycle includes an inner race, an outer race positioned around the inner race, and a torque sensor positioned around the inner race and the outer race such that the torque sensor and the outer race are separated by an air gap. The torque sensor is configured to measure a torque within the clutch mechanism. The torque sensor includes a housing that can be disposed around the outer race. The torque sensor also includes: an excitation coil disposed around and supported by the housing; a first sensing coil disposed at a first distance away from the excitation coil in a first axial direction of the housing and supported by the housing; and a second sensing coil disposed at a second distance away from the excitation coil in a second axial direction of the housing and supported by the housing. The second axial direction of the housing is opposite to the first axial direction of the housing. The excitation coil is configured to induce a voltage in the first sensing coil via the outer race. The induced voltage is related to a torque in the clutch mechanism. In one example, the outer race is the outer race, and the outer race is a shaft of a link of the electric bicycle. In one example, the excitation coil is a first excitation coil. The torque sensor further includes a second excitation coil disposed around and supported by the housing. The second excitation coil is offset relative to the first excitation coil in the second axial direction. In one example, the housing includes a first groove, a second groove, a third groove, and a fourth groove extending around an outer periphery of the housing. The first groove, the second groove, the third groove, and the fourth groove are offset from each other along the first axial direction of the housing. The first excitation coil is disposed in the first groove, the first sensing coil is disposed in the second groove, the second sensing coil is disposed in the third groove, and the second excitation coil is disposed in the fourth groove. In one example, the torque sensor further includes a shield that separates the first excitation coil and the first sensing coil from the second sensing coil and the second excitation coil, and covers the first groove, the second groove, the third groove, and the fourth groove. In one example, the shield is a first shield and is made of a first material. The torque sensor further includes a second shield. The second shield partially covers the first shield and is made of a second material. The second material is different from the first material. In one example, the voltage is a first voltage. The second excitation coil is configured to induce a second voltage in the second sensing coil via the outer race. The clutch mechanism further includes a processor configured to determine the torque in the clutch mechanism based on the induced first voltage and the induced second voltage. In one example, the processor is further configured to determine a difference between the sensed first voltage and the sensed second voltage. The processor is configured to determine the torque in the clutch mechanism based on the sensed first voltage and the sensed second voltage, including the processor being configured to determine the torque in the clutch mechanism based on the determined difference between the sensed first voltage and the sensed second voltage. In one example, a torque sensor for a bicycle includes a support member that is disposed around a clutch mechanism of the bicycle. The support member has a first portion and a second portion. The torque sensor also includes a first magnetic circuit that is supported by the first portion of the support member and disposed around the first portion of the support member. The first magnetic circuit includes a first excitation coil and a first sensing coil. The first excitation coil and the first sensing coil are offset from each other in an axial direction of the support member. The torque sensor also includes a second magnetic circuit that is supported by the second portion of the support member and disposed around the second portion of the support member. The second magnetic circuit includes a second excitation coil and a second sensing coil. The second excitation coil and the second sensing coil are offset from each other in the axial direction of the support member. The torque sensor also includes a first shield that separates the first portion of the support member from the second portion of the support member such that the first magnetic circuit is separated from the second magnetic circuit. The first shield covers at least the first excitation coil, the first sensing coil, the second excitation coil, and the second sensing coil. The torque sensor further includes a second shield that covers at least a portion of the first shield. The first excitation coil is configured to induce a voltage in the first sensing coil via a portion of the clutch mechanism when the support member is disposed around the clutch mechanism, and the second excitation coil is configured to induce a voltage in the second sensing coil via a portion of the clutch mechanism when the support member is disposed around the clutch mechanism. A torque in the clutch mechanism can be determined based on the sensed first voltage and the sensed second voltage. In one example, a torque sensor for a bicycle is provided. The torque sensor includes a coil. The coil is disposed around an entirety of a device of the bicycle. The coil is configured to sense a current and / or a voltage related to a torque in the device. The torque sensor may also include a support member that is disposed around or near the device of the bicycle. The coil can be supported by the support member. The device can be a clutch of a drive unit of the bicycle. The coil can be disposed around a seat ring of the clutch. A bicycle (e.g., an electric bicycle) is provided with an electric pedal assist motor capable of driving a link independently of a crank. Accurate, robust, and cost-effective torque sensing will be provided for controlling the electric bicycle. For proportional control of the electric pedal assist motor, a controller of the bicycle can vary an electric assist provided by the assist motor based on an amount of input torque generated by a rider at a crank assembly of the bicycle. For example, when the sensed input torque increases, the controller increases the electric assist provided by the assist motor, and when the sensed input torque decreases, the controller decreases the electric assist provided by the assist motor. For a bicycle drivetrain that utilizes electronic shifting, as the cadence increases, a controller that executes an automatic shifting algorithm initiates a gear shift. However, a rider of the bicycle may prefer to pedal at a lower cadence when riding at a leisurely pace and may prefer to pedal at a higher cadence when riding aggressively. Automatic cadence band adjustment can be provided based on a sensed riding situation. For example, the controller can increase a target cadence and thus a target cadence band for automatic shifting when high input torque is sensed, and decrease the target cadence and the target cadence band for automatic shifting when low input torque is sensed. A torque sensor according to the present disclosure can be incorporated within a roller bearing or sprag type rotary clutch mechanism of an electric bicycle system. For example, a sprag type rotary clutch mechanism can be disposed between a crank input (e.g., a crankshaft) of an electric bicycle system and a link output and / or a motor input. The sprag type rotary clutch mechanism transmits torque in a first rotational direction but rotates freely in a second rotational direction opposite to the first rotational direction. For example, a crank input via the sprag type rotary clutch mechanism drives a link output in the first rotational direction but rotates freely in the second rotational direction. When an assist motor of the electric bicycle system drives the link output such that the link output rotates faster than the crank input (e.g., by a rider of the bicycle pedaling), the sprag type rotary clutch mechanism slips or over-runs. The sprag type rotary clutch mechanism generates high strain, for example, in a hoop section of an outer race (e.g., a part of the link output) of the clutch mechanism, which is proportional to the reaction torque. The torque sensor of the present disclosure can measure the strain in the hoop section of the outer race by incorporating the outer race into a magnetic path of an electrical transformer and making the outer race of a material (e.g., an alloy) having linear or predictable magnetostrictive properties. These materials have a magnetic permeability that changes with the applied strain. The torque sensor includes a transformer having at least one excitation coil and at least one sensing coil. The at least one excitation coil is energized by an alternating current (AC) voltage, which induces an AC voltage in the at least one sensing coil. The at least one excitation coil and the at least one sensing coil are disposed around the outer race (e.g., a portion of the link output) such that a magnitude of the AC voltage induced in the at least one sensing coil is related to a torque, such as that reflected in a pawl type rotary clutch mechanism. Various embodiments of the present invention will be described herein with reference to the drawings. It will be understood that the drawings and descriptions set forth herein are for illustrative purposes only and do not limit the invention as defined by the appended claims and any and all equivalents thereof. For example, the terms "first" and "second", "front" and "rear", "left" and "right" are used for clarity and are not limiting terms. Furthermore, unless otherwise indicated, the terms refer to bicycle mechanisms conventionally mounted to a bicycle, and wherein the bicycle is oriented and used in a standard manner. It should be understood that the specific configurations of the frame, front wheel, rear wheel, drive chain, front brake, rear brake, and saddle, and the components illustrated are not limited to the disclosed embodiments. For example, although the front brake and rear brake are illustrated as hydraulic disc brakes, hydraulic rim brakes are contemplated and included within the scope of the present disclosure. Additionally, mechanical systems including mechanical rim brakes and mechanical disc brakes, as well as other electronic, hydraulic, pneumatic, and mechanical systems, or combinations thereof, such as suspension systems, are contemplated and included within the scope of the present disclosure. Referring now to the drawings, FIG. 1 generally illustrates a bicycle 100, and one or more system control devices 150 can be used with the bicycle to implement a bicycle control system using the torque sensors disclosed herein. In this example, the bicycle 100 can be a mountain bike. In some cases, the bicycle 100 can be an electric bicycle. The bicycle 100 has a frame 102, a handlebar 104 near a front end of the frame 102, and a seat or saddle 106 for supporting a rider above a top of the frame 102. The bicycle 100 also has a first or front wheel 108 carried by a front fork 110 of the frame 102 and supporting the front end of the frame 102. The bicycle 100 also has a second or rear wheel 112 supporting a rear end of the frame 102. The rear end of the frame 102 is connectable to a rear suspension assembly 114. The bicycle 100 also has a drive chain 116 having a crank assembly 118 that is operatively coupled via a chain 120 and a rear derailleur 122 to a rear sprocket 124 near a rotational axis of the rear wheel 112. The crank assembly 118 includes two cranks 123 and two pedals 125 that are respectively connected to the two cranks 123 on opposite sides of the frame 102 of the bicycle 100. In the example shown, the rear derailleur 122 includes a power source (e.g., a battery pack) and a motor and receives (e.g., wirelessly) instructions from a controller 126 (e.g., a shifter or a central controller) to shift gears on the rear sprocket 124, the controller being mounted, for example, to the handlebar 104 or the frame 102. In one embodiment, the rear derailleur 122 receives instructions from an electric bicycle control system 128 (e.g., which includes one or more processors, control circuitry, and / or a power source 130; a system control device 150) to shift gears on the rear sprocket 124. The rear derailleur 122 uses, for example, the power source and motor of the rear derailleur 122 to shift gears based on the received instructions. In one embodiment, the rear derailleur 122 is powered by a power source outside the rear derailleur 122. For example, the rear derailleur 122 is powered by the power source 130 (e.g., a battery pack) of the electric bicycle control system 128. In another embodiment, the rear derailleur 122 is also connected, for example, via a shifter cable to an input (e.g., a shifter) on the handlebar 104 and shifts gears on the rear sprocket 124 based on movement of the shifter (e.g., by the rider) and thus movement of the shifter cable. The battery pack 130 of the electric bicycle control system 128 is also supported by the frame 102 of the bicycle 100. For example, the battery pack 130 of the electric bicycle control system 128 is supported by a bottom tube 137 of the frame 102 of the bicycle 100. One or more components of the bicycle 100 (e.g., the controller 126) can be individually coupled to the power source 130 of the electric bicycle control system 128 via other wires. The battery pack 130 supplies power to a drive unit 138 (e.g., which includes an electric bicycle motor), which is operatively coupled to the crank assembly 118. In one embodiment, the drive unit 138 can also be powered by a separate battery pack to provide access to electric bicycle control when the battery pack 130 of the electric bicycle control system 128 is not attached to the bicycle 100. The drive unit 138 is mounted to the frame 102 of the bicycle 100. For example, the drive unit 138 is mounted to the frame 102 of the bicycle 100 using one or more bolts and threaded openings within the frame 102 of the bicycle 100. The drive unit 138 can be attached to the frame 102 in other ways. A crankshaft 140 (e.g., a crankshaft rod) travels through an opening in the drive unit 138 and connects two cranks 123 of the crank assembly 118. During operation, the rider rotates the two cranks 123 via the two pedals 125, rotating the crankshaft 140. The crank assembly 118 and / or the drive unit 138 can include sensors 141, which are configured to measure shaft rotation and force on the crankshaft 140. At least some of the sensors 141 can be disposed, for example, on at least one of the crankshaft 140 and / or the two cranks 123, adjacent to and / or within them. The crankshaft 140 drives an output ring (e.g., a chainring rod) of the drive unit 138 in a forward drive direction but not in a backward pedaling direction by using, for example, a one-way clutch (e.g., a sprag type rotary clutch mechanism) between the crankshaft 140 and the output ring. The shaft rotation and the measured force (e.g., by sensors) measured on the crankshaft 140 can be used to control an electric drive motor 146 (e.g., an auxiliary motor) of the drive unit 138. The auxiliary motor 146 can also directly or via the use of gears drive the rotation of the output ring. The output ring thus provides an output power to the drive chain 116, which is a combination of the rider input power and an output power of the auxiliary motor 146. Although the bicycle 100 illustrated in FIG. 1 is a mountain bicycle and may include a suspension assembly such as a shock-absorbing front fork, the specific embodiments and examples disclosed herein, as well as alternative embodiments and examples, are applicable to other types of bicycles. For example, the disclosed torque sensor can be used on road bicycles and bicycles with mechanical (e.g., cable, hydraulic, pneumatic, etc.) and non-mechanical (e.g., wired, wireless) drive systems. For example, the illustrated handlebar 104 relates to an aerodynamic handlebar configuration; however, the controller 126 and / or the bicycle control system can also be used with other types of handlebar assemblies, such as drop handlebars, bullhorn handlebars, riser handlebars, or any other type of bicycle handlebar. For example, the controller 126 can be a lever integrated with a drop handlebar configuration. Additionally, although the embodiments described herein illustrate manual control devices attached to the handlebars, one skilled in the art will recognize the possible locations of the control devices at other areas of a bicycle, such as positions through the frame 102 or other locations. The disclosed bicycle shift control method can also be implemented on other types of two-, three-, and four-wheel human-powered vehicles. The front and / or forward orientation of the bicycle 100 is indicated by the direction of arrow "A" in FIG. 1. Thus, a forward movement direction of the bicycle 100 is indicated by the direction of arrow A. The drive unit 138 can include internal electronics for controlling the operation of the assist motor 146, measuring the shaft input, measuring an inclination of the bicycle 100, measuring an acceleration of the bicycle 100, measuring a temperature of the bicycle 100, and / or reducing the voltage of the battery pack 130 of the electric bicycle control system 128 if a lower voltage is needed to accommodate and power an external device. For example, the internal electronics of the drive unit 138 can include one or more of the sensors 141 (e.g., one or more torque sensors, power meters, cadence sensors, wheel speed sensors, speed sensors, GPS sensors, inclination sensors, direction sensors, seat pressure sensors, mechanical switches, pedal force sensors, accelerometers, gyroscopes, lidar sensors, and / or other sensors). Additional, fewer, and / or different internal electronics can be provided within the drive unit 138. At least one of the sensors 141 can alternatively or additionally be located elsewhere on or in the bicycle 100 (e.g., an accelerometer on or in the rear suspension assembly 114). A controller of the drive unit 138 (e.g., a central control system or controller of an electric bicycle; a system control device 150) can be disposed on a housing of the drive unit 138 and arranged to route to the internal electronics of the drive unit 138. Alternatively or additionally (e.g., as part of the same housing), the electric bicycle controller can be supported by a housing identical to the power source 130. The electric bicycle controller can be made of a material through which a wireless control signal can penetrate. In one embodiment, the electric bicycle controller is arranged to route to the electric bicycle control system 128. The electric bicycle controller can control the power from the power source 130 to components on the bicycle 100 (such as, for example, the electric drive motor 146 of the drive unit 138). The electric bicycle controller can control the power to other and / or different components on the bicycle 100. The electric bicycle controller can send signals (e.g., commands) and / or receive data (e.g., commands and / or sensor data) to / from components on the bicycle 100, such as, for example, the rear derailleur 122, a suspension system, and / or a seat post assembly, to activate and / or control the components of the bicycle 100. In other embodiments, the electric bicycle controller can be located at other positions on the bicycle 100 (e.g., mounted on the handlebars 104), or alternatively, can be distributed among various components of the bicycle 100, with a routing of a communication link to accommodate the necessary signal and power paths. For example, a control unit 152 (e.g., acting as the electric bicycle controller; a system control device 150) can be mounted to the handlebars 104 to activate a motor of the rear derailleur 122 and operate the rear derailleur 122 to perform gear changes and gear selections. However, the control unit 152 and / or the electric bicycle controller can be located anywhere on the bicycle 100, or alternatively, can be distributed among various components of the bicycle 100, with a routing of a communication link to accommodate the necessary signal and power paths. In one example, the electric bicycle controller can be integrated with the rear derailleur 122 to transfer control commands between components. The control unit 152 and / or the electric bicycle controller can also be located at positions outside the bicycle 100, such as, for example, on a rider's wrist or in a jersey pocket. The communication link can include wires, can be wireless, or can be a combination thereof. The control unit 152 and / or the electric bicycle controller can include a processor, a communication device (e.g., a wireless communication device), a memory, and one or more communication interfaces. One of the rear derailleur 122 and / or the electric bicycle controller wirelessly actuates the rear derailleur 122 and / or a motor module of the electric drive motor 146, and operates the rear derailleur 122 to perform gear changes and gear selections. Additionally or alternatively, the controller of the rear derailleur 122 and / or the electric bicycle controller is configured to control gear shifting of a front gear changer. Data from the drive unit 138 (e.g., the sensor 141 of the drive unit 138) and / or the crank assembly 118 (e.g., the sensor 141 of the drive unit 138) can be transmitted to the electric bicycle controller. The data can be transmitted via one or more wired connections and / or wirelessly. For example, a crankshaft-based torque sensor generates data representative of the input torque and / or power applied to the crankshaft 140 and transmits the data to the electric bicycle controller. All communication between one or more system control devices 150 (e.g., the electric bicycle control system 128) of the bicycle 100 and each component is achieved through wired or wireless communication. There can be discrete control, where individual wires from an individual system control device 150 to the control of each component are controlled by the individual system control device 150 (e.g., a motor of the rear derailleur 122); or at least one of the system control devices 150 can use a controller area network (“CAN”) bus, which is configured to allow microcontrollers and devices to communicate with each other in the application. The data transmitted to the system control device 150 can be used to determine an amount of assistance provided by the electric drive motor 146 via the drive unit 138. Alternatively or additionally, the data transmitted to the system control device 150 can be used for automatic gear shifting. Referring to FIG. 2, in these examples, the rear derailleur 122 is shown as a wireless, electrically actuated rear derailleur that can be mounted to the frame 102 of the bicycle 100. The electric rear derailleur 122 has a base member 200 (e.g., a b-joint) that can be mounted to the frame 102. A link set 201 has two links, an outer link 202 and an inner link 204, which are pivotally connected to the base member 200. A movable member 206 (e.g., a p-joint) is connected to the link set 201. A chain guide assembly 208 (e.g., a cage) has a cage plate 210, which has a proximal end 212 pivotally connected to a portion of the movable member 206, as further described below. A motor module 214 is carried on the electric rear derailleur 122 and has a battery pack 216. The battery pack 216 supplies power to the motor module 214. In one example, as illustrated in FIG. 2, the motor module 214 is located in the base member 200. However, the motor module 214 can alternatively be located elsewhere, such as in the outer link 202 or the inner link 204, or in the movable member 206. The motor module 214 can include, but is not shown herein, a gear mechanism or a transmission system. As is known in the art, the motor module 214 and the gear mechanism can be coupled to the link set 201 to laterally move the cage plate 210 and thereby switch the chain 120 between the rear sprockets on the rear flywheel 124. The cage plate 210 also has a distal end 218 that carries a tensioner tooth or wheel 220 (e.g., a tensioner wheel). The tensioner wheel 220 also has teeth 222 that surround a circumference. The cage plate 210 is biased in a chain tension direction to maintain the tension in the chain 120. The chain guide assembly 208 can also include a second tooth or wheel, such as a guide wheel 224, that is disposed closer to the proximal end 212 of the cage plate 210 and the movable member 206. In operation, the chain 120 is arranged to route around a rear sprocket of the rear flywheel 124. An upper section of the chain 120 extends forward to a link 143 of the crank assembly 118 and is arranged to route around the link 143. A lower section of the chain 120 returns from the link 143 to the tensioner wheel 220 and then is routed forward to the guide wheel 224. The guide wheel 224 guides the chain 120 to the rear flywheel 124. The lateral movement of the cage plate 210, the tensioner wheel 220, and the guide wheel 224 can determine the lateral position of the chain 120 for alignment with a selected rear sprocket of the rear flywheel 124. The battery pack 216 can be replaced by an alternative power supply or power source and can operate other electrical components of the bicycle 100 within a linked system. The battery pack 216 or other power supply can also be located at other positions, such as attached to the frame 102. Additionally, multiple power supplies can be provided, which can supply power to the electrical components of the system, including the rear derailleur 122, such as the electric drive motor 146, either collectively or individually. However, in this example, the battery pack 216 is configured to be directly attached to the rear derailleur 122 and only provides power to the components of the rear derailleur 122. Data transmitted to the system control device 150 may include torque data from one or more sensors 141 (e.g., from the drive unit 138 and / or the crank assembly 118). For example, the torque data may correspond to the torque input by the rider at the crank 123 and may be used by the system control device 150 to control an amount of assistance provided by the electric drive motor 146 (e.g., proportional control for the electric drive motor 146) and / or as an input for controlling an automatic shifting mode of the bicycle 100. Figures 3-6 illustrate a first example of a torque sensor that may generate such torque data for use by, for example, the system control device 150. Referring to FIGS. 3 and 4, the crankshaft 140 drives an output ring 300 (e.g., a chainring output and motor input) of the drive unit 138 in a forward drive direction but not in a backward pedaling direction by using, for example, a one-way clutch mechanism 302 (e.g., a clutch mechanism) of the type of a sprag clutch between the crankshaft 140 and an output ring 300. The crankshaft 140 serves as an inner race of the clutch mechanism 302, and the output ring 300 serves as an outer race of the clutch mechanism 302. The crankshaft 140 and the output ring 300 are cylindrical in shape. For example, the crankshaft 140 is a solid cylinder, and the output ring 300 is a hollow cylinder. In one embodiment, the crankshaft 140 is also a hollow cylinder. The crankshaft 140 may be made of any number of materials, including, for example, steel or an aluminum alloy. Referring to FIGS. 4-6, the clutch mechanism 302 includes elements 304 disposed between the crankshaft 140 and the output ring 300. The elements 304 are, for example, sprag elements (e.g., cam-shaped wedges). Referring to FIG. 6, the clutch mechanism 302 may include any number of sprag elements 304 within a volume disposed between the crankshaft 140 and the output ring 300. For example, as shown in FIG. 6, the clutch mechanism 302 may include eighteen sprag elements 304 disposed around the crankshaft 140. In other embodiments, the clutch mechanism 302 includes more or fewer sprag elements 304. The sprag elements 304 may be equally spaced apart from each other around the crankshaft 140. Each of the anti-rotation pad elements 304 (e.g., along a longitudinal axis of an individual anti-rotation pad element 304) is angled relative to a radius of a crankshaft 140 passing through the centroid of the individual anti-rotation pad element 304. In one embodiment, each of the anti-rotation pad elements 304 is angled at the same angle. This orientation of the anti-rotation pad elements 304 relative to the crankshaft 140 and the output ring 300 provides that the crankshaft 140 and the output ring 300 rotate together (e.g., lock as a solid shaft) when the crankshaft 140 rotates in a first rotation direction D1. When the crankshaft 140 rotates in a second rotation direction D2 opposite to the first rotation direction D1, or the output ring 300 rotates faster than the crankshaft 140 (e.g., via an electric drive motor 146), the anti-rotation pad elements 304 slide or overrun, allowing the crankshaft 140 to rotate relative to the output ring 300, or vice versa. The clutch mechanism 302 generates high strain in the hoop section of the outer race of the clutch mechanism 302 (e.g., the output ring 300). The strain in the hoop section is proportional to the reaction torque. Thus, by measuring the strain in the hoop section of the output ring 300, the input torque at the crank 123 can be determined, for example. The strain in the hoop section of the output ring 300 can be measured, for example, by incorporating the output ring 300 into a magnetic path of an electrical transformer. The output ring 300, as the outer race of the clutch mechanism 302, for example, is made of a material (e.g., an alloy) having linear or predictable magnetostrictive properties. The magnetic permeability of these materials changes with the applied strain. The electrical transformer includes at least one excitation coil energized by an AC voltage, which induces an AC voltage in at least one sensing coil (e.g., at least one sensing coil). The amplitude of the AC voltage induced in the at least one sensing coil is proportional to a reaction torque in the clutch mechanism 302. Figures 3-6 illustrate a first example of a torque sensor 306 that measures the strain in the hoop section of the output ring 300 in this way. Referring to Figures 3-5, the torque sensor 306 includes a support 308 (e.g., a spool) that supports an excitation coil 310 and at least one sensing coil 312 (e.g., two sensing coils). The support 308 is fixedly positioned relative to a portion of the vehicle frame 102, and both the crankshaft 140 and the output ring 300 are rotatable relative to the support 308. However, in one embodiment, the support 308 can rotate with the output ring 300 and rotate relative to a portion of the vehicle frame 102. The support member 308 can be of any number of shapes and can be made of any number of different materials. For example, the support member 308 can be a hollow cylinder and can be made of a ceramic or a glass fiber reinforced resin (e.g., G10 - FR4 glass fiber epoxy laminate). Other shapes and / or materials can also be provided. For example, the support member 308 can be made of another material having a low magnetic permeability (e.g., close to 1.0), such as, for example, a plastic with or without glass fiber reinforcement (e.g., nylon, acetal, and polyether ether ketone (peek)). As shown in FIGS. 3 - 5, the support member 308 can be a single component that supports the excitation coil 310 and at least one sensing coil 312. In another embodiment, the support member 308 can be formed of a plurality of separate components, for example, each fixedly positioned relative to the frame 102. For example, the support member 308 can include three separate components that support the excitation coil 310 and two sensing coils 312. The support member 308 can include grooves 314 in which the excitation coil 310 and at least one sensing coil 312 can be respectively disposed. In the example of FIGS. 3 - 6, the torque sensor 306 includes one excitation coil 310 and two sensing coils 312 (e.g., a total of three coils), and three grooves 314 corresponding to the total of three coils 310, 312. The torque sensor 306 can include more or fewer sensing coils 312, and thus more or fewer corresponding grooves 314. The grooves 314 extend circumferentially around the support member 308. The excitation coil 310 can be made of any number of materials. For example, the excitation coil 310 can be made of magnet wire (e.g., copper or aluminum magnet wire). The magnet wire can, for example, be wound around the support member 308 any number of times within a corresponding groove 314 to form the excitation coil 310. For example, the magnet wire can be wound around the support member 308 50 times (e.g., 50 turns) to form the excitation coil 310. In other embodiments, the magnet wire is wound around the support member 308 more or fewer times to form the excitation coil 310. The two sensing coils 312 can be made of any number of materials, for example. For example, the two sensing coils 312 can be made of magnet wire (e.g., copper or aluminum magnet wire). For example, the magnet wire can be wound around the support 308 any number of times in the corresponding grooves 314 to form the two sensing coils 312. For example, in each of the corresponding grooves 314, the magnet wire can be wound around the support 308 50 times (e.g., 50 turns) to form an individual sensing coil 312. In other embodiments, the magnet wire is wound around the support 308 more or fewer times to form the sensing coils 312, respectively. In one embodiment, each of the two sensing coils 312 has a number of turns different from that of the excitation coil 310 (e.g., 50 turns), but the two sensing coils 312 have the same number of turns (e.g., 60 turns). Varying the ratio of the number of turns of the excitation coil 310 relative to the number of turns of the two sensing coils 312 allows varying the signal gain. Referring to FIGS. 4 and 5, the excitation coil 310 and the two sensing coils 312 are concentrically wound around the support 308 and thus concentrically positioned around, for example, the output ring 300. A first sensing coil 312a of the two sensing coils 312 is positioned on a maximum hoop strain region of the clutch mechanism 302. For example, a first groove 314a of the grooves 314 and the first sensing coil 312a are positioned on the anti-rotation pad element 304. In one embodiment, as shown in FIGS. 4 and 5, the first sensing coil 312a is axially centered relative to the anti-rotation pad elements 304. In another embodiment, the first sensing coil 312a overlaps the anti-rotation pad elements 304 but is not axially centered relative to the anti-rotation pad elements 304. The excitation coil 310 is positioned adjacent to the maximum hoop strain region of the clutch mechanism 302. For example, a second groove 314b of the grooves 314 and the excitation coil 310 are adjacent to the first groove 314a and the first sensing coil 312a (e.g., offset 1 mm, 2 mm, 3 mm, or 4 mm in an axial direction relative to the first groove 314a and the first sensing coil 312a). One of the two sensing coils 312, a second sensing coil 312b, is positioned adjacent to the excitation coil 310. For example, one of the grooves 314, a third groove 314c, and the second sensing coil 312b are adjacent to the excitation coil 310 (e.g., offset 1 mm, 2 mm, 3 mm, or 4 mm in an axial direction relative to the second groove 314b and the excitation coil 310), such that the second sensing coil 312b and the first sensing coil 312a, and the corresponding grooves 314c and 314a are respectively on opposite sides of the excitation coil 310 and the second groove 314b. In one embodiment, as shown in FIGS. 4 and 5, the third groove 314c and the second sensing coil 312b are offset relative to the second groove 314b and the excitation coil 310 by the same amount as the first groove 314a and the first sensing coil 312a are offset relative to the second groove 314b and the excitation coil 310, although in the opposite direction. As illustrated in one embodiment presented in FIG. 4B, the torque sensor 306A may also include a shield 303. The shield 303 may include an outer shield 307 and an inner shield 307. The shield is further described herein in connection with FIGS. 29 - 30 and the discussion throughout the text. Referring again to FIGS. 4 - 6, the torque sensor 306 is electrically connected to electronics to power the excitation coil 310 and process signals at the sensing coils 312. FIGS. 7 - 9 show examples of such electronics (e.g., circuits) that may be included and / or used with the torque sensor 306 of this embodiment and / or other torque sensors (see FIGS. 22 - 30). FIG. 7 shows an example of an excitation coil driver circuit 700 that can power the excitation coil 310. The electronics may include multiple excitation coil driver circuits 700, e.g., corresponding to the number of excitation coils of a particular torque sensor (e.g., two excitation coil driver circuits for the torque sensors of FIGS. 22 - 30). The excitation coil driver circuit 700 generates an AC voltage. The generated AC voltage can be sinusoidal, square, triangular, or other shapes. In the example shown in FIG. 7, the excitation coil driver circuit 700 includes an oscillator circuit 702, a power amplifier 704, and an H - bridge circuit 706. The excitation coil driver circuit 700 may include additional, fewer, and / or different circuits, and / or may include additional, fewer, and / or different electronic components. For example, the excitation coil driver circuit 700 may include a resonant oscillator, such as a Colpitts oscillator circuit. In the example shown in FIG. 7, oscillator circuit 702 is a crystal oscillator circuit. The crystal oscillator circuit 702 can generate, for example, a digital square wave, but another circuit that generates a different periodic signal can be used. The digital square wave controls switches such as H-bridge circuit 706 so that a voltage across excitation coil 310 is switched. The crystal oscillator circuit 702 that can provide frequency stability includes a crystal 708 (e.g., a piezoelectric material such as quartz), an inverting amplifier 710 (e.g., two inverting amplifiers), capacitors 712 (e.g., two capacitors), and resistors 714 (e.g., two resistors). An output of the crystal oscillator circuit 702 is, for example, a digital square wave signal having an output frequency. The output frequency can depend on the crystal used and how the crystal is manufactured (e.g., shape and size). The output of crystal oscillator circuit 702 is input to power amplifier 704. This input to the power amplifier 704 (e.g., the output of crystal oscillator circuit 702) is, for example, a low-power input, and the power amplifier 704 generates a high-current drive input for the transistors of H-bridge circuit 706. In the example shown in FIG. 7, power amplifier 704 is a gate driver. For example, gate driver 704 can include a level shifter combined with an amplifier. Gate driver 704 is, for example, an interface between the digital output of crystal oscillator circuit 702 (e.g., a square wave output of crystal oscillator circuit 702) and the switches of H-bridge circuit 706. Gate driver 704 interfaces the digital output of crystal oscillator circuit 702 to a voltage level suitable for controlling the switches of H-bridge circuit 706. In the example shown in FIG. 7, H-bridge circuit 706 includes four power MOSFETs 716, but other switches can be used. The digital square wave signal output from, for example, crystal oscillator circuit 702 controls the four power MOSFETs 716 via, for example, gate driver 704, which switch the voltage across excitation coil 310. The controlled power MOSFETs 716 switch the voltage across excitation coil 310 so that: when the square wave is in a high state, one end of excitation coil 310 is connected to a positive voltage, and the other end of excitation coil 310 is connected to ground; and when the square wave is in a low state, the polarity is switched so that that end of excitation coil 310 is connected to ground, and the other end of excitation coil 310 is connected to the positive voltage. H-bridge circuit 706 and thus an output of crystal oscillator circuit 702 is an alternating current for excitation coil 310. An alternating current at the excitation coil 310 induces an alternating current in each of the two sensing coils 312. In one embodiment, the outputs of the two sensing coils 312 are directly connected to a microcontroller analog-to-digital converter (ADC) or to a discrete ADC. Alternatively, as shown in the examples of FIGS. 8 and 9, the outputs of the two sensing coils 312 can first be conditioned by analog circuits such as, for example, a clamping circuit and / or a peak detector circuit. As shown in the example of FIG. 8, the signals from each of the first sensing coil 312a and the second sensing coil 312b can be conditioned independently. For example, a first signal conditioning circuit 800a electrically connected to the first sensing coil 312a includes a first clamping circuit 802a and a first peak detector circuit 804a, and a second signal conditioning circuit 800b electrically connected to the second sensing coil 312b includes a second clamping circuit 802b and a second peak detector circuit 804b. The induced voltage in each of the two sensing coils 312a, 312b has a peak-to-peak voltage proportional to a torque in a measured element (e.g., output loop 300). Each of the signal conditioning circuits 800a, 800b conditions the individual induced alternating current (e.g., an individual high-frequency AC signal) to a low-frequency DC signal that can be sampled by an ADC. The clamping circuits 802a, 802b adjust the induced alternating current voltages at the sensing coils 312a, 312b to be entirely positive such that a minimum voltage is at approximately ground voltage. By shifting the signal above ground voltage, the sensitivity can be doubled (e.g., since measuring an actual peak-to-peak voltage). The peak detector circuits 804a, 804b perform a voltage ratcheting function that charges individual capacitors 806a, 806b to a highest observed voltage and slowly discharges the individual capacitors. The outputs of the peak detector circuits 804a, 804b can then be sampled by the corresponding ADC. Within an individual peak detector circuit 804a, 804b, a combination of a capacitor and a resistor voltage defines a bandwidth of the individual peak detector circuits 804a, 804b. In one embodiment, the excitation coil 310 can operate at 90 kHz, while the individual peak detector circuits 804a, 804b are sensitive to approximately 100 Hz, although other frequencies can be used. Compared to the measurement signal on the second sensing coil 312b (e.g., outside the high strain region of the outer race of the clutch mechanism 302), the measurement signal on the first sensing coil 312a in the high strain region of the outer race of the clutch mechanism 302 can change similarly with torque, although with opposite signs. A microcontroller (e.g., the system controller 150 or another controller on the bicycle 100) can receive the measurement signals (e.g., the converted signals from the ADC) and determine a difference between these measurement signals (e.g., a differential voltage). The differential voltage varies with torque but can cancel out any sensor offset or drift caused by the thermal expansion of the components of the clutch mechanism 302 and / or the torque sensor 306. The microcontroller can determine a reaction torque based on the differential voltage. For example, the reaction torque can be determined based on a predetermined function (e.g., experimentally determined), using the differential voltage as an input. In the example shown in FIG. 9, the signals from the first sensing coil 312a and the second sensing coil 312b can be adjusted together such that only the differential voltage is measured in a single ADS input. The first sensing coil 312a and the second sensing coil 312b are connected in series, and the outputs of the first sensing coil 312a and the second sensing coil 312b are adjusted together. For example, a single signal conditioning circuit 900 electrically connected to the first sensing coil 312a and the second sensing coil 312b includes a single clamping circuit 902 and a single peak detector circuit 904. The signal conditioning circuits 800a, 800b, 900 can include more, different, and / or additional components. For example, before the ADC, the measured signals can be further amplified using, for example, an operational amplifier. Additionally, the noise in the measured signals can be reduced using a low-pass filter before the ADC. Other components can be included. The drive unit 138 and / or the frame 102 of the bicycle 100 can support the torque sensor 306, the circuit driving the torque sensor 306, and the circuit processing the signals measured by the torque sensor 306. Figures 10-16 are graphs showing exemplary signals discussed above with reference to the torque sensor 306 and the circuit of FIGS. 7-9. FIG. 10 is a graph showing an example of input torque versus time. FIGS. 11 and 12 corresponding to the input torque of FIG. 10 show how the voltage induced in the sensing coil is affected by the input torque. For example, FIGS. 11 and 12 are graphs showing the output voltage versus time at a first sensing coil (e.g., the first sensing coil 312a on the pawl pad element 304) and at a second sensing coil (e.g., the second sensing coil 312b), respectively. As illustrated in FIG. 11, the peak-to-peak voltage decreases as the applied torque at the first sensing coil increases, and as illustrated in FIG. 12, the peak-to-peak voltage increases as the applied torque at the second sensing coil increases. FIG. 13 is a graph showing an example of the voltage versus time in an excitation coil (e.g., the excitation coil 310). The voltage in the excitation coil is constant with torque. FIG. 14 is a graph showing an example of the voltage (e.g., the measured voltage) in a sensing coil (e.g., the first sensing coil 312a or the second sensing coil 312b). FIG. 15 is a graph showing an example of the measured voltage after clamping (e.g., at the output of one of the first clamping circuit 802a or the second clamping circuit 802b). FIG. 16 is a graph showing an example of the measured voltage after clamping and peak detection (e.g., at the output of one of the first peak detector circuit 804a or the second peak detector circuit 804b and before input to an ADC). Other torques, voltages, and / or frequencies may be provided. Other configurations of the torque sensor may be provided. For example, FIGS. 17-21 illustrate a second example of a torque sensor 1700 that can generate torque data for use, for example, by the system control device 150. The torque sensor 1700 of FIGS. 17-21 is different from the torque sensor 306 shown in FIGS. 3-6 in that the excitation coil 1702 and the sensing coil 1704 are each formed in a printed circuit board (PCB). The excitation coil 1702 and the sensing coil 1704 are disposed around the output ring 300. In other words, the torque sensor 1700 does not include a support (e.g., a spool) separate from the body such as the PCB. Referring to FIG. 21, each of the PCBs includes any number of layers 1708. For example, the PCB 1706 shown in FIG. 21 includes six layers 1708 a-f. Each of the six layers 1708 a-f is cylindrically configured and includes a substrate 1710 and one or more traces 1712 (e.g., a copper trace) disposed on one side of the substrate 1710. For example, each of the six layers 1708 a-f includes a continuous trace 1712 that wraps around the cylindrically configured substrate 1710 a plurality of times (e.g., eight or ten times) to form windings of the individual coils 1702, 1704. Each of the six layers 1708 a-f may have the same number of windings, and each of the coils 1702, 1704 may have the same number of windings. Other configurations may be provided. The trace 1712 of a first layer 1708a among the six layers winds inwards from an input end 1713 of one of the individual coils 1702, 1704 to a first through-hole 1714 of the first layer 1708a. When the six layers 1708 are stacked to form the individual coils 1702, 1704, the first through-hole 1714 of the first layer 1708a communicates with a first through-hole 1716 of a second layer 1708b among the six layers. The trace 1712 of the second layer 1708b winds outwards from the first through-hole 1716 to a second through-hole 1718 of the second layer 1708b. When stacking the six layers 1708, the second through-hole 1718 of the second layer 1708b communicates with a second through-hole 1720 of a third layer 1708c among the six layers. The trace 1712 of the third layer 1708c winds inwards from the second through-hole 1720 of the third layer 1708c to a third through-hole 1722 of the third layer 1708c. When stacking the six layers 1708, the third through-hole 1722 of the third layer 1708c communicates with a third through-hole 1724 of a fourth layer 1708d among the six layers. The trace 1712 of the fourth layer 1708d winds outwards from the third through-hole 1724 of the fourth layer 1708d to a fourth through-hole 1726 of the fourth layer 1708d. When stacking the six layers 1708, the fourth through-hole 1726 of the fourth layer 1708d communicates with a fourth through-hole 1728 of a fifth layer 1708e among the six layers. The trace 1712 of the fifth layer 1708e winds inwards from the fourth through-hole 1728 of the fifth layer 1708e to a fifth through-hole 1730 of the fifth layer 1708e. When stacking the six layers 1708, the fifth through-hole 1730 of the fifth layer 1708e communicates with a fifth through-hole 1732 of a sixth layer 1708f among the six layers. The trace 1712 of the sixth layer 1708f winds outwards from the fifth through-hole 1732 of the sixth layer 1708f to an output end 1734 of one of the individual coils 1702, 1704. Other configurations may be provided. Figures 22 - 31 illustrate a drive system 2200 of a third example including a torque sensor 2202, which can generate torque data for use by, for example, the system control device 150. Referring to Figures 22 - 24, the drive system 2200 includes a drive unit 2204 that can be mounted to a frame of a bicycle (e.g., the frame 102 of the bicycle 100). For example, the drive unit 2204 can be mounted to the frame of the bicycle via a support structure 2206 (e.g., a frame portion) of the drive system 2200. Referring to FIG. 23, the support structure 2206 may include a first support member 2206a and a second support member 2206b. The first support member 2206a and the second support member 2206b may support the drive unit 2204 on opposite sides of the drive unit 2204, respectively. Referring to FIG. 24, the first support member 2206a and the second support member 2206b of the support structure 2206 may include recessed portions 2208 (e.g., cylindrical recessed portions) in which opposite sides of the drive unit 2204 may be respectively positioned. Referring to FIGS. 22 and 23, when opposite sides of the drive unit 2204 are respectively disposed within the cylindrical recessed portions 2208 of the first support member 2206a and the second support member 2206b, the first support member 2206a and the second support member 2206b may be attached to the bicycle frame such that the drive unit 2204 is confined within the support structure 2206 and the support structure 2206 is attached to the bicycle. In one embodiment, the bicycle frame (e.g., the frame 102 of the bicycle 100) may include a hollow cylindrical portion (e.g., a bottom bracket housing) through which the drive unit 2204 extends, and the first support member 2206a and the second support member 2206b are attached to opposite sides of the hollow cylindrical portion of the bicycle frame. The support structure 2206 may be attached to the bicycle frame in any number of ways, including, for example, using bolts and openings in the support structure 2206 and the bicycle frame. Referring to FIG. 23, the support structure 2206 may include any number of openings 2210 through which bolts may extend to attach the support structure 2206 and thus the drive unit 2204 to the bicycle frame via corresponding openings (e.g., threaded openings) in the bicycle frame. As shown in the example of FIG. 23, the first support member 2206a and the second support member 2206b may each include one or more openings 2210a adjacent to the respective cylindrical recessed portions 2208. The support structure 2206 may include any number of attachment features 2212 through which one or more of the openings 2210 extend, such as, for example, lugs, flanges, and extensions. The drive unit 2204 may be attached to the bicycle frame in any number of other ways. For example, the support structure 2206 may be welded to the bicycle frame. Other configurations may be provided. Referring to FIGS. 22 and 25, the drive system 2200 also includes a crank assembly 2214. The crank assembly 2214 includes a crankshaft 2216 (e.g., a crankshaft rod) that travels through an opening of the drive unit 2204 and connects two cranks 2218 of the crank assembly 2214 on opposite sides of the crankshaft 2216. During operation, the rider rotates the two cranks 2218 and rotates the crankshaft rod 2216 via two pedals respectively attached to the two cranks 2218. Referring to FIG. 25, the crank assembly 2214 and / or the drive unit 2204 may include a torque sensor 2202. The torque sensor 2202 may be disposed around the crankshaft 2216 (e.g., serving as an inner race of a clutch mechanism 2222 of the drive unit 2204) or an outer ring 2224 (e.g., an output ring) of a clutch mechanism 2222. The crankshaft 2216 drives the output ring 2224 (e.g., a chain ring input and a motor input) of the drive unit 2204 in a forward drive direction but not in a backward pedaling direction by using, for example, a one-way clutch mechanism 2226 (e.g., a ratchet type rotary clutch mechanism) between the crankshaft 2216 and the output ring 2224. Referring to FIG. 25, the torque sensor 2202 may be disposed coaxially with the output ring 2224 of the clutch mechanism 2222 and around the output ring 2224. The drive unit 2204 includes a housing 2228 that supports and / or encloses components of the drive system 2200. The torque sensor 2202 may be attached to the housing 2228 of the drive unit 2204 such that the torque sensor 2202 is stable (e.g., fixedly positioned) relative to the housing 2228 of the drive unit 2204. The torque sensor 2202 may be attached to the housing 2228 of the drive unit 2204 such that the torque sensor 2202 and the output ring 2224 of the clutch mechanism 2222 are separated by a radial gap 2230 (see FIGS. 29 and 30). The torque sensor 2202 may be attached to the housing 2228 of the drive unit 2204 in any number of ways. For example, the torque sensor 2202 may be attached to the housing 2228 of the drive unit 2204 by using one or more fasteners (e.g., one or more screws or bolts through screw holes). Other attachment configurations of the torque sensor 2202 within the drive unit 2204 may be provided. The drive unit 2204 may include more or additional components. For example, referring to FIG. 25, the housing 2228 of the drive unit 2204 may house a rotor 2232 that rotates with the crankshaft 2216, and a stator 2234 supported by the housing 2228. The stator 2234 may drive the rotor 2232 attached to the crankshaft 2216. The drive unit 2204 may also include a reducer 2236 (e.g., including one or more gears) coupled to the output ring 2224. The output ring 2224 may be, for example, a link shaft 2238 (e.g., the link 143 of the crank assembly 118). The drive unit 2204 may include bearings and / or bushings. For example, the drive unit 2204 may include a bushing 2240 for a stop washer type rotary clutch mechanism 2226, a bushing 2242 for the crankshaft 2216, and a bearing 2244 for the link shaft 2238. Additional, fewer, and / or different bushings and / or bearings may be provided. The drive unit 2204 may include more, fewer, and / or different components. Referring to FIGS. 29 and 30, the torque sensor 2202 includes a support 2250 (e.g., a housing). The support 2250 includes, for example, a first support 2252 (e.g., a first part of the support 2250) and a second support 2254 (e.g., a second part of the support 2250). The first support 2252 and the second support 2254 may be separated from each other in, for example, an axial direction of the support 2250. Each of the first support 2252 and the second support 2254 may be configured as, for example, a hollow cylinder (e.g., a coil carrier, a spool), but other configurations may be provided. In one embodiment, the first support 2252 and the second support 2254 are connected to each other. The first support 2252 and the second support 2254 may be made of any number of materials, including, for example, a plastic. The first support 2252 and / or the second support 2254 may be made of a different material. The torque sensor 2202 includes a first magnetic circuit 2256 (e.g., a measurement circuit) and a second magnetic circuit 2258 (e.g., a reference circuit). The first support 2252 supports (e.g., houses) the first magnetic circuit 2256, and the second support 2254 supports (e.g., houses) the second magnetic circuit 2258. For example, the first support 2252 includes a first groove 2260 and a second groove 2262 that extend into the first support 2252 and extend around an outer side 2264 of the first support 2252. The second groove 2262 is offset relative to the first groove 2260 in a first axial direction 2266 of the torque sensor 2202. The first magnetic circuit 2256 includes a first excitation coil 2268 and a first sensing coil 2270 respectively disposed in a first groove 2260 and a second groove 2262. In one embodiment, the first excitation coil 2268 is disposed in the second groove 2262, and the first sensing coil 2270 is disposed in the first groove 2260. The first excitation coil 2268 can be made of any number of materials. For example, the first excitation coil 2268 can be made of magnetic wire (such as copper or aluminum magnetic wire). The magnetic wire of the first excitation coil 2268 can be wound around the first support member 2252 in the first groove 2260, for example, any number of times to form the first excitation coil 2268. For example, the magnetic wire of the first excitation coil 2268 can be wound around the first support member 2252 50 times (for example, 50 turns) to form the first excitation coil 2268. In other embodiments, the magnetic wire of the first excitation coil 2268 is wound around the first support member 2252 more or fewer times to form the first excitation coil 2268. The first sensing coil 2270 can be made of any number of materials. For example, the first sensing coil 2270 can be made of magnetic wire (such as copper or aluminum magnetic wire). The magnetic wire can be wound around the first support member 2252 in the second groove 2262, for example, any number of times to form the first sensing coil 2270. For example, the magnetic wire of the first sensing coil 2270 can be wound around the first support member 2252 50 times (for example, 50 turns) to form the first sensing coil 2270. In other embodiments, the magnetic wire is wound around the first support member 2252 more or fewer times to form the first sensing coil 2270. In one embodiment, the first sensing coil 2270 has a number of turns (for example, 60 turns) different from that of the first excitation coil 2268 (for example, 50 turns). Varying a ratio of the number of turns of the first excitation coil 2268 relative to the number of turns of the first sensing coil 2270 allows varying the signal gain. When a rider applies torque to the crankshaft rod 2216 through the pedal and stop wheel pad type rotary clutch mechanism 2226, radial stress is applied to the crankshaft rod 2216. The crankshaft rod 2216 can be made of a magnetostrictive material having a magnetic resistance that changes with a physical deformation amount experienced by the crankshaft rod 2216. The torque sensor 2202 can be positioned relative to the crankshaft rod 2216, and a physical geometry of the crankshaft rod 2216 can be optimized to facilitate generating a high stress zone (HSZ) between, for example, the first excitation coil 2268 and the first sensing coil 2270. The HSZ is subjected to higher stress than other parts of an outer surface of the crankshaft rod 2216, such that the torque applied by the rider is more easily measured. The permeability of many materials can be temperature-dependent, such that when the drive unit 2204 begins to heat up due to use or cool down due to other factors, the zero torque point (ZTP) may drift. It may be difficult to obtain a stable torque measurement over time in such drifting situations. The second support 2254 includes a third groove 2272 and a fourth groove 2274 that extend into the second support 2254 and extend circumferentially around an outer side 2276 of the second support 2254. The third groove 2272 is offset relative to the first groove 2260 in a second axial direction 2278 of the torque sensor 2202. The second axial direction 2278 of the torque sensor 2202 is opposite to the first axial direction 2266 of the torque sensor 2202. The fourth groove 2274 is offset relative to the third groove 2272 in the second axial direction 2278 of the torque sensor 2202 or in the first axial direction 2266 of the torque sensor 2202 (e.g., the second axial direction 2278 of the torque sensor 2202). The second magnetic circuit 2258 includes a second sensing coil 2280 and a second excitation coil 2282 disposed in the third groove 2272 and the fourth groove 2274, respectively. In one embodiment, the second sensing coil 2280 is disposed in the fourth groove 2274, and the second excitation coil 2282 is disposed in the third groove 2272. The second excitation coil 2282 can be made of any number of materials. For example, the second excitation coil 2282 can be made of magnet wire (such as copper or aluminum magnet wire). The magnet wire of the second excitation coil 2282 can be wound around the second support 2254, for example, any number of times in the fourth groove 2260 to form the second excitation coil 2282. For example, the magnet wire of the second excitation coil 2282 can be wound around the second support 2254 50 times (e.g., 50 turns) to form the second excitation coil 2282. In other embodiments, the magnet wire of the second excitation coil 2282 is wound around the second support 2254 more or fewer times to form the second excitation coil 2282. The second sensing coil 2280 can be made of any number of materials. For example, the second sensing coil 2280 can be made of magnet wire (such as copper or aluminum magnet wire). The magnet wire can, for example, be wound around the second support member 2254 any number of times within the third groove 2272 to form the second sensing coil 2280. For example, the magnet wire of the second sensing coil 2280 can be wound around the second support member 2254 50 times (e.g., 50 turns) to form the second sensing coil 2280. In other embodiments, the magnet wire is wound around the second support member 2254 more or fewer times to form the second sensing coil 2280. In one embodiment, the second sensing coil 2280 has a number of turns (e.g., 60 turns) different from that of the second excitation coil 2282 (e.g., 50 turns). Varying a ratio of the number of turns of the second excitation coil 2282 relative to the number of turns of the second sensing coil 2280 allows varying the signal gain. In one embodiment, the support member 2250 is a single support member, in which the first groove 2260, the second groove 2262, and the third groove 2272 extend into and extend circumferentially around it. In this embodiment, the first excitation coil 2268 can be disposed within the first groove 2260, the first sensing coil 2270 can be disposed within the second groove 2262, and the second sensing coil 2280 can be disposed within the third groove 2272. The torque sensor 2202 is positioned relative to the crankshaft 2216 such that a low stress zone (LSZ) (e.g., relative to the HSZ) is positioned between the second sensing coil 2280 of the torque sensor 2202 and an excitation coil (e.g., the second excitation coil 2282). In the LSZ of the crankshaft 2216, a relative change in magnetic reluctance can be lower in magnitude than in the HSZ. This provides a stable reference where ZTP varies with temperature. When the materials in the torque sensor heat or cool at a similar rate to each other, the permeabilities of the first magnetic circuit 2256 and the second magnetic circuit 2258 change at a similar rate and in the same direction. A processor, either in the torque sensor 2202 or outside the torque sensor (e.g., of the bicycle 100), can generate torque data for use by the system control device 150, e.g., based on an amplitude difference between signals from the first sensing coil 2270 and the second sensing coil 2280 (e.g., calculated by the processor). Referring to FIGS. 29 and 30, the torque sensor 2202 includes an inner shield 2284 (e.g., a first shield) that covers at least a portion of the support member 2250. In the embodiment shown in FIGS. 29 and 30, for example, the inner shield 2284 includes a first inner shield 2286, a second inner shield 2288 separated from the first inner shield 2286, and a spacer 2290 disposed between the first support member 2252 and the second support member 2254. The spacer 2290 thus separates the first support member 2252 from the second support member 2254, and thus separates the first magnetic circuit 2256 and the second magnetic circuit 2258. In this embodiment, the first inner shield 2286 covers at least a portion of the first support member 2252 (e.g., at least an outer circumferential surface and an outer end of the first support member 2252), and the second inner shield 2288 covers at least a portion of the second support member 2254 (e.g., at least an outer circumferential surface and an outer end of the second support member 2254). For example, the first inner shield 2286 covers at least the first groove 2260 and the second groove 2262 in the first support member 2252, and the second inner shield 2288 covers at least the third groove 2272 and the fourth groove 2274 in the second support member 2254. Thus, the first inner shield 2286 encapsulates the first excitation coil 2268 and the first sensing coil 2270 within the first support member 2252, and the second inner shield 2288 encapsulates the second excitation coil 2282 and the second sensing coil 2280 within the second support member 2254. The inner shield 2284 guides magnetic flux lines by adding a return path of a highly ferromagnetic material (e.g., a low magnetic resistance return path), which helps to provide a closed magnetic circuit. Adding a low magnetic resistance return path significantly increases the flux flowing in the first magnetic circuit 2256 and the second magnetic circuit 2258 respectively, and the coupling, both of which contribute to an increased sensing amplitude and thus an increased measurement sensitivity. The inner shield 2284 (e.g., the first inner shield 2286 and the second inner shield 2288) can be made of any number of materials (e.g., a first shield material). For example, the first inner shield 2286 and the second inner shield 2288 can be made of the same material, such as a material having a high magnetic permeability and a low conductivity (e.g., a ferrite). In one embodiment, different ferrites are used for the first inner shield 2286 and the second inner shield 2288 respectively. The spacer 2290 can be made of any number of different materials. For example, the spacer 2290 can be made of the same material as the first inner shield 2286 and the second inner shield 2288 (e.g., the first shield material). In one embodiment, the spacer 2290 is made of a material different from the first inner shield 2286 and / or the second inner shield 2288. For example, the spacer 2290 can be made of a plastic. The magnetic permeability of the first shield material can be as high as possible to provide a lowest magnetic resistance path for the magnetic flux. When an AC magnetic field enters a good conductor, eddy currents are generated. The magnetic field of the eddy currents is opposite to an applied magnetic field (e.g., generated by the first excitation coil 2268 and / or the second excitation coil 2282), thus weakening the applied magnetic field. Accordingly, the magnetic field shield material can have a low conductivity. In one embodiment, the inner shield 2284 is a single component that covers at least a portion of the support member 2250. In one embodiment, the inner shield 2284 covers at least a portion of the first support member 2252 and at least a portion of the second support member 2254. This inner shield 2284 separates the second support member 2254 from the first support member 2252, and thus the second magnetic path 2258 from the first magnetic path 2256. A cross-section of this inner shield 2284 can have a comb-like structure. In another embodiment, where the support member 2250 is a single component that supports the first excitation coil 2268, the first sensing coil 2270, and the second sensing coil 2280; the inner shield 2284 is a single component that covers at least a portion of the support member 2250 and encapsulates the first excitation coil 2268, the first sensing coil 2270, and the second sensing coil 2280 within the torque sensor 2202. The first magnetic path 2256 causes the flux to pass through the HSZ, and the second magnetic path 2258 causes the flux to pass through the LSZ. The chambers of the first magnetic path 2256 and the second magnetic path 2258 (e.g., two chambers) are isolated from each other (e.g., by the spacer 2290), and the measurement sensitivity is thus increased while the measurement error is reduced. Some of the magnetic flux, traveling in loops, crosses both the HSZ and the LSZ. This can cause a measurement signal (e.g., from the first sensing coil 2270) and a reference signal (e.g., from the second sensing coil 2280) to be correlated, which reduces the measurement sensitivity and causes the reference signal to change more with the applied rider torque. Referring to FIGS. 29 and 30, the torque sensor 2202 may also include an outer shield 2292 (e.g., a second shield) that covers at least a portion of the inner shield 2284 (e.g., the first inner shield 2286, the second inner shield 2288, and the spacer 2290). For example, the outer shield 2292 may cover an outer circumferential surface and an outer end of the inner shield 2284. In the illustrated embodiment, the outer shield 2292 includes a first outer shield 2294 and a second outer shield 2296. The first outer shield 2294 may be integrated with the housing 2228 or may be attached to the housing 2228 in any number of ways, including, for example, with one or more fasteners (e.g., one or more bolts passing through one or more holes through the first outer shield 2294 and one or more threaded holes such as in the housing 2228). The torque sensor 2202 may thus be attached to the housing 2228 via the attachment of the first outer shield 2294 to, for example, the housing 2228. The first outer shield 2294 may cover a first portion of the inner shield 2284, including, for example, an outer circumferential surface and an outer end of the first inner shield 2286, and a first portion of an outer circumferential surface of the spacer 2290. The second outer shield 2296 may cover a second portion of the inner shield 2284, including, for example, an outer circumferential surface and an outer end of the second inner shield 2288, and a second portion of an outer circumferential surface of the spacer 2290. The second outer shield 2296 may be attached to the first outer shield 2294 to form the outer shield 2292. For example, the second outer shield 2296 may be attached to the first outer shield 2294 with one or more fasteners (e.g., one or more bolts passing through one or more holes through the first outer shield 2294 and one or more holes through the second outer shield 2296), an adhesive, a weld, and / or another attachment configuration. The first outer shield 2294 and the second outer shield 2296 each include flanges 2298, and the first outer shield 2294 and the second outer shield 2296 may be attached to each other via these flanges. The first outer shield 2294 and the second outer shield 2296 may be attached to each other via holes 2299 (see FIG. 26) passing through the first outer shield 2294 and the second outer shield 2296, respectively, with bolts that may extend through the flanges 2298, respectively. The outer shield 2292 (e.g., the first outer shield 2294 and the second outer shield 2296) may be made of any number of materials (e.g., a second shield material). For example, the first outer shield 2294 and the second outer shield 2296 may be made of the same material, such as, for example, a non-ferromagnetic (e.g., permeability 1), electrically conductive material. Such a non-ferromagnetic, electrically conductive material may be, for example, aluminum 7075, but other materials may also be used. In one embodiment, different non-ferromagnetic, electrically conductive materials are used for the first outer shield 2296 and the second outer shield 2298, respectively. In the case where the outer shield 2294 is included within the torque sensor 2202, when the torque sensor 2202 undergoes a small axial movement within the dynamic system of the drive unit 2204, the impedance seen by the coils of the torque sensor 2202 (e.g., the first excitation coil 2268, the second excitation coil 2282, the first sensing coil 2270, and the second sensing coil 2280) does not change; thus, the change in the amplitude of the measured signal can be minimized. This increases the reliability of the torque sensor 2202 and almost completely encompasses the magnetic field of the torque sensor 2202. Additionally, this increases the symmetry of the first sensing coil 2270 and the second sensing coil 2280, which helps to minimize measurement errors. The components of the torque sensor 2202 (e.g., the support 2250, the first excitation coil 2268, the first sensing coil 2270, the second sensing coil 2280, the second excitation coil 2282, and the inner shield 2284) can be held within the torque sensor 2202 via a friction fit provided by the attachment of the second outer shield 2296 to the first outer shield 2294. For example, the bolts used to attach the second outer shield 2296 to the first outer shield 2294 can be tightened, and the components of the torque sensor 2202 can be housed within the outer shield 2292 to apply axial pressure to the components of the torque sensor 2202 and prevent axial and / or radial movement of the components of the torque sensor 2202. The components of the torque sensor 2202 can thus be connected and positioned stably relative to the housing 2228. The components of the torque sensor 2202 can be attached to the outer shield 2294 and / or the housing 2228 of the torque sensor 2202 in any number of other ways, including, for example, using an adhesive. In one embodiment, the outer shield 2294 is a single component that covers at least portions of both the first inner shield 2286 and the second inner shield 2288 as well as the spacer 2290. This single-component outer shield 2294 can be integrated with the housing 2228 or can be attached to the housing 2228 in any number of ways, including, for example, using one or more fasteners into one or more openings (e.g., threaded openings) in the housing 2228, respectively. The components of the torque sensor 2202 and the outer housing 2294 of the torque sensor 2202 can be of any number of shapes and / or sizes. Referring to FIG. 26, for example, the components of the torque sensor 2202 (e.g., the support 2250, including the first support 2252 and the second support 2254; the first excitation coil 2268; the first sensing coil 2270; the second sensing coil 2280; the second excitation coil 2282; the inner housing 2284, including the first inner housing 2286 and the second inner housing 2288; and the spacer 2290) and the outer housing 2294 of the torque sensor 2202 that houses the components of the torque sensor 2202 can be annular in shape. The inner diameter of one of the supports 2250 can be sized such that the torque sensor 2202 can be positioned to surround the output ring 2224 of the clutch mechanism 2222, with a radial gap 2230 therebetween, for example, between the support 2250 and the output ring 2224 of the clutch mechanism 2222. By constructing two similar or identical magnetic circuits, a first magnetic circuit 2256 on the HSZ and a second magnetic circuit 2258 on the LSZ, a strain difference between the HSZ and the LSZ can be isolated. A voltage applied to the first excitation coil 2268 and the second excitation coil 2282 induces signals (e.g., voltages) in the first sensing coil 2270 and the second sensing coil 2280, respectively. A processor of the torque sensor 2202 or the bicycle can, for example, receive signals (e.g., signals from ADC conversion) from the first sensing coil 2270 and the second sensing coil 2280 and determine a difference (e.g., a differential signal; differential voltage) between the measured signals. The differential voltage varies with torque, but sensor deviation or drift caused by thermal expansion of the components of the clutch mechanism 2222 and / or the torque sensor 2202 can be eliminated. The processor can determine a reaction torque based on the differential voltage. For example, the reaction torque can be determined based on a predetermined function (e.g., experimentally determined), using the differential voltage as an input. The torque sensor 2202 may include more, fewer, and / or different components. For example, the torque sensor 2202 may include a third shield that at least partially covers the second shield 2294. The third shield may, for example, shield external, low-frequency magnetic fields. If the external magnetic field is not properly shielded, the external magnetic field may leak into the torque sensor 2202 and cause measurement errors. The external magnetic field may saturate the internal ferromagnetic return path or may create a permeability gradient between two chambers, as the permeability depends on the magnetic field strength. The third shield may be made of any number of different materials, including, for example, a ferromagnetic ceramic material (e.g., a ferrite), such that the third shield gives the external magnetic field a low magnetic resistance return path back to the source. The first shield 2284 may contain a high-frequency magnetic field within the torque sensor 2202, the second shield 2294 may shield the torque sensor 2202 from high-frequency external magnetic fields, and the third shield may shield the torque sensor 2202 from low-frequency external magnetic fields. This may increase the reliability and usability of the torque sensor 2202. The torque sensor 2202 may be mounted to other rotational stabilizing components of the drive unit 2204 (e.g., rather than the housing 2228). For example, referring to FIG. 31, the drive unit 2204 may include end caps 2300, 2302 on opposite ends 2304, 2306 of the housing 2228, respectively. The end caps 2300, 2302 may be attached to the housing 2228 of the drive unit 2204 at the opposite ends 2304, 2306 thereof in any number of ways, including, for example, via threaded connection structures. Other configurations may be provided. As shown in the example of FIG. 31, the torque sensor 2202 may be attached to the end cap 2302 of the drive unit 2204 (e.g., via the second outer shield 2296) such that the torque sensor 2202 and the output ring 2224 of the clutch mechanism 2222 are separated by a radial gap 2230. The torque sensor 2202 may be attached to the end cap 2302 of the drive unit 2204 in any number of ways, including, for example, using one or more fasteners. FIG. 32 illustrates a bicycle control system 3200 that includes a plurality of manual control devices 142A-D; a system control device 150; at least one sensor 3202, such as a sensor 141 (e.g., a torque sensor), a cadence sensor, and / or a speed sensor 3206; and bicycle components 3208A-B, such as a rear derailleur and / or a front derailleur, or one or more internal gear hubs. The manual control devices 142A-D are communicatively coupled to the system control device 150, such as by a cable or wirelessly, to transmit control signals to the system control device 142. The system control device 150 is configured to transmit control signals to the components 3208A-B in response to the received control device signals or the result from the automatic shifting determination. In one embodiment, the system control device 150 is configured to transmit control signals wirelessly to one or more bicycle components 3208A-B. The control signals can be wirelessly communicated using any technology, protocol, or standard. For example, the Institute of Electrical and Electronics Engineers (「IEEE」) 802.11 standard, the IEEE 802.15.1 or BLUETOOTH® standard, the ANT™ or ANT+™ standard, and / or the AIREA™ standard can be used. The bicycle components 3208A-B can be any bicycle components. For example, the components 3208A-B can be a drive chain component and / or a suspension component. In one embodiment, one component 3208A can be a rear derailleur and another component 3208B can be a front derailleur. Other components can also be included. For example, the system control device 150 can communicate with three or more components, such as a front derailleur, a rear derailleur, and a front suspension system, or provide control signals to the three or more components. Alternatively, the system control device 150 can provide control signals to only a single component 3208A. In one embodiment, a receiver can wirelessly transmit control signals to a component 3208A, and the component 3208A can transmit the control signals to another component 3208B. In one embodiment, the bicycle control system 3200 includes at least one manual control device 142 that includes a control mechanism for generating a control signal to control at least one bicycle component 3208A. The system control device 150 can be a stand-alone device or can be integrated with one or more components 3208A-B. FIG. 33 is a block diagram of an exemplary control system 3300 for a bicycle, which can be used to implement a system control device 150. The control system 3300 can be used alone to communicate with and control bicycle components, or the control system 3300 can be used in combination with at least one other control system for components of the bicycle, such as a main control system, which can include alternative control devices, such as a brake lever housing integrating a shift controller. The control system 3300 includes a system control device 150, one or more control devices 142, and / or one or more sensors 141. The system control device 150 includes a processor 3302, a memory 3304, a sensor communication interface 3306, a power supply 3308, and a control device interface 3310. Optionally, the system control device 150 may also include a user interface 3312. In addition, additional, different, or fewer components are possible for the system control device 150. The processor 3302 can include a general-purpose processor, a digital signal processor, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), analog circuitry, digital circuitry, combinations thereof, or other processors now known or later developed. The processor 3302 can be a single device or a combination of devices such as through shared or parallel processing. In one embodiment, for example, a CPU 3302 used can be an Atmel® ATmega324PA microprocessor having an internal eeprom memory, and a transmitter and a receiver used can be an Atmel® AT86RF231 2.4GHz transceiver that utilizes AES encryption and DSS spread spectrum technology and supports 16 channels and the IEEE 802.15.4 communication protocol. The memory 3304 can be an electrical memory or a non-electrical memory. The memory 3304 can include one or more of the following: a read-only memory (ROM), a random access memory (RAM), a flash memory, an electrically erasable programmable read-only memory (EEPROM), or other types of memory. The memory 3304 can be removable from the system control device 150, such as a secure digital (SD) memory card. In a particular non-limiting exemplary embodiment, a computer-readable medium can include a solid-state memory, such as a memory card or other package housing one or more non-electrical read-only memories. Additionally, the computer-readable medium can be a random access memory or other electrically rewritable memory. Additionally, the computer-readable medium can include a magneto-optical or optical medium, such as a disk or tape or other storage device. Accordingly, the present disclosure is considered to include any one or more of a computer-readable medium and other equivalents and successor media in which data or instructions can be stored. The memory 3304 is a non-transitory computer-readable medium and is described as a single medium. However, the term "computer-readable medium" includes a single medium or multiple media, such as a centralized or distributed memory structure, and / or an associated cache memory operable to store one or more instruction sets and other data. The term "computer-readable medium" should also include any medium that is capable of storing, encoding, or carrying an instruction set for execution by a processor, or any medium that causes a computer system to perform any one or more of the methods or operations disclosed herein. In an alternative embodiment, dedicated hardware implementations such as application specific integrated circuits, programmable logic arrays, and other hardware devices can be constructed to perform one or more of the methods described herein. Applications of devices and systems that may include various embodiments can broadly include a variety of electronic and computer systems. One or more of the embodiments described herein can be implemented using two or more specific interconnected hardware modules or devices with associated control, and data signals that can communicate between and through the modules, or as part of an application specific integrated circuit. Accordingly, the system encompasses software, firmware, and hardware implementations. The power supply 3308 is a portable power supply that can be stored inside or outside the system control device 150 and communicates with the system control device 150 through an electrical conduction cable. The power supply 3308 can be involved in the generation of electricity, such as using a mechanical generator, a fuel cell device, photovoltaic cells, or other power generation devices. The power supply 3308 can include a battery pack, such as a device composed of two or more electrochemical cells that convert stored chemical energy into electrical energy. The power supply 3308 can include a combination of multiple battery packs or other power supply devices. Battery pack types that can be specially adapted or assembled can be used, or standard battery pack types such as CR 2012, CR 2016, and / or CR 2032. The control device interface 3310 provides data transfer from the control device 142 to the system control device 150. The control device interface 3310 includes wired conduction signals and / or data communication circuitry operable to interpret signals provided by different control devices 142. For example, the control device interface 3310 can include a series of ports for receiving control device input cables. Each of these ports can be distinguished by the processor 3302, either by grouping tables or arrays, or by providing physical circuitry or other circuitry for grouping control device inputs. Alternatively, different control devices 142 can communicate wirelessly with the system control device 150, as described herein. The user interface 3312 can be one or more buttons, a keypad, a keyboard, a mouse, a stylus, a trackball, a rocker switch, a touchpad, a voice recognition circuit, or other devices or components for communicating data between a user and the system control device 150. The user interface 3312 can be a touch screen, which can be capacitive or resistive. The user interface 3312 can include a liquid crystal display (「LCD」) panel, light emitting diodes (LEDs), an LED screen, a thin film transistor screen, or another type of display. The user interface 3312 can also include audio capabilities or speakers. In one embodiment, the user interface is configured to provide a user with a notification that the system control device 150 has entered the automatic mode, has paused the automatic mode, has exited the automatic mode, and / or has modified a parameter of the automatic mode. The notification can be auditory, visual, and / or tactile. For example, an audible beep can be used. In one embodiment, an LCD panel is configured to display a visual notification. In one embodiment, the user interface 3312 includes a plurality of buttons and an LED indicator. The plurality of buttons are used to convey commands to the system control device 150, and the LED indicator emits light to indicate the input of the commands. The sensor communication interface 3306 is configured to transfer data such as sensor values with at least one sensor 141. The sensor communication interface 3306 uses any operable connection to transfer data. An operable connection can be a connection in which signals, physical communication content, and / or logical communication content can be sent and / or received. An operable connection can include a physical interface, an electrical interface, and / or a data interface. The sensor communication interface 3306 provides wireless communication in any currently known or later developed format. This document describes wireless communication between components. Although this specification describes components and functions that can be implemented in specific wireless communication embodiments with reference to specific standards and protocols, the present invention is not limited to these standards and protocols. For example, the standards for Internet and other packet-switching network transmissions (e.g., TCP / IP, UDP / IP, HTML, HTTP, HTTPS) are examples of the current state of the art. These standards are periodically replaced by faster or more efficient equivalents with essentially the same functions. Accordingly, replacement standards and protocols with the same or similar functions as those disclosed herein are considered to be their equivalents. In one embodiment, the components of the bicycle described herein will communicate with each other. In the case of wireless communication, these components will initially be paired to allow for secure communication between the components on the bicycle, without interference from devices of non-associated systems. Subsequently, one or more of these components may be paired with a separate device such as a computer, tablet, or mobile phone. This paired device can provide an interface to the user to allow the user to communicate with the components on the bicycle such as the system control device 150. Examples of communication are for updating firmware, setting variables, and running diagnostic tools and analysis. According to various embodiments of the present disclosure, the methods described herein can be implemented by software programs executable by a computer system such as the system control device 150. Additionally, in an exemplary non-limiting embodiment, the implementation can include distributed processing, component / object distributed processing, and parallel processing. Alternatively, virtual computer system processing can be constructed to implement one or more of the methods or functionality described herein. The methods and techniques described herein can be implemented using the hardware configurations described herein and one or more computer programs that provide instructions for the hardware. A computer program (also known as a program, software, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, and can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable in an operating environment. A computer program does not necessarily correspond to a file in a file system. A program can be stored in a part of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program, or in multiple coordinated files (e.g., files that store one or more modules, subroutines, or portions of code). A computer program can be deployed to execute on one computer or on multiple computers located at one site or distributed across multiple sites and interconnected by a communication network. The processing procedures and logic flows described in this specification can be performed by one or more programmable processors executing one or more computer programs to perform functions by operating on input data and generating output. These processing procedures and logic flows can also be performed by, and the apparatus can also be implemented as, special purpose logic circuitry (e.g., a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC)). As used in this application, the term "circuit system" or "circuit" means all of the following: (a) only hardware circuit implementations (such as implementations in only analog and / or digital circuit systems); and (b) combinations of circuits and software (and / or firmware), such as (where applicable): (i) a combination of processors, or (ii) portions of a processor / software (including a digital signal processor, software, and memory, which operate together to cause a device such as a mobile phone or a server to perform various functions); and (c) a circuit, such as a microprocessor or a portion of a microprocessor, that requires software or firmware to operate, even if the software or firmware is not physically present. This definition of "circuit system" applies to all uses of this term in any claim in this application. As a further example, as used in this application, the term "circuit system" will also encompass an implementation having only one processor (or multiple processors) or a portion of a processor and its (or their) accompanying software and / or firmware. The term "circuit system", for example and if applicable to a particular claim element, will also encompass: a baseband integrated circuit or an application processor integrated circuit for a mobile computing device, or a similar integrated circuit in a server, a cellular network device, or other network device. Processors suitable for the execution of a computer program include, for example, both general and special purpose microprocessors, as well as any one or more processors of any kind of digital computer. Generally speaking, a processor receives instructions and data from a read-only memory, or a random access memory, or both. The basic elements of a computer are a processor for executing instructions, and one or more memory devices for storing the instructions and data. Generally speaking, a computer also includes one or more mass storage devices for storing data, or operatively coupled to receive or transmit data from or to them, or both, the one or more mass storage devices being, for example, magnetic disk drives, magneto-optical disks, or optical disks. However, a computer need not have such devices. Furthermore, a computer may be embedded in another device, such other device being, for example, a mobile phone, a personal digital assistant ("PDA"), a mobile audio player, a global positioning system ("GPS") receiver, or a system control device 150, to name just a few examples. Computer-readable media suitable for storing computer program instructions and data include all forms of non-volatile memory, media, and memory devices, for example, including semiconductor memory devices such as EPROM, EEPROM, and flash memory devices; magnetic disks such as internal hard disks or removable magnetic disks; magneto-optical disks; and CD ROM and DVD-ROM disks. The processor and memory may be supplemented by, or incorporated in, special purpose logic circuitry. In one embodiment, a system control device 150 is integrated with a mobile phone, PDA, a mobile audio player, a GPS receiver, and wirelessly communicates with bicycle components to provide automatic mode control. As can be recognized from the foregoing discussion, the present invention can be embodied in various forms including but not limited to the following examples: Example 1: A torque sensor for a bicycle, the torque sensor comprising: a support member that can be disposed around a device of the bicycle such that the support member and the device of the bicycle are separated by an air gap; an excitation coil supported by the support member; and a sensing coil supported by the support member at a distance from the excitation coil in an axial direction of the support member, wherein the excitation coil is configured to induce a voltage in the sensing coil via the device of the bicycle when the support member is disposed around the device of the bicycle, and the induced voltage is related to a torque in the device. Example 2: The torque sensor as in Example 1, further comprising a shield covering the excitation coil and the sensing coil. Example 3: The torque sensor as in Example 2, further comprising a second sensing coil, and the shield also covers the second sensing coil. Example 4: The torque sensor as in Example 1, wherein the bicycle is an electric bicycle and the device of the bicycle is a clutch mechanism of the electric bicycle, and wherein the support member is a hollow cylinder that can be disposed around a part of the clutch mechanism of the electric bicycle. Example 5: The torque sensor as in Example 1, wherein the support member includes a first groove and a second groove that extend around an outer periphery of the support member, the second groove is offset relative to the first groove along the axial direction of the support member, and wherein the excitation coil is disposed in the first groove and the sensing coil is disposed in the second groove. Example 6: The torque sensor as in Example 5, wherein the sensing coil is a first sensing coil and the axial direction is a first axial direction, wherein the support member further includes a third groove that extends around the outer periphery of the support member, the third groove is offset relative to the first groove along a second axial direction of the support member, the second axial direction is opposite to the first axial direction of the support member, and wherein the torque sensor further comprises a second sensing coil that is disposed around and supported by the support member, and the second sensing coil is disposed in the third groove. Example 7: The torque sensor as in Example 6, wherein the excitation coil is a first excitation coil, wherein the support member further includes a fourth groove that extends around the outer periphery of the support member, the fourth groove is offset relative to the first groove along the first axial direction or the second axial direction, and wherein the torque sensor further comprises a second excitation coil that is disposed around and supported by the support member, and the second excitation coil is disposed in the fourth groove.Example 8: A torque sensor as in Example 7, wherein the first excitation coil and the first sensing coil form a first magnetic circuit, and the second excitation coil and the second sensing coil form a second magnetic circuit, wherein the support has a first portion that houses a first part of the first magnetic circuit and a second portion that houses a second part of the second magnetic circuit, wherein the torque sensor further includes a shield that separates the first portion of the support from the second portion of the support such that the first magnetic circuit is separated from the second magnetic circuit, and wherein the shield covers at least a portion of the support. Example 9: A torque sensor as in Example 8, wherein the shield covers at least the first groove, the second groove, the third groove, and the fourth groove, and wherein the shield is made of a ferrite. Example 10: A torque sensor as in Example 9, wherein the shield is a first shield, wherein the torque sensor further includes a second shield that at least partially covers the first shield, and wherein the second shield is made of a non-ferromagnetic, conductive material. Example 11: A torque sensor as in Example 1, wherein the support is formed by a plurality of stacked printed circuit boards (PCBs), and wherein the excitation coil is formed on, in, or on and in a first printed circuit board (PCB) of the plurality of stacked PCBs, and the sensing coil is formed on, in, or on and in a second PCB of the plurality of stacked PCBs. Example 12: A clutch mechanism for an electric bicycle, the clutch mechanism including: an inner race; an outer race rotatably positioned around the inner race; and a torque sensor positioned around one of the inner race and the outer race such that the torque sensor and the race are separated by an air gap, the torque sensor configured to measure a torque within the clutch mechanism and including: a housing that can be disposed around the race; an excitation coil disposed around the housing and supported by the housing; a first sensing coil disposed around the housing and supported by the housing at a first distance away from the excitation coil in a first axial direction of the housing; and a second sensing coil disposed around the housing and supported by the housing at a second distance away from the excitation coil in a second axial direction of the housing, the second axial direction of the housing being opposite to the first axial direction of the housing, wherein the excitation coil is configured to induce a voltage in the first sensing coil via the race, the induced voltage being related to a torque within the clutch mechanism. Example 13: A clutch mechanism as in Example 12, wherein the race is the outer race, and the outer race is a shaft of a link of the electric bicycle. Example 14: A clutch mechanism as in Example 12, wherein the excitation coil is a first excitation coil, wherein the torque sensor further includes: a second excitation coil disposed around the housing and supported by the housing, the second excitation coil being offset relative to the first excitation coil in the second axial direction.Example 15: A clutch mechanism as in Example 14, wherein the housing includes a first groove, a second groove, a third groove, and a fourth groove, which extend around an outer periphery of the housing, and the first groove, the second groove, the third groove, and the fourth groove are offset from each other along the first axial direction of the housing, and wherein the first excitation coil is disposed in the first groove, the first sensing coil is disposed in the second groove, the second sensing coil is disposed in the third groove, and the second excitation coil is disposed in the fourth groove. Example 16: A clutch mechanism as in Example 15, wherein the torque sensor further includes a shield that separates the first excitation coil and the first sensing coil from the second sensing coil and the second excitation coil, and covers the first groove, the second groove, the third groove, and the fourth groove. Example 17: A clutch mechanism as in Example 16, wherein the shield is a first shield and is made of a first material, and wherein the torque sensor further includes a second shield that partially covers the first shield and is made of a second material different from the first material. Example 18: A clutch mechanism as in Example 17, wherein the voltage is a first voltage, wherein the second excitation coil is configured to induce a second voltage in the second sensing coil via the seat ring, and wherein the clutch mechanism further includes a processor that is configured to determine the torque in the clutch mechanism based on the induced first voltage and the induced second voltage. Example 19: A clutch mechanism as in Example 18, wherein the processor is further configured to determine a difference between the induced first voltage and the induced second voltage, and wherein the processor is configured to determine the torque in the clutch mechanism based on the induced first voltage and the induced second voltage, including the processor being configured to determine the torque in the clutch mechanism based on the determined difference between the induced first voltage and the induced second voltage. Example 20: A torque sensor for a bicycle, the torque sensor comprising: a support member that can be disposed adjacent to a seat ring of a clutch, a coil supported by the support member, the coil being disposed around an entire periphery of the seat ring, the coil being configured to sense a current regarding a torque in the seat ring. The illustrations of the embodiments described herein are intended to provide a general understanding of the structures of the various embodiments. These illustrations are not intended to serve as a complete description of all elements and features of the devices and systems that utilize the structures or methods described herein. After reviewing this disclosure, many other embodiments will be apparent to those of ordinary skill in the art. Other embodiments can be utilized and derived from this disclosure, such that structural and logical substitutions and changes can be made without departing from the scope of this disclosure. Additionally, these illustrations are only representative and may not be drawn to scale. Some of the scales in these illustrations may be enlarged and others minimized. Accordingly, this disclosure and the figures are to be regarded as illustrative rather than restrictive. Although this specification contains many details, these should not be construed as limitations on the scope or claims of the invention, but rather as descriptions of features specific to particular embodiments of the invention. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, the various features described in the context of a single embodiment can also be implemented separately or in any suitable sub-combination in multiple embodiments. Additionally, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be deleted from the combination, and the claimed combination can be directed to a sub-combination or variation of a sub-combination. Similarly, although operations and / or acts are illustrated in the figures and described herein in a particular order, this should not be understood as requiring that these operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed to achieve the desired result. In some cases, multitasking and parallel processing may be advantageous. Moreover, the separation of the various system components in the embodiments described above should not be understood as requiring such separation in all embodiments, and it should be understood that any of the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products. In this document, one or more embodiments of this disclosure can be referred to individually and / or collectively by the term "invention" for convenience only and is not intended to voluntarily limit the scope of this application to any particular invention or inventive concept. Moreover, although specific embodiments have been illustrated and described herein, it should be understood that any subsequent arrangement designed to achieve the same or similar purpose can replace the specific embodiments shown. This disclosure is intended to cover any and all subsequent adaptations or variations of the various embodiments. After reviewing this description, combinations of the above embodiments and other embodiments not specifically described herein will be apparent to those of ordinary skill in the art. The abstract of the present disclosure is provided to comply with 37 C.F.R. § 1.72(b), and is accompanied by the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Additionally, in the foregoing embodiments, for the purpose of streamlining the present disclosure, various features may be grouped together or described in a single embodiment. This disclosure should not be construed as reflecting an intention that the claimed embodiments require more features than those expressly recited in each claim. Rather, as the following claims reflect, the subject matter of the invention may lie in less than all of the features of any of the disclosed embodiments. Accordingly, the following claims are incorporated into the embodiments, where each claim stands on its own as a separate definition of the claimed subject matter. It is intended that the foregoing detailed description be regarded as illustrative rather than limiting, and it should be understood that the following claims, including all equivalents thereof, are intended to define the scope of the invention. The claims should not be construed as limited to the order or elements recited, unless stated to that effect. Accordingly, all embodiments falling within the scope and spirit of the following claims and their equivalents are claimed as the invention. 100: Bicycle 102: Frame 104: Handlebar 106: Saddle 108: Front wheel 110: Front fork 112: Rear wheel 114: Rear suspension assembly 116: Drive chain 118,2214: Crank assembly 120: Chain 122: Electric rear derailleur, rear derailleur 123,2218: Crank 124: Rear sprocket 125: Pedal 126: Controller 128: Electric bicycle control system 130: Battery pack, power source 137: Down tube 138,2204: Drive unit 140: Crankshaft 141,3202: Sensor 142: Control device 142A-D: Manual control device 143: Link 146: Electric drive motor, auxiliary motor 150: System control device, system controller 152: Control unit 200: Base member 201: Linkage group 202: Outer link 204: Inner link 206: Movable member 208: Chain guide assembly 210: Cage plate 212: Proximal end 214: Motor module 216: Battery pack 218: Distal end 220: Tensioner wheel, wheel 222: Tooth 224: Guide wheel 300,2224: Output ring 302: Overrunning clutch mechanism of the type with a stop washer, clutch mechanism 303: Shield 304: Stop washer element, element 306,306A,1700,2202: Torque sensor 307: Outer shield, inner shield 308: Support member 310: Excitation coil 312: Sensing coil 312a: First sensing coil, sensing coil 312b: Second sensing coil, sensing coil 314: Groove 314a: First groove, groove 314b,2262: Second groove 314c: Third groove, groove 700: Excitation coil driver circuit 702: Oscillator circuit 704: Power amplifier, gate driver 706: H-bridge circuit 708: Crystal 710: Inverting amplifier 712,806a,806b: Capacitor 714: Resistor 716: Power MOSFET 800a: First signal conditioning circuit, signal conditioning circuit 800b: Second signal conditioning circuit, signal conditioning circuit 802a: First clamping circuit, clamping circuit 802b: Second clamping circuit, clamping circuit 804a: First peak-to-peak detector circuit, peak-to-peak detector circuit 804b: Second peak-to-peak detector circuit, peak-to-peak detector circuit 900: Signal conditioning circuit 902: Clamping circuit 904: Peak-to-peak detector circuit 1702: Excitation coil, coil 1704: Sensing coil, coil 1706: PCB 1708: Layer 1708a: First layer, layer 1708b: Second layer, layer 1708c: Third layer, layer 1708d: Fourth layer, layer 1708e: Fifth layer, layer 1708f: Sixth layer,Layer 1710: Substrate 1712: Trace 1713: Input terminal 1714, 1716: First through-hole 1718, 1720: Second through-hole 1722, 1724: Third through-hole 1726, 1728: Fourth through-hole 1730, 1732: Fifth through-hole 1734: Output terminal 2200: Drive system 2206: Support structure 2206a, 2252: First support 2206b, 2254: Second support 2208: Recessed portion 2210, 2210a: Opening 2212: Attachment feature 2216: Crankshaft, crank 2222: Clutch mechanism 2224: Outer ring 2226: Overrunning clutch mechanism, one-way clutch mechanism 2228: Housing 2230: Radial clearance 2232: Rotor 2234: Stator 2236: Reducer 2238: Link shaft 2240, 2242: Bushing 2244: Bearing 2250: Support 2256: First magnetic circuit 2258: Second magnetic circuit 2260: First groove 2264, 2276: Outer side 2266: First axial direction 2268: First excitation coil 2270: First sensing coil 2272: Third groove 2274: Fourth groove 2278: Second axial direction 2280: Second sensing coil 2282: Second excitation coil 2284: Inner shield, first shield 2286: First inner shield 2288: Second inner shield 2290: Spacer 2292: Outer shield 2294: First outer shield, outer shield, second shield 2296: Second outer shield 2298: Flange 2299: Hole 2300, 2302: End cap 2304, 2306: End 3200: Bicycle control system 3208A - B: Bicycle component, component 3206: Speed sensor 3300: Control system 3302: Processor, CPU 3304: Memory 3306: Sensor communication interface 3308: Power supply 3310: Control device interface 3312: User interface A: Arrow D1: First rotation direction D2: Second rotation direction, After reading the following description in conjunction with the drawings, the objects, features, and advantages of the present invention will become apparent, wherein: FIG. 1 is a side view of an example of an electric bicycle including a torque sensor according to the teachings of the present disclosure; FIG. 2 is a side view of an example of a rear derailleur; FIG. 3 is a perspective view of a first embodiment of a torque sensor for a bicycle; FIG. 4 is a first cross-section of the torque sensor of FIG. 3; FIG. 4B is a cross-section of a torque sensor similar to the torque sensor of FIG. 3 and including a shield; FIG. 5 is a close-up of a cross-section of FIG. 4; FIG. 6 is a second cross-section of the torque sensor of FIG. 3; FIG. 7 is a circuit diagram of an embodiment of an excitation coil driver for a torque sensor; FIG. 8 is a circuit diagram of a first example of sensor signal conditioning; FIG. 9 is a circuit diagram of a second example of sensor signal conditioning; FIG. 10 is an example of a graph of input torque versus time; FIG. 11 is an example of a graph of sensed voltage versus time for a first sensing coil of a torque sensor corresponding to the input torque shown in FIG. 10; FIG. 12 is an example of a graph of sensed voltage versus time for a second sensing coil of a torque sensor corresponding to the input torque shown in FIG. 10; FIG. 13 is an example of a graph of excitation voltage versus time in an excitation coil of a torque sensor; FIG. 14 is an example of a graph of sensed voltage versus time for a sensing coil of a torque sensor corresponding to the excitation voltage shown in FIG. 13; FIG. 15 is an example of sensed voltage versus time corresponding to the excitation voltage shown in FIG. 13 after clamping; FIG. 16 is an example of sensed voltage versus time corresponding to the excitation voltage shown in FIG. 13 after clamping and peak detection; FIG. 17 is a perspective view of a second embodiment of a torque sensor for a bicycle; FIG. 18 is a first cross-section of the torque sensor of FIG. 17; FIG. 19 is a close-up of the cross-section of FIG. 18; FIG. 20 is a second cross-section of the torque sensor of FIG. 17; FIG. 21 is an exploded view of a coil of the torque sensor of FIG. 18; FIG. 22 is a front view of a first embodiment of a drive system of a bicycle including a third embodiment of a torque sensor; FIG. 23 is a perspective view of the drive system of FIG. 22; FIG. 24 is a top view of the drive system of FIG. 22; FIG. 25 is a cross-section of the drive system of FIG. 22; FIG. 26 is an exploded view of a third embodiment of a torque sensor; FIG. 27 is a close-up of a part of an embodiment of a drive unit of the drive system of FIG. 22; FIG. 28 is a cross-section of the part of the drive unit of FIG. 27 showing the third embodiment of the torque sensor; FIG. 29 is a first特写 of a cross-section of a portion of the drive unit of FIG. 28 showing a third embodiment of the torque sensor; FIG. 30 is a second特写 of a cross-section of a portion of the drive unit of FIG. 28 showing a third embodiment of the torque sensor; FIG. 31 is a cross-section of a second embodiment of a drive system of a bicycle, which includes a third embodiment of a torque sensor; FIG. 32 is a block diagram of an exemplary bicycle control system for implementing a method of controlling a bicycle; and FIG. 33 is a block diagram of an exemplary control device for implementing a method of controlling a bicycle. Other aspects and advantages of the embodiments disclosed herein will become apparent after considering the following detailed description, where like or identical structures have like reference numerals. 140: crankshaft 300: output ring 302: ratchet pad type rotary clutch mechanism, clutch mechanism 306: torque sensor 308: support 310: excitation coil 312a: first sensing coil, sensing coil 312b: second sensing coil, sensing coil It should be noted that the term "特写" in the original text seems not to be a standard English term. Here it is tentatively translated as "特写", but it may need to be adjusted according to the specific context.

Claims

1. A torque sensor for a bicycle, the torque sensor comprising: a support member disposed near a seat ring of a clutch; a sensing coil supported by the support member, the sensing coil being configured to surround the entire seat ring, the sensing coil being configured to sense a current related to strain in a ring clamp of the seat ring.

2. The torque sensor of claim 1, further comprising an excitation coil supported by the support member at a distance from the sensing coil in an axial direction of one of the support members, wherein, The excitation coil system is configured to induce the current in the sensing coil via the clutch race.

3. The torque sensor of claim 2 further includes a cover covering the excitation coil and the sensing coil.

4. The torque sensor of claim 3 further includes a second sensing coil, and the shield also covers the second sensing coil.

5. The torque sensor as described in claim 2, wherein, The support includes a first groove and a second groove extending around one of the outer sides of the support. The second groove is offset from the first groove in the axial direction of the support. The excitation coil is disposed in the first groove, and the sensing coil is disposed in the second groove.

6. The torque sensor as described in request item 5, wherein, The sensing coil is a first sensing coil, and the axial direction is a first axial direction. The support further includes a third groove that extends around the outer side of the support. The third groove is offset from the first groove in a second axial direction of the support, which is opposite to the first axial direction of the support. The torque sensor further includes a second sensing coil that is arranged to surround the support and is supported by the support. The second sensing coil is disposed in the third groove.

7. The torque sensor as described in claim 6, wherein, The excitation coil is a first excitation coil, wherein the support further includes a fourth groove extending around the outer side of the support, the fourth groove being offset from the first groove in the first axial direction or the second axial direction, and wherein the torque sensor further includes a second excitation coil arranged to surround and be supported by the support, the second excitation coil being disposed within the fourth groove.

8. The torque sensor as described in request item 7, wherein, The first excitation coil and the first sensing coil form a first magnetic circuit, and the second excitation coil and the second sensing coil form a second magnetic circuit. The support member has a first portion for receiving the first magnetic circuit and a second portion for receiving the second magnetic circuit. The torque sensor further includes a shield that separates the first portion of the support member from the second portion of the support member, thereby separating the first magnetic circuit from the second magnetic circuit. The shield covers at least a portion of the support member.

9. The torque sensor as described in request item 8, wherein, The shield covers at least the first groove, the second groove, the third groove and the fourth groove, and wherein the shield is made of ferrite.

10. The torque sensor as described in claim 9, wherein, The shield is a first shield, wherein the torque sensor further includes a second shield that at least partially covers the first shield, and wherein the second shield is made of a non-ferromagnetic conductive material.

11. The torque sensor as described in claim 2, wherein, The support is formed of multiple stacked printed circuit boards (PCBs), wherein the excitation coil is formed on, or in, one of the multiple stacked PCBs on a first PCB, or on and in the first PCB, and the sensing coil is formed on, or in, one of the multiple stacked PCBs on a second PCB, or on and in the second PCB.

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