Power meter for measuring power transmitted by a translating chain

Abstract

A power meter includes a chain channel, a sensing bracket, a strain gauge, and a chain speed sensor. The chain channel includes a chain inlet, a convex deviation, and a chain outlet, and includes a pair of vertically opposing ridges extending along the channel path, each ridge is characterized by a ridge width less than an inner width of a chain of the vehicle. The channel is characterized by a channel height between the pair of vertically opposing ridges greater than or equal to a roller diameter of the chain. The sensing bracket spans the pair of vertically opposing ridges and is configured to measurably deflect in response to a force applied by the chain to the ridges. The strain gauge is configured to measure deflection of the sensing bracket. The chain speed sensor is configured to measure a speed of the chain translating through the chain channel.

Description

BKON-M01-PCTPOWER METER FOR MEASURING POWER TRANSMITTED BY A TRANSLATING CHAINCROSS REFERENCE TO RELATED APPLICATIONS

[0001] This Application claims the benefit of U.S. Provisional Application No. 63 / 752,592, filed on 31 -JAN-2025, which is incorporated in its entirety by this reference.TECHNICAL FIELD

[0002] This invention relates generally to the field of tensiometer, power meter, and bicycle power meter design and, more specifically, to a new and useful system for measuring the tension of and power transmitted by a moving chain in the field of tensiometer, power meter, and bicycle power meter design.BRIEF DESCRIPTION OF THE FIGURES

[0003] FIGURE 1A is a schematic representation of one variant of a power meter for a chain driven vehicle.

[0004] FIGURE IB is a schematic representation of one variant of the bicycle power meter engaged with a roller chain.

[0005] FIGURE 2 is a schematic representation of one variant of a power meter.

[0006] FIGURE 3 is a schematic representation of one variant of a chain tensiometer.

[0007] FIGURE 4 is a schematic representation of one variant of the power meter engaged with a bicycle.

[0008] FIGURE 5A is a schematic representation of one variant of a chain channel.

[0009] FIGURE 5B is a schematic representation of one variant of the chain channel engaged with a roller chain.

[0010] FIGURE 6 is a schematic representation of one variant of the chain channel.

[0011] FIGURE 7 is a schematic representation of one variant of a sensing bracket of the power meter.

[0012] FIGURE 8 is a schematic representation of one variant of the sensing bracket of the power meter.

[0013] FIGURE 9 is a schematic representation of one variation of the chain speed sensor of the power meter.BKON-M01-PCT

[0014] FIGURE 10 is a schematic representation of one variation of the retention assembly of the power meter.DESCRIPTION OF THE EMBODIMENTS

[0015] The following description of embodiments of the invention is not intended to limit the invention to these embodiments but rather to enable a person skilled in the art to make and use this invention. Variants, variations, configurations, embodiments, implementations, example implementations, and examples described herein are optional and are not exclusive to the variants, variations, configurations, embodiments, implementations, example implementations, and examples they describe. The invention described herein can include any and all permutations of these variants, variations, configurations, embodiments, implementations, example implementations, and examples.

[0016] Generally, the term “can,” as utilized herein, indicates an action or attribute of the system, which may or may not be executed by or be applicable to the system depending on the implementation or embodiment of the system.

[0017] Generally, the term “include,” as utilized herein, can mean “comprise,” “consist of,” or “consist essentially of,” and is not restricted to any one of the above interpretations throughout.

[0018] Generally, the term “a set of,” as utilized herein, refers to one or more of the subject objects. Additionally, the terms “first,” “second,” “third,” etc., as utilized herein, do not imply an order but simply identify multiple instances of a step or component unless an order or series is otherwise implied.

[0019] Generally, the terms “planar,” “symmetric,” “coaxial,” “parallel,” “perpendicular,” and other terms characterizing the relative position defining characteristics of physical objects, as utilized herein, describe substantial adherence to the aforementioned concepts within mechanical tolerances. For example, if one component is “coaxial” with another, this indicates that the central axes of these components are aligned within a predefined tolerance. However, these components may define slightly different central axes relative to each other (e.g., due to play in an interface between these components, elasticity, and / or thermal expansion).

[0020] Generally, the term “bicycle,” as utilized herein, can refer to any chain-driven vehicle, including but not limited to electrically assisted bicycles, recumbent bicycles, tricycles, motorized bicycles, motorized scooters, and motorcycles.BKON-M01-PCT

[0021] Generally, the term “bicycle chain,” as utilized herein, refers to any roller chain that is configured for use in a bicycle drivetrain. Features described herein with respect to a bicycle chain are equally applicable to any roller chain including chain rollers, inner plates, and outer plates.

[0022] Generally, the terms “longitudinal,” “lateral,” and “vertical,” as utilized herein, refer to axes and dimensions defined relative to an intended orientation of a chain within the chain channel of the bicycle power meter, and are not intended to limit the power meter to a particular orientation relative to an external reference frame. The “longitudinal” axis or dimension, as utilized herein, refers to an axis parallel to the direction of chain translation within the chain channel. The “lateral” axis or dimension, as utilized herein, refers to an axis parallel to the roller pins of the chain when the chain is translating through the chain channel. The “vertical” dimension, as utilized herein, refers to an axis perpendicular to both the longitudinal axis and the lateral axis as defined above.

[0023] Generally, the term “sensing bracket” refers to a U-shaped bracket, including a base section and two flanges extending in the same direction that defines a chain channel internally within the bracket.

[0024] Generally, the term “bicycle power meter,” as utilized herein, is interchangeable with the term “power meter” except with respect to features specifically adapted to bicycles. Thus, features described with respect to the “power meter” may also apply to a “bicycle power meter.”

[0025] Generally, the terms “chain” and “roller chain” are utilized interchangeably throughout. Thus, any mention of a “chain” can be interpreted as applying to a roller chain including pins, rollers, inner links, and outer links.

[0026] The systems and methods described herein can be embodied and / or implemented at least in part as a machine configured to receive a computer-readable medium storing computer-readable instructions. The instructions can be executed by computer-executable components integrated with the application, applet, host, server, network, website, communication service, communication interface, hardware / firmware / software elements of a user computer or mobile device, wristband, smartphone, or any suitable combination thereof. Other systems and methods of the embodiment can be embodied and / or implemented at least in part as a machine configured to receive a computer-readable medium storing computer-readableBKON-M01-PCTinstructions. The instructions can be executed by computer-executable components integrated by computer-executable components integrated with apparatuses and networks of the type described above. The computer-readable medium can be stored on any suitable computer-readable media, such as RAMs, ROMs, flash memory, EEPROMs, optical devices (CD or DVD), hard drives, floppy drives, or any suitable device. The computer-executable component can be a processor, but any suitable dedicated hardware device can (alternatively or additionally) execute the instructions.

[0027] As a person skilled in the art will recognize from the following detailed description and from the figures and claims, modifications and changes can be made to the embodiments of the invention without departing from the scope of this invention as defined in the claims.1. Power Meter for a Chain-Driven Vehicle

[0028] As shown in FIGURE 1A and FIGURE IB, a power meter for a chain-driven vehicle (hereinafter, “the power meter 100”) includes: a chain channel 110; a sensing bracket 120; a strain gauge 130; and a chain speed sensor 140. The chain channel 110: is characterized by a channel path 112 defining a chain inlet 114, a convex deviation 116, and a chain outlet 119; includes a pair of vertically opposing ridges 113 extending along the channel path 112, each vertically opposing ridge in the pair of vertically opposing ridges 113 characterized by a ridge width less than an inner width of a chain of the chain driven vehicle; and is characterized by a channel height between the pair of vertically opposing ridges 113 greater than or equal to a roller diameter of the chain of the chain-driven vehicle. The sensing bracket 120: spans the pair of vertically opposing ridges 113; and is configured to measurably deflect in response to a force applied by the chain of the chain-driven vehicle to the pair of vertically opposing ridges 113. The strain gauge 130 is configured to measure deflection of the sensing bracket 120. The chain speed sensor 140 is configured to measure a speed of the chain of the chain-driven vehicle translating through the chain channel 110.

[0029] In one variant of the power meter 100 includes, a structural housing 106 defining a chain channel 110 characterized by a channel path 112 that: spans the structural housing along a longitudinal dimension; defines a chain inlet 114; defines a convex deviation 116; defines a chain outlet 119 aligned with the chain inlet 114; and divides the structural housing into a convex side 122 exterior to the convex deviation 116 and a concave side 124 interior to the convex deviationBKON-M01-PCT116. The chain channel 110 also includes a pair of vertically opposing ridges 113 extending along the channel path 112, each vertically opposing ridge defining a ridge width less than an inner width of the chain of the chain-driven vehicle. Additionally, the chain channel 110 defines a channel height between the pair of vertically opposing ridges 113 greater than or equal to a roller diameter of the chain of the chain-driven vehicle.

[0030] The power meter 100 can also include a U-shaped bracket 120 within the structural housing, wherein the U-shaped bracket includes: an anchoring flange 126 configured to anchor the U-shaped bracket to the structural housing at the convex side 122; and a force-sensitive flange 128 opposite the structural flange arranged within the housing at the concave side 124, and configured to measurably and elastically deflect in response to force applied to the convex deviation 116.

[0031] The power meter 100 can additionally include: a strain gauge 130 configured to detect deflection of the force-sensitive flange 128; a chain speed sensor 140 configured to measure a speed of the chain of the chain driven vehicle translating through the chain channel 110; a retention assembly 150 coupled to the structural housing and configured to attach to a front derailleur of the chain-driven vehicle (e.g., a bicycle, an electric bicycle, a tricycle), as shown in FIGURE 4; and a computing device configured to sample the strain gauge 130 and the chain speed sensor 140 to calculate a power transmitted via the chain of the chain-driven vehicle translating through the chain channel 110.2. Power Meter

[0032] As shown in FIGURE 2, the power meter 100 described above can be modified to function as a widely applicable power meter 102 for moving roller chains associated with systems other than chain-driven vehicles. More specifically, the power meter 102 includes the chain channel 110, the sensing bracket 120, the strain gauge 130, and the chain speed sensor 140. The chain channel 110: is characterized by a channel path 112 defining a chain inlet 114, a convex deviation 116, and a chain outlet 119; includes a pair of vertically opposing ridges 113 extending along the channel path 112, each vertically opposing ridge in the pair of vertically opposing ridges 113 characterized by a ridge width less than an inner width of a roller chain; and is characterized by a channel height between the pair of vertically opposing ridges 113 greater than or equal to a roller diameter of the roller chain. The sensing bracket 120: spans the pair ofBKON-M01-PCTvertically opposing ridges 113; and is configured to measurably deflect in response to a force applied by the roller chain to the pair of vertically opposing ridges 113. The strain gauge 130 is configured to measure deflection of the sensing bracket 120. The chain speed sensor 140 is configured to measure a speed of the roller chain translating through the chain channel 110.

[0033] In one variant, the power meter 102 further includes a computing device configured to sample the strain gauge 130 and the chain speed sensor 140 to calculate a power transmitted via the roller chain translating through the chain channel 110.3. Chain Tensiometer

[0034] As shown in FIGURE 3, the power meter 100 described above can be modified to function as a widely applicable chain tensiometer 106 for moving chains (hereinafter “chain tensiometer 106”). More specifically, the chain tensiometer 106 includes the chain channel 110, the sensing bracket 120, and the strain gauge 130. The chain channel 110: is characterized by a channel path 112 defining a chain inlet 114, a convex deviation 116, and a chain outlet 119; includes a pair of vertically opposing ridges 113 extending along the channel path 112, each vertically opposing ridge in the pair of vertically opposing ridges 113 characterized by a ridge width less than an inner width of a roller chain; and is characterized by a channel height between the pair of vertically opposing ridges 113 greater than or equal to a roller diameter of the roller chain. The sensing bracket 120: spans the pair of vertically opposing ridges 113; and is configured to measurably deflect in response to a force applied by the roller chain to the pair of vertically opposing ridges 113. The strain gauge 130 is configured to measure deflection of the sensing bracket 120.

[0035] In one variant, the chain tensiometer 106 includes a computing device configured to sample the strain gauge to calculate a chain tension of the roller chain translating through the chain channel 110.

[0036] In another variant, the chain tensiometer 106 includes a structural housing defining a chain channel 110 characterized by a channel path 112 that: spans the structural housing along a longitudinal dimension; defines a chain inlet 114; defines a convex deviation 116; defines a chain outlet 119 aligned with the chain inlet 114; and divides the structural housing into a convex side 122 exterior to the convex deviation 116 and a concave side 124 interior to the convex deviationBKON-M01-PCT116. The chain channel 110 also includes a pair of vertically opposing ridges 113 extending along the channel path 112, each vertically opposing ridge defining a ridge width less than an inner width of a chain. Additionally, the chain channel 110 defines a channel height between the pair of vertically opposing ridges 113 greater than or equal to a roller diameter of the chain.

[0037] The chain tensiometer 106 can also include a sensing bracket 120 within the structural housing, wherein the sensing bracket 120 includes: an anchoring flange 126 configured to anchor the sensing bracket 120 to the structural housing at the convex side 122; and a force-sensitive flange 128 opposite the structural flange arranged within the housing at the concave side 124, and configured to measurably and elastically deflect in response to force applied to the convex deviation 116.

[0038] The chain tensiometer 106 can additionally include: a strain gauge 130 configured to detect deflection of the force-sensitive flange 128; a retention assembly 150 coupled to the structural housing and configured to maintain a position of the structural housing in a direction of chain translation; and a computing device configured to sample the strain gauge 130 to calculate a tension of the chain translating through the chain channel 110.4. Applications

[0039] As shown in FIGURE IB and FIGURE 5B, the power meter 100 is configured to be positioned around a roller chain and, in some implementations, transiently attached to a front derailleur of a chain-driven vehicle, such as a bicycle, between the front chainring and the rear cassette to measure the tension, speed, and power transmitted through the chain. More specifically, the power meter 100 includes a chain channel 110 with a convex deviation 116 that causes a chain placed within the channel to exert a measurable bidirectional force against both sides of the chain channel 110, approximately perpendicular to the chain’s direction, sufficient to measure the tension of the chain while the chain is in motion. The power meter 100 also includes a chain speed sensor 140 capable of detecting the speed of the chain as the chain moves through the chain channel 110. Given the tension and speed of the chain, the power meter 100 can utilize an onboard computing device to calculate the power transmitted by the chain. The power meter 100 offers similar accuracy to existing power meters, such as pedal-, crank-, chainring-, or hub-based power meters, while enabling a significantly improved installation experience thatBKON-M01-PCTdoes not require disassembly or replacement of previously installed components of the chain-drive vehicle.

[0040] In one application, a user may install the power meter 100 in two simple steps by attaching the chain to a bicycle’s or similar chain-driven vehicle’s front derailleur (or frame for vehicles without a front derailleur) via the retention assembly 150 and by guiding the chain through the chain channel 110. Once installed, the power meter 100 is allowed to follow the direction of the chain during gear changes or other movements based on articulation of the retention assembly 150 relative to an attachment point on the chain-driven vehicle. Thus, upon installation, the power meter 100 is constrained in the direction of chain movement while maintaining continuous alignment of the chain channel 110 with the chain, thereby reducing friction between the chain and the power meter 100 and improving measurement accuracy.

[0041] In another application, the power meter 100 utilizes few components and even fewer moving components, thereby facilitating manufacturing and reducing unit cost. Additionally, the power meter 100 is a standalone component and therefore does not require integration with any load-bearing component that forms part of a train driven vehicle's transmission (e.g., pedal, crank, chainring, bottom bracket, rear hub). Thus, the power meter 100 can be designed minimally without sacrificing the functionality of the chain-driven vehicle.

[0042] In yet another application, because the power meter 100 is stable relative to the frame of the chain-driven vehicle (i.e., moving slightly due to articulation of the retention assembly 150 and movement of the front derailleur) unlike existing power meters, the power meter 100 can include additional sensors such as accelerometers, gyroscopes, and magnetometers, which can be utilized to detect additional metrics associated with the operation of the chain-driven vehicle. For example, the power meter 100 can provide data such as power, left / right balance, cadence, torque, power phase, torque efficiency, pedal smoothness, gradient (or pitch angle of the chain-driven vehicle), acceleration while turning or otherwise, lean angle, and more. Thus, the power meter 100 can function as a central data-gathering hub attached to the chain-driven vehicle.

[0043] In yet another application, the power meter 100 can be installed on a chain-driven vehicle to provide power data to a user for the purpose of training or improving fitness. Additionally or alternatively, the power meter 100 can communicate with a control unit of an electrically assistedBKON-M01-PCTchain-driven vehicle to enable pedal assist functionality. Furthermore, in some applications, the power meter 100 can be installed on any other vehicle or device utilizing pin-and-roller chains to measure either tension, power, or both.5. Structural Housing

[0044] Generally, the power meter 100 includes a structural housing that defines an external structure of the power meter 100, structurally supports components such as the sensing bracket 120 and the computing device (e.g., implemented as a printed circuit board, hereinafter “PCB”), and prevents ingress of debris, water, and other potential contaminants. More specifically, the structural housing is constructed from a rigid material or combination of materials, including but not limited to polyurethane, ABS plastic, stainless steel, aluminum, or carbon fiber. The structural housing can be constructed via additive manufacturing, injection molding, or any other method consistent with the selected materials.

[0045] In one implementation, the structural housing can define both sides or one side of the chain channel 110, which runs longitudinally across the structural housing and splits the structural housing into two distinct sections, including a convex side 122 and a concave side 124, defined based on the direction of the convex deviation 116 of the chain channel 110.

[0046] In another implementation, the structural housing contains and / or maintains the relative positions of components. For example, the structural housing can position the sensing bracket 120 relative to the chain speed sensor 140 to enable the chain speed sensor 140 to detect the speed of the chain translating through the chain channel 110.

[0047] In yet another implementation, the structural housing provides a hollow internal volume within which the computing device and a battery are arranged, as well as a set of bracket attachment points (e.g., bracket slots) that position the sensing bracket 120 on either side of the chain channel 110 or to form the chain channel 110. In one example of this implementation, the structural housing can be characterized by a two-piece construction including an interior section defining the chain channel 110 and a set of bracket slots, and an exterior section defining a cavity configured to contain the computing device, a battery, and / or other components when coupled to the interior section. In this example implementation, the power meter 100 is assembled by inserting the sensing bracket 120 into the set of bracket slots and sandwiching the sensing bracket 120 against the exterior section by the interior section, with the internal components ofBKON-M01-PCTthe power meter 100 disposed within the cavity of the exterior section. Alternatively, in implementations in which the sensing bracket 120 itself defines the chain channel 110, the structural housing can securely couple to the sensing bracket 120 via any fastening mechanism, including adhesive fastening, bolts or screws, or interference fits.

[0048] Additionally, in this example implementation, the structural housing can couple with the retention assembly 150 by defining a socket in a ball-and-socket joint around a retention rod 153. In this example implementation, the exterior section of the structural housing and the interior section of the structural housing can be attached via any suitable fastener or coupled together via a snap or press-fit. Thus, in this example implementation, the structural housing is easy to manufacture and assemble, thereby decreasing the cost of manufacturing the power meter 100.

[0049] In implementations in which the chain channel 110 is defined by the structural housing, the structural housing can include an aperture or opening aligned with the chain channel 110, thereby decreasing noise resulting from the chain running against the chain channel 110.

[0050] For a chain roller variant of the speed sensor, the structural housing can include a cutout or cavity adjacent to the chain channel 110, thereby enabling a chain roller to rotate within the cavity or cutout while engaged with a chain translating through the chain channel 110.

[0051] For a magnetometer variant of the speed sensor, the structural housing can be configured to additionally contain a magnetometer 142 or a PCB including the magnetometer 142, as well as a magnet 144 arranged within the structural housing such that the magnetometer 142 is capable of measuring magnetic field variations due to the movement of the chain through the chain channel 110.5.1. Chain Channel

[0052] As shown in FIGURE 5 A, FIGURE 5B, and FIGURE 6, a chain channel 110 is configured to hold the chain between the convex side 122 and the concave side 124 of the chain channel 110 as the chain translates due to the operation of the chain-driven vehicle or chain-operating device. Additionally, the chain channel 110 is shaped according to a channel path 112 such that, in response to tension applied to the chain, a measurable force is applied to both the convex side 122 of the structural housing and the concave side 124 of the chain channel 110 approximately perpendicular to the direction of chain translation. The power meter 100 is configured to measure strain (via one or more strain gauges 130) in the sensing bracket 120BKON-M01-PCTcaused by this force to correlate this strain with tension in the moving chain. More specifically, the chain channel 110 defines an internal geometry including a pair of vertically opposing ridges 113 arranged on the opposing vertical faces of the chain channel 110 (i.e., one on the convex side 122 of the chain channel 110 and the other on the concave side 124 of the chain channel 110).

[0053] In one implementation, the chain channel 110 is defined by the sensing bracket 120, such that the sensing bracket 120 defines the pair of vertically opposing ridges 113 and bridges the gap between the vertically opposing ridges 113 on one lateral side of the chain channel 110, as is shown in FIGURE 7, and further described below with respect to the sensing bracket 120.

[0054] In another implementation, the chain channel 110 is defined by the structural housing, which includes the sensing bracket 120 within the structural housing, spanning the chain channel 110 on one lateral side such that the sensing bracket 120 deflects in response to force applied to either or both of the pair of vertically opposing ridges 113, as is shown in FIGURE 8.

[0055] In yet another implementation, the chain channel 110 is open on the interior lateral side of the structural housing to enable a user to more easily slide the chain into the chain channel 110 (e.g., with the exterior section of the structural housing at least partially enclosing the exterior lateral side of the chain channel 110). Additionally, by leaving the interior lateral side of the chain channel 110 open, this implementation minimizes interference with components of the chain-driven vehicle disposed interior to the chain, such as a chain stay, a tire of a rear wheel, and / or a rear suspension.

[0056] Alternatively, the chain channel 110 is at least partially enclosed on both the interior lateral side and the exterior lateral side, such that a chain translating through the chain channel 110 passes between the interior section and exterior section of the structural housing. Thus, in this implementation, the power meter 100 exhibits increased structural strength at the expense of potential interference with components of the bicycle and / or installation complexity.

[0057] In yet another implementation, the power meter 100 includes an external chain guide configured to transiently and at least partially traverse the chain channel 110 on either the interior or exterior lateral side of the chain channel 110, as shown in FIGURE 1A. More specifically, the external chain guide can extend and retract across the chain channel 110 via friction-, latch-based, or any other mechanism that enables transient extension or retractions across an open lateral side of the chain channel 110 to prevent external lateral dislocation of the chain fromBKON-M01-PCTthe chain channel 110. In particular, the power meter 100 can include an external chain guide configured to transiently traverse the chain channel 110 and configured to prevent external lateral dislocation of the bicycle chain out of the chain channel 110.

[0058] Generally, the chain channel 110 defines a lateral width sufficient for the vertically opposed ridges to hold the chain within the channel and elastically transmit forces applied by the chain without causing the chain to regularly contact either lateral side of the chain channel 110 or an external chain guide 162 or an internal chain guide 160 on either side of the chain channel 110. More specifically, in implementations configured for engagement with a range of standardized bicycle chains, the chain channel 110 is characterized by a lateral width between 4 millimeters and 10 millimeters.

[0059] Generally, the chain channel 110 defines a channel height sufficient to enable the chain to pass between the concave side 124 and the convex side 122 of the chain channel 110. In implementations configured for engagement with a range of standardized bicycle chains, the channel height is between 12 millimeters and 15 millimeters.5.1.1. Channel Path

[0060] As shown in FIGURE 6, the chain channel 110 is characterized by a linear channel path 112 that spans the length of the structural housing in a longitudinal dimension and includes a central convex deviation 116, thereby dividing the chain channel 110 into the aforementioned concave side 124 and convex side 122 linked by a backing on at least one lateral side of the chain channel 110. More specifically, the channel path 112 defines: a chain inlet 114; a convex deviation 116; and a chain outlet 119 aligned (i.e., colinear) with the chain inlet 114. Additionally, the channel path 112 can also define transitional radii between the linear inlet, the convex deviation 116, and the linear outlet to smoothly transition the chain between regions of the chain channel 110 as the chain translates. Thus, the chain channel 110 can be swept out from the structural housing or defined by the sensing bracket 120.

[0061] In an implementation configured to engage with a range of standard bicycle chains, the chain channel 110 can define a longitudinal dimension greater than 40 millimeters. In this implementation, the chain channel 110 can define a longitudinal dimension of less than 300 millimeters. In one example, the chain channel 110 can define a longitudinal dimension between 90 millimeters and 120 millimeters.BKON-M01-PCT

[0062] In one implementation, at each longitudinal point of the channel path 112, the convex side 122 of the chain channel 110 is symmetric with the concave side 124 of the chain channel 110 about a lateral axis passing through the channel path 112. Alternatively, the chain channel 110 can define small deviations in symmetry about the lateral axis extending through the channel path 112 to reduce friction, noise, or longitudinal forces exerted by the translating chain on the structural housing.

[0063] The chain inlet 114 is configured to accept the chain as the chain enters the chain channel 110 while reducing vibration and friction with the chain. The chain inlet 114 provides some longitudinal space for rollers of the chain to come into contact with one of the vertically opposing ridges 113 of the chain channel 110 and begin to roll along this vertically opposing ridge. In one implementation, the chain inlet 114 defines a length between 10 millimeters and 60 millimeters.

[0064] In one implementation, the channel path 112 defines an inlet transitional region smoothly connecting the chain inlet 114 to the convex deviation 116. In this implementation, the inlet transitional region is characterized by an inlet transitional radius between 50 and 75 percent of the radius characterizing the convex deviation 116 and a concavity opposite to the convex deviation 116.

[0065] The convex deviation 116 of the channel path 112 is characterized by a radius, a chord length, and / or a sagitta 117 (relative to a line defining the chain inlet 114 and chain outlet 119).

[0066] Generally, the convex deviation 116 is characterized by a sagitta 117 configured to cause the chain rollers to come into contact with the vertically opposing ridge on the concave side 124 of the chain channel 110 on either side of the convex deviation 116 in the longitudinal dimension. More specifically, in implementations configured for engagement with a range of standardized bicycle chains, the convex deviation 116 is characterized by a sagitta 117 or vertical offset between 0.5 millimeters and 10 millimeters based on the radius and chord length of the convex deviation 116, with greater radii and chord lengths corresponding to a greater sagitta 117. In one example implementation, the convex deviation 116 is characterized by a sagitta 117 between 5 millimeters and 6 millimeters. In another example implementation, the convex deviation 116 defines a flat surface 118 vertically offset from the chain inlet 114 by at least 0.5 millimeters (i.e., vertically offset from a lower surface of the chain inlet 114). In yet anotherBKON-M01-PCTexample implementation, the convex deviation 116 defines a sagitta 117 greater than or equal to 0.5 millimeters.

[0067] Additionally, the convex deviation 116 is characterized by a radius configured to smooth the vertical shift of the chain as the chain passes over the convex deviation 116 without distributing the force that the chain applies to the convex deviation 116 over an excessively wide area, such that this force is not measurable by the strain gauge 130. More specifically, in implementations configured for engagement with a range of standardized bicycle chains, the convex deviation 116 is characterized by a radius between 20 millimeters and 200 millimeters. In one example implementation, the convex deviation 116 is characterized by a radius between 55 millimeters and 65 millimeters.

[0068] Furthermore, the convex deviation 116 is characterized by chord length, which describes the longitudinal extent of the convex deviation 116 within the channel path 112. More specifically, in implementations configured for engagement with a range of standardized bicycle chains, the chord length of the convex deviation 116 is greater than 20 millimeters. In one example implementation, the convex deviation 116 is characterized by a chord length between 50 and 60 millimeters.

[0069] In yet another implementation, the channel path 112 defines a convex deviation 116 characterized by a flat surface 118 instead of a consistent radius across the chord length of the convex deviation 116. In this implementation, the convex deviation 116 includes a radiused section on either side of the flat surface 118. More specifically, the convex deviation 116 can define a flat surface 118 characterized by a length equal to or greater than the pitch of the roller chain. In particular, the convex deviation 116 can define a flat surface 118 characterized by a length greater than 12.7 millimeters for compatibility with standard bicycle chains. Thus, in this implementation, the convex deviation 116 defines a flat surface 118 to enable a more consistent application of vertical force as rollers of the chain pass over the convex deviation 116.

[0070] A person of skill in the art will understand that the sagitta 117, radius, and chord length of the convex deviation 116 are geometrically related, such that two of the three parameters may be selected based on design priorities, which can then define the remaining parameters.

[0071] In one implementation, the channel path 112 defines an outlet transitional region, similar to the inlet transitional region, which smoothly connects the convex deviation 116 to the chainBKON-M01-PCToutlet 119. In this implementation, the outlet transitional region is characterized by an outlet transitional radius between 50 and 75 percent of the radius characterizing the convex deviation 116 and a concavity opposite to the convex deviation 116.

[0072] The chain inlet 114 is configured to guide the chain while exiting the chain channel 110, thereby reducing vibration and friction with the chain. The chain outlet 119 provides some longitudinal space for rollers of the chain to disengage with one of the vertically opposing ridges 113 of the chain channel 110 by limiting any oscillation of the chain as the chain exits the chain channel 110. In one implementation, the chain outlet 119 defines a length between 10 millimeters and 60 millimeters.5.1.2. Vertically Opposing Ridges

[0073] As shown in FIGURE 5A, the chain channel 110 includes a pair of vertically opposing ridges 113 extending along the channel path 112, each ridge defining a ridge width less than an inner width of the chain (e.g., the distance between the inner plates of the roller chain). More specifically, the pair of vertically opposing ridges 113 are configured to maintain the lateral alignment of the chain with the power meter 100 and transmit measurable force from the translating chain to be detected by the strain gauge 130, while minimizing noise, vibration, and longitudinal force applied to the power meter 100. In implementations configured for engagement with a range of standardized bicycle chains, each vertically opposing ridge can define a vertical ridge width between 1.75 millimeters and 2.25 millimeters and a vertical ridge height of 2.25 to 2.75 millimeters.

[0074] Additionally, the vertical ridge height and channel height together define the channel opening, which is greater than the diameter of the chain rollers. In implementations configured for engagement with a range of standardized bicycle chains, the channel opening is characterized by a height between 8 millimeters and 9 millimeters.

[0075] In one implementation, the vertically opposing ridges 113 are defined by or integrated with the sensing bracket 120, thereby transmitting force applied to the vertically opposing ridges 113 by the translating ridges directly to the strain gauge 130 arranged on the sensing bracket 120 via the structure of the sensing bracket 120.BKON-M01-PCT

[0076] In another implementation, the vertically opposing ridges 113 are characterized by an inlet and outlet chamfer, thereby reducing longitudinal forces applied to the power meter 100 by the translating chain.

[0077] In yet another implementation, either of the vertically opposing ridges 113 can be lined with a dampening material, such as rubber or silicone, at a leading edge of each vertically opposing ridge or further along the length of the vertically opposing ridge.

[0078] In yet another implementation, each vertically opposing ridge or the entire chain channel 110 can be instantiated as a replaceable component configured to engage with the structural housing. In one example, the pair of vertically opposing ridges 113 are defined by a replaceable sensing bracket 120, which may be removed from the structural housing and replaced with a second instance of the sensing bracket 120 upon being worn down during use. In another example, the pair of vertically opposing ridges 113 is implemented as two separate components from both the structural housing and the sensing brackets 120 and may be replaced without replacement of either the structural housing or the sensing bracket 120. Thus, as the pair of vertically opposing ridges 113 wear during usage of the power meter 100, a user may eventually replace each vertical opposing ridge or the entire chain channel 110.6. Sensing Bracket

[0079] Generally, the power meter 100 includes a sensing bracket 120 coupled to the structural housing that spans the chain channel 110. In one implementation, shown in FIGURE 7, the sensing bracket 120 defines the pair of vertically opposing ridges 113 on both sides of the chain channel 110, thereby directly receiving force from the translating chain and measurably deflecting (via a strain gauge 130 arranged on the sensing bracket 120) as the chain traverses the convex deviation 116 of the chain channel 110. In this implementation, the sensing bracket 120 is coupled to the structural housing via a fastening mechanism. In another implementation, shown in FIGURE 8, the sensing bracket 120 defines an anchoring flange 126 on the concave side 124 of the structural housing and a force-sensitive flange 128 integrated with the convex side 122 of the structural housing. In this implementation, the sensing bracket 120 is configured to receive force applied to the vertically opposing ridges 113 of the chain channel 110, which are then transmitted through the structural housing to the sensing bracket 120. The sensing bracket 120 is configured to measurably deflect, thereby enabling the computing system to calculate the tensionBKON-M01-PCTof the chain based on the measured force and the geometry of the chain channel 110. The sensing bracket 120 can be constructed from a substantially rigid but ductile and elastic material, such as stainless steel or aluminum.

[0080] In implementations of the sensing bracket 120 in which the bracket is integrated with the structural housing, the sensing bracket 120 is configured such that the anchoring flange 126 and the force-sensitive flange slot 129 into respective bracket slots located on the interior section of the structural housing. The sensing bracket 120 can then be locked into place between the interior section and the exterior section of the structural housing.

[0081] In another implementation, the sensing bracket 120 is constructed from a single piece of sheet material cut and formed to specified dimensions. In this implementation, the anchoring flange 126 and the force-sensitive flange 128 can be formed via a press brake.

[0082] In yet another implementation, the sensing bracket 120 can define bores positioned to impart specific deflection characteristics of the sensing bracket 120, especially the force-sensitive flange 128. In one example of this implementation, the sensing bracket 120 defines a bore located along the bend radius between a central section of the sensing bracket 120 and the force-sensitive flange 128, thereby decreasing the moment of cross-sectional area of the flange and increasing the deflection of the force-sensitive flange 128 in response to chain-applied forces.

[0083] In yet another implementation, the sensing bracket 120 can define an aperture laterally aligned with the channel and with an aperture in the structural housing. In this implementation, the apertures prevent resonance of the U-shaped bend and the structural housing with vibrations produced by the chain translating through the chain channel 110.6.1. Anchoring Flange

[0084] In implementations in which the sensing bracket 120 is integrated within the structural housing, the anchoring flange 126 is securely coupled to the structural housing, thereby preventing displacement of the sensing bracket 120 from the structural housing even during deflection caused by chain-applied forces. The anchoring flange 126 is configured to fit securely into an anchoring flange slot 127 within the structural housing and can be secured via an interference fit between the anchoring flange 126 and the structural housing or by any fastening mechanism. In one implementation, the anchoring flange 126 is arranged within the concaveBKON-M01-PCTsection of the structural housing. In yet another implementation, the anchoring flange 126 extends from the central plane of the sensing bracket 120 substantially perpendicularly toward the interior side of the power meter 100.6.2. Force-Sensitive Flange

[0085] In implementations in which the sensing bracket 120 is integrated with the structural housing, the force-sensitive flange 128 is configured to deflect in response to forces applied by the chain to the convex deviation 116 of the chain channel 110. More specifically, the force-sensitive flange 128, arranged on the convex section of the structural housing near the convex deviation 116 of the chain channel 110, defines a lower moment of cross-sectional area than the anchoring flange 126, thereby enabling the force-sensitive flange 128 to deflect in response to forces applied to the convex deviation 116. Thus, when force is applied by the chain over the convex deviation 116, the convex section of the structural housing transmits force to the force-sensitive flange 128, which then deflects, thereby generating a signal at the strain gauge 130.6.3. Chain-Channel Defining Implementations

[0086] As shown in FIGURE 7, the sensing bracket 120 can define the chain channel 110 and the pair of vertically opposing ridges 113 of the chain channel 110 via the geometry of the sensing bracket 120 itself. More specifically, in these implementations, instead of a U-shaped structure defining the anchoring flange 126 and force-sensitive flange 128, the sensing bracket 120 can define an enclosed C-shaped structure, such that each flange of sensing bracket 120 defines the pair of vertically opposing ridges 113 and the shape of the chain channel 110. In particular, in this implementation, the sensing bracket 120 defines the chain channel 110; and the pair of vertically opposing ridges 113 extend from a pair of vertically opposing flanges of the sensing bracket 120. Thus, in this implementation, the sensing bracket 120 receives force applied to the pair of vertically opposing ridges 113 by the chain directly, instead of through the material of the structural housing.

[0087] In this implementation, the sensing bracket 120 can mount external to the structural housing to facilitate occasional replacement of the sensing bracket 120 (after sufficient wear occurs on the pair of vertically opposing ridges 113) without requiring disassembly of the structural housing. Additionally, in this implementation, the dimensions and material of theBKON-M01-PCTstructural housing is reduced as the structural housing does not span the chain channel 110 or fully enclose the sensing bracket 120. Thus, the sensing bracket 120 can transiently mount to the structural housing to enable easy replacement and more accurate sensing capabilities.7. Bracketless Variants

[0088] In some variants, the power meter 100 does not include a sensing bracket 120 and instead measures tension in the translating chain based on deflection or deformation of the structural housing itself. In this variant, the structural housing can define a region of the convex section configured to measurably deflect in response to force applied by the translating chain under tension. Additionally, in this variant, the structural housing can include additional reinforcement between the convex section and the concave section to ensure force applied to the convex side 122 and the concave side 124 of the chain channel 110 are accurately measurable by the set of strain gauges 130 or other force sensors.8. Strain Gauges

[0089] As shown in FIGURE 8, a strain gauge 130 or set of strain gauges 130 is coupled to the sensing bracket 120 and configured to detect deflection of the sensing bracket 120 in response to forces transmitted from the chain within the chain channel 110. More specifically, the set of strain gauges 130 can include electrical resistance strain gauges (e.g., foil strain gauges, wire strain gauges, semiconductor strain gauges), optical strain gauges, piezoelectric strain gauges, or any other type of strain gauge. Additionally, the set of strain gauges 130 is configured to communicate with computing devices via digital or analog electrical signals.

[0090] In one implementation, the set of strain gauges 130 is centrally coupled to a face of the force-sensitive flange 128 vertically aligned with the apex of the convex deviation 116. In this implementation, the strain gauge 130 is positioned over the point likely to deflect most in response to forces applied to the convex deviation 116.

[0091] In another implementation, the set of strain gauges 130 is arranged and electrically coupled in a full bridge configuration, thereby improving the temperature compensation of the set of strain gauges 130. Alternatively, the set of strain gauges 130 is arranged and electrically coupled in a Wheatstone bridge configuration.

[0092] In yet another implementation, shown in FIGURE 1A, the set of strain gauges 130 is positioned on the bridging panel of the bracket that traverses the chain channel 110. In thisBKON-M01-PCTimplementation, the bridging panel of the sensing bracket 120 is configured to deflect in response to forces applied by the chain under tension while translating through the chain channel 110.8.1. Additional Sensors in the Structural Housing

[0093] In some implementations, the power meter 100 can include alternative force sensors in addition to, or in replacement of, the set of strain gauges 130 arranged on the force-sensitive flange 128 of the sensing bracket 120 as described above. Generally, the power meter 100 can include force sensors, such as piezoelectric force sensors, capacitive force or displacement sensors, laser displacement sensors, linear variable differential transformers, optical interferometers, or hall effect sensors with an embedded magnet. Thus, the power meter 100 can utilize a variety of sensors or combinations of sensors to measure the force applied to both sides of the chain channel 110 by the translating chain under tension.

[0094] In one implementation, the power meter 100 includes a set of inertial sensors within the structural housing to detect the movement (i.e., vibration, rotation, translation) of the structural housing such that the computing device can sample this set of inertial sensors to denoise the signal of the strain gauge 130 or other force sensors.

[0095] In another implementation, the power meter 100 includes a temperature sensor, such as a resistance temperature detector, thermocouple, or thermistor, thereby enabling the computing device to correct for temperature changes at the power meter 100 that can change the physical properties of the system and, therefore, the values detected by the strain gauges 130 and / or other force and displacement sensors.9. Chain Speed Sensor

[0096] Generally, the power meter 100 includes a chain speed sensor 140 electrically coupled to the computing device and configured to measure the speed of the chain translating through the chain channel 110, thereby enabling the computing device to calculate power from the tension detected by the set of strain gauges 130. More specifically, the chain speed sensor 140 is arranged around the chain channel 110 in order to interact with the chain to detect the speed of the chain. In chain tensiometer 106 variants not configured to measure power, the chain speed sensor 140 can be excluded from the chain tensiometer 106.BKON-M01-PCT

[0097] As shown in FIGURE 1 A, the power meter 100 can include a chain roller variant of the chain speed sensor 140. More specifically, the chain roller variant of the chain speed sensor 140 includes a chain roller configured to engage with a chain translating through the chain channel 110 within either the chain inlet 114 or the chain outlet 119 of the chain channel 110 and rotary encoder. In particular, the power meter 100 can include a speed sensor including a chain roller configured to rotate in response to translation of the chain through the chain channel 110. Thus, in this implementation, the chain translating through the chain channel 110 causes the chain roller to rotate at an angular speed measurable via the rotary encoder, which can then be converted into a linear speed of the chain by the computing device. Additionally or alternatively, an axle of the chain can be used to deliver power to the power meter 100 or charge the battery of the power meter 100 via a small electrical generator arranged about the axle. In one example of this implementation, the chain roller includes teeth of the chain roller including a flexible material configured to laterally deflect in response to insertion of the chain within the chain channel 110, such that the chain can be easily inserted into the chain channel 110 by transiently deflecting a tooth of the chain roller.

[0098] As shown in FIGURE 9, the power meter 100 can include a magnetometer variant of the chain speed sensor 140. More specifically, the magnetometer variant of the chain speed sensor 140 can include a magnet 144 positioned within the structural housing such that the magnetic field of the magnet passes through the chain channel 110 and a magnetometer 142 (i.e., Hall effect sensor) positioned with the structural housing such that disturbances in the magnetic field of the magnet are measurable by the magnetometer 142. In particular, the speed sensor can include a Hall effect sensor. In this variant, the magnetometer 142 can produce a high-fidelity cyclic signal representing the chain’s translation through the chain channel 110 without any moving parts. Additionally, in this variant, the computing device can detect chain wear by detecting small changes in the frequency spectrum of the cyclic signal produced by the magnetometer 142 over time, caused by lost material around the rollers.

[0099] In another variant, the power meter 100 can estimate a chain speed based on the periodicity of the tension measured via the set of strain gauges 130. In this variant, the power meter 100 can store a number of gear teeth for each of the front chainrings of the bicycles in order to correlate each tension cycle with a number of segments translated through the chainBKON-M01-PCTchannel 110. Thus, the computing device of the power meter 100 can calculate a chain speed based on the number of segments translated per pedal cycle. Although this variant reduces the complexity of the power meter 100 by obviating the need for a chain speed sensor 140, in some instances, the variant may require multiple pedal strokes to calculate a stable pedaling period based on tension measurements derived from the set of strain gauges 130. This effect may potentially decrease the accuracy of the power meter 100 during short bursts of pedaling.

[0100] In yet another variant, the power meter 100 can include a speed sensor including an optical sensor. In this variant, a laser- or LED-based optical sensor such as a photoelectric sensor (e.g., a through-beam, retroreflective, or diffuse sensor, a fiber-optic photoelectric sensor, a laser triangulation sensor, and / or an optical encoder). In this variant, the power meter 100 can integrate the optical sensor aperture within or near the chain channel 110 to detect the speed of the chain as the chain translates through the chain channel 110.10. Retention Assembly

[0101] As shown in FIGURE 10, the power meter 100 can include a retention assembly 150 configured to flexibly couple the structural housing to a chain-driven vehicle (e.g., a bicycle), such that the structural housing can adjust to small variations in lateral chain position and / or orientation due to gear changes or other factors, thereby maintaining alignment between the chain channel 110 and the chain. More specifically, the retention assembly 150 can include a retention interface 151 at the structural housing, a retention rod 153, and an attachment mechanism 152 152 configured to attach to the bicycle or vehicle. In particular, the power meter 100 can include a retention assembly 150 coupled to the structural housing and configured to substantially maintain a position of the chain channel 110 and the sensing bracket 120 in a direction of translation of the chain.

[0102] In one implementation, the retention assembly 150 is configured to flexibly couple the structural housing and the front derailleur of the bicycle such that, in response to a user shifting via the front derailleur, the power meter 100 moves laterally with the front derailleur, thereby maintaining alignment between the chain and the chain channel 110. More specifically, the retention assembly 150 is configured to transiently couple to a front derailleur of a bicycle at a distal end of the retention assembly 150, and coupled to structural housing at a proximal end of the retention assembly 150.BKON-M01-PCT

[0103] In another implementation, the retention assembly 150 is coupled to the structural housing via a ball-and-socket retention interface 151. More specifically, in this implementation, the structural housing can define a socket, and the retention rod 153 can define a ball at a proximal end relative to the structural housing. Thus, in this implementation, the structural housing is allowed to rotate about the ball-and-socket joint with multiple degrees of freedom, but is retained from translating longitudinally along the chain.

[0104] In yet another implementation, the retention assembly 150 includes a second ball-and-socket interface at the attachment mechanism 152, thereby enabling additional degrees of freedom at the structural housing about the second ball-and-socket interface.

[0105] In yet another implementation, the retention assembly 150 includes a second retention rod 153 parallel to the first retention rod 153 and configured to interface with additional ball-and-socket joints at each end of the second retention rod 153. Thus, in this implementation, the retention assembly 150 restricts the structural housing to rotate about a longitudinal access parallel to the chain, thereby preventing misalignment between the vertical axis of the chain and the vertical axis of the structural housing.

[0106] In yet another implementation, the retention assembly 150 can include ball-and-socket joints that define an axial peg each vertical pole of the ball to restrict rotation of the structural housing about the longitudinal axis, thereby maintaining vertical alignment between the chain and the chain channel 110. The retention assembly 150 can include a second ball-socket-joint at the opposite end of the retention rod 153 also defining an axial peg at each vertical pole to further constrain the rotation of the structural housing about the longitudinal axis. Additionally or alternatively, the retention assembly 150 can include hinges configured to rotate about a vertical axis in replacement of either or both ball-and-socket joints.

[0107] In yet another implementation, the power meter 100 can include a retention assembly 150 configured to attach to a frame of a chain-driven vehicle (e.g., a bicycle frame). More specifically, the power meter 100 can include a retention assembly 150 configured to transiently couple to a bicycle frame or the frame of a chain-driven vehicle. Thus, in this implementation, the structural housing of the power meter 100 is constrained in multiple degrees of freedom relative to the frame of the bicycle or chain-driven vehicle.BKON-M01-PCT

[0108] In yet another implementation, the power meter 100 can include a retention assembly 150 including a spring-loaded extension mechanism 154. In this implementation, the retention assembly 150 can include a spring-loaded extension mechanism 154 along the length of the retention assembly 150 configured to smooth impulses transmitted through the retention assembly 150 due to longitudinal forces applied to the power meter 100, thereby reducing the amount of force applied to the attachment mechanism 152.

[0109] Generally, the attachment mechanism 152 can include any mechanism sufficient to resist longitudinal forces applied to the power meter 100. For example, the attachment mechanism 152 can include a rubber strap and loop or clamp. Additionally, the attachment mechanism 152 can include an interface for engagement with the retention rod 153, such as a ball-and-socket joint. In one implementation, the attachment mechanism 152 is configured to attach to the front derailleur of a bicycle. For applications in which the bicycle or vehicle does not have a front derailleur, the attachment mechanism 152 can be configured to attach to any other frame element that does not translate or rotate in relation to the chain-based transmission of the vehicle, such as the chain stay or seat tube.11. Auxiliary Sensors

[0110] In one implementation, the attachment mechanism 152 can house a set of auxiliary sensors and magnetic sensors electrically coupled to the computing device wirelessly or via a wire supported by the retention assembly 150. For example, the attachment mechanism 152 can house accelerometers, gyroscopes, and magnetometers. In this implementation, the accelerometers and gyroscopes are attached to the frame of the bicycle and can therefore be utilized to measure forces acting on the frame and correlate these forces with various power- or pedaling-related metrics. In one implementation, the power meter 100 can utilize the set of auxiliary sensors to measure the lateral oscillation of the rider while pedaling the bicycle and / or other biomechanical metrics. In another implementation, the power meter 100 can detect cadence via a magnetometer housed by the attachment mechanism 152 by detecting the proximity of a magnet located on a pedal or crank arm of the bicycle. In yet another implementation, the power meter 100 can detect the gradient traversed by the bicycles based on a gravity vector measured by the set of auxiliary sensors. In yet another implementation, the power meter 100 can detect peak forces that occur during turning or linear acceleration of the bicycle. Thus, the power meterBKON-M01-PCT100 can leverage the stable position of the attachment mechanism 152 relative to the frame of the bicycle to calculate advanced metrics that cannot be measured without a secondary device with pedal-, crank-, chainring-, bottom bracket-, or hub-based power meters.12. Computing Device

[0111] Generally, the power meter 100 includes a computing device that is configured to periodically and / or repeatedly sample data from the set of strain gauges 130, the chain speed sensor 140, and / or the set of auxiliary sensors to calculate power metrics and / or other secondary metrics. More specifically, the power meter 100 can include a computing device configured to sample the strain gauge 130 and the chain speed sensor 140 to calculate a power transmitted via the chain (e.g., bicycle chain) translating through the chain channel 110. The computing device can also include a wireless transmitter, with which the computing device can communicate with a bicycle computer or head unit. Alternatively, the computing device can include a local storage device on which the computing device can store power data for subsequent upload to a bicycle computer, smartphone, tablet, laptop, or any other secondary computing device. More specifically, the computing device is configured to calculate metrics including but not limited to: power, left / right power balance, cadence, torque, power phase, torque efficiency, and pedal smoothness.

[0112] In one implementation, the computing device, battery, local storage and transmitter are arranged on a PCB disposed within the structural housing. Thus, the power meter 100 can be constructed efficiently by reducing the number of individual electronic components. In the magnetometer variant of the chain speed sensor 140, the magnetometer 142 and magnet can also be included on the PCB.

[0113] In another implementation, the computing device is configured to calculate tension in the chain, or torque about a rotational axle of a chain-driven vehicle, by sampling strain gauge data and converting the strain gauge data to tension or torque data based on a conversion function. In one implementation, the conversion function represents the physical system of the chain and the set of strain gauges 130 including: the geometry of the chain channel 110 and, therefore, the angle of the chain translating over the convex deviation 116; and the material characteristics of the convex side 122 of the structural housing the force-sensitive flange 128. In another implementation, the conversion function represents the structural dynamics of theBKON-M01-PCTsensing bracket 120 and thereby correlates strain detected at the location of the set of strain gauges 130 on the sensing bracket 120 with the tension of the chain translating through the chain channel 110. Additionally, the conversion function can include calibration parameters, which may be set by a user during a calibration protocol. In another implementation, the conversion function is a lookup table derived from a calibration protocol or set prior to delivery to a user.

[0114] In yet another implementation, the computing device is configured to calculate tension or torque data via an empirical function correlating the strain data from strain gauge 130 with the tension of the chain and / or torque about an axle of the chain driven vehicle. The computing device can execute an empirical function including, but not limited to, linear regression, polynomial regression, support vector machines, or other machine learning algorithms, to estimate the tension or torque based on the measured strain.

[0115] Generally, upon calculating the tension of the chain and / or the torque applied about an axle of the chain driven vehicle, the computing device can calculate the power transmitted through the chain. More specifically, the computing device can calculate the power transmitted by the chain, by multiplying the chain tension data by contemporaneous chain speed data.

[0116] However, one of skill in the art will recognize that the computing device can execute instructions to empirically calculate tension in the chain based on the strain applied by the chain to the sensing bracket 120 based on the tendency of the chain to deflect the sensing bracket 120 when under tension. Thus, the computing device can execute any method for calculating chain tension data based on strain detected by the strain gauge 130.

Claims

BKON-MOl-PCTCLAIMSWe Claim:

1. A power meter comprising:• a chain channel:o characterized by a channel path defining■ a chain inlet;■ a convex deviation; and■ a chain outlet;o comprising a pair of vertically opposing ridges extending along the channel path, each vertically opposing ridge in the pair of vertically opposing ridges characterized by a ridge width less than an inner width of a bicycle chain; and o characterized by a channel height between the pair of vertically opposing ridges greater than or equal to a roller diameter of the bicycle chain;• a sensing bracket:o spanning the pair of vertically opposing ridges; ando configured to measurably deflect in response to a force applied by the bicycle chain to the pair of vertically opposing ridges;• a strain gauge configured to measure deflection of the sensing bracket; and• a chain speed sensor configured to measure a speed of the bicycle chain translating through the chain channel.

2. The power meter of Claim 1, further comprising a retention assembly coupled to the structural housing and configured to substantially maintain a position of the chain channel and the sensing bracket in a direction of translation of the bicycle chain.

3. The power meter of Claim 2, wherein the retention assembly is configured to transiently couple to a front derailleur of a bicycle at a distal end of the retention assembly.

4. The power meter of Claim 2, wherein the retention assembly is configured to transiently couple to a bicycle frame.BKON-MOl-PCT5. The power meter of Claim 1, further comprising a computing device configured to sample the strain gauge and the chain speed sensor to calculate a power transmitted via the bicycle chain translating through the chain channel.

6. The power meter of Claim 1, wherein:• the sensing bracket defines the chain channel; and• the pair of vertically opposing ridges extend from a pair of vertically opposing flanges of the sensing bracket.

7. The power meter of Claim 1, wherein the speed sensor comprises a chain roller configured to rotate in response to translation of the bicycle chain through the chain channel.

8. The power meter of Claim 7, wherein teeth of the chain roller comprise a flexible material configured to laterally deflect in response to insertion of the bicycle chain within the chain channel.

9. The power meter of Claim 1, wherein the speed sensor comprises an optical sensor.

10. The power meter of Claim 1, wherein the speed sensor comprises a Hall effect sensor.

11. The power meter of Claim 1, further comprising an internal chain guide arranged within the chain channel and configured to prevent internal lateral dislocation of the bicycle chain within the chain channel.

12. The power meter of Claim 1, further comprising an external chain guide configured to transiently traverse the chain channel and configured to prevent external lateral dislocation of the bicycle chain out of the chain channel.BKON-MOl-PCT13. The power meter of Claim 1, wherein the convex deviation defines a sagitta greater than or equal to 0.5 millimeters.

14. The power meter of Claim 13, wherein the convex deviation defines a flat surface characterized by a length greater than 12.7 millimeters.

15. A power meter comprising:• a chain channel:o characterized by a channel path defining■ a chain inlet;■ a convex deviation; and■ a chain outlet;o comprising a pair of vertically opposing ridges extending along the channel path, each vertically opposing ridge in the pair of vertically opposing ridges characterized by a ridge width less than an inner width of a roller chain; o characterized by a channel height between the pair of vertically opposing ridges greater than or equal to a roller diameter of the roller chain;• a sensing bracket:o spanning the pair of vertically opposing ridges; ando configured to measurably deflect in response to a force applied by the roller chain to the pair of vertically opposing ridges;• a strain gauge configured to measure deflection of the sensing bracket;• a chain speed sensor configured to measure a speed of the roller chain translating through the chain channel.

16. The power meter of Claim 15, further comprising a computing device configured to sample the strain gauge and the chain speed sensor to calculate a power transmitted via the roller chain translating through the chain channel.

17. The power meter of Claim 15, wherein:BKON-MOl-PCT• the sensing bracket defines the chain channel; and• the pair of vertically opposing ridges extend from a pair of vertically opposing flanges of the sensing bracket.

18. The power meter of Claim 15, wherein the speed sensor comprises a chain roller configured to rotate in response to translation of the roller chain through the chain channel.

19. The power meter of Claim 15, wherein the speed sensor comprises an optical sensor.

20. The power meter of Claim 15, wherein the speed sensor comprises a Hall effect sensor.

21. The power meter of Claim 15, wherein the convex deviation defines a flat surface vertically offset from the chain inlet.

22. The power meter of Claim 21, wherein the flat surface defines a length greater than a pitch of the roller chain.

23. A chain tensiometer comprising:• a chain channel:o characterized by a channel path defining■ a chain inlet;■ a convex deviation; and■ a chain outlet;o comprising a pair of vertically opposing ridges extending along the channel path, each vertically opposing ridge in the pair of vertically opposing ridges characterized by a ridge width less than an inner width of a roller chain; o characterized by a channel height between the pair of vertically opposing ridges greater than or equal to a roller diameter of the roller chain;• a sensing bracket:BKON-MOl-PCTo spanning the pair of vertically opposing ridges; ando configured to measurably deflect in response to a force applied by the roller chain to the pair of vertically opposing ridges; and• a strain gauge configured to measure deflection of the sensing bracket.

24. The chain tensiometer of Claim 23, further comprising a computing device configured to sample the strain gauge to calculate a chain tension of the roller chain translating through the chain channel.

25. The chain tensiometer of Claim 23, wherein:• the sensing bracket defines the chain channel; and• the pair of vertically opposing ridges extend from a pair of vertically opposing flanges of the sensing bracket.

26. The chain tensiometer of Claim 23, wherein the convex deviation defines a flat surface vertically offset from the chain inlet.

27. The chain tensiometer of Claim 26, wherein the flat surface defines a length greater than a pitch of the roller chain.

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