Method and system for determining a travel time in a leading position, particularly in the wind, of a cyclist during group cycling trips

Abstract

The invention relates to a method and a system for determining the riding time of a cyclist in the front position during group cycling rides. The method uses data processing units, each with one transmitting unit and three receiving units, mounted on the bicycles. Using the triangulation method, the relative position of the bicycles is determined based on the propagation time differences of a transmitted radio wave received by the receiving units. This enables the precise determination of when a cyclist is in the front, exposed to the wind position. The goal is to ensure a fair distribution of lead time by measuring how long each cyclist in the group rides in this more strenuous position.

Description

Technical area

[0001] The invention relates to a method for determining a cyclist's travel time in a leading position, particularly in wind conditions, during group cycling trips. A first bicycle is set in motion by a first person, and a second bicycle is set in motion by a second person, in the same direction. A first data processing unit is assigned to the first bicycle, and a second data processing unit is assigned to the second bicycle. The data processing units each comprise one transmitting unit and three receiving units, the positions of the three receiving units being known with respect to a reference point. The method determines the travel time in a leading position, particularly using triangulation.

[0002] Furthermore, the invention relates to a system for determining a travel time in the front position of a cyclist during group bicycle rides. Description

[0003] Cycling in groups offers significant aerodynamic advantages, as cyclists can save up to 30% energy by slipstreaming their teammates. This makes the strategy of changing leads (also known as "rotational riding") a crucial factor for group efficiency and speed. Distributing lead time evenly ensures that no cyclist is disproportionately exposed to wind resistance, which can lead to fatigue and ultimately a slower group pace.

[0004] Ideally, the group would rotate so frequently that each cyclist spends the same amount of time leading into the wind. However, it is currently not possible to accurately break down or record how long each cyclist spends leading into the wind. State of the art

[0005] A device for analyzing an athlete's air resistance is known from DE 10 2018 213 035 B4. The device comprises a signal processing unit configured to receive pressure sensor signals from at least one pressure sensor arranged on an athlete or a sports device. These pressure sensor signals are subsequently processed by the device to analyze the air resistance. This allows an optimal distance between an athlete using the device and a formation of athletes moving in front of them to be determined, thus maximizing the slipstream effect.

[0006] However, this device does not make it easy to determine who in a group rode what proportion of the way into the wind.

[0007] The publication DE 10 2017 206 569 B3 relates to a control method for slipstreaming a two-wheeler, in particular a two-wheeler with a combination of pedals and a motor. In a first step, a pedal stroke is recorded. In a second step, the longitudinal distance of the two-wheeler from the vehicle in front is recorded, and in a third step, the lateral offset of the two-wheeler from the vehicle in front is recorded. Finally, in a fourth step, the motor torque of the drive motor is controlled as a function of the longitudinal distance, the lateral offset, and the pedal stroke. The control of the motor torque is designed to steer the two-wheeler into the slipstream of the vehicle in front or to keep the two-wheeler in the slipstream of the vehicle in front. This reduces the energy required by the drive motor and saves energy from a battery on the two-wheeler used to power the drive motor.The regulation also makes it unlikely that the two-wheeler will collide with the vehicle in front.

[0008] However, such a control method also fails to determine the proportion of travel time in the wind within a group trip. Furthermore, the disclosed control method uses expensive sensors, such as an ultrasonic sensor, a radar sensor, a stereo camera, and / or a LIDAR sensor.

[0009] WO 2021 / 071364 A1 discloses a system for detecting, monitoring, and sanctioning illegal drafting in cycling races, particularly triathlons, based on a combination of radio communication (e.g., UWB, Bluetooth, LoRa), GPS, and optionally optical sensors. It describes various embodiments of proximity monitors that are attached to bicycles and determine the distance and relative position between riders in real time, automatically detect violations of drafting rules, trigger visual or acoustic warnings, and transmit this information to referee devices or central systems for further evaluation and penalty allocation. The system also includes methods for the immediate display and monitoring of penalty times during the race, including geo-fencing and display units along the track.

[0010] DE 10 2014 101 845 A1 discloses a system for the coordinated propulsion of single-track vehicles, in which a "master" vehicle sets a target speed and other vehicles ("slaves") automatically adjust their propulsion power. The goal is synchronized driving in groups, e.g., with e-bikes, despite varying rider performance. This is achieved via wireless communication and, optionally, using distance sensors and automatic braking control. Disclosure of the invention

[0011] The object of the invention was therefore to eliminate the disadvantages of the prior art and in particular to provide a simple and cost-effective, yet accurate method and system for determining a travel time in the front position, especially in the wind, of a cyclist during group bicycle rides.

[0012] The object of the invention is achieved by the features of the independent claims. Advantageous embodiments of the invention are described in the dependent claims.

[0013] In a preferred embodiment, the invention relates to a method for determining a travel time in the front position, in particular in the wind, of a cyclist during group bicycle rides, - wherein a first bicycle is set in motion by a first person and a second bicycle is set in motion by a second person in the same direction of movement; - wherein the first bicycle is assigned a first data processing unit and the second bicycle is assigned a second data processing unit, each comprising one transmitting unit and three receiving units, wherein the positions of the respective three receiving units are known with respect to a reference point; comprising the following method steps: - the transmitting unit of the first data processing unit transmits a radio wave which is detected by the three receiving units of the second data processing unit; - the second data processing unit determines the propagation time differences of the radio wave to the various receiving units; - the second data processing unit uses the propagation time differences to determine a distance difference between the respective receiving units of the second data processing unit and the transmitting unit of the first data processing unit; - based on the determined distance differences between the respective receiving units of the second data processing unit and the transmitting unit of the first data processing unit, the second data processing unit uses the triangulation method to determine a position of the transmitting unit of the first data processing unit, whereby the relative positions of the first and second data processing units to one another can be determined; - if the position of the second data processing unit is in front of the position of the first data processing unit with respect to a direction of movement, a time is recorded and / or a value is added; if the position of the second data processing unit is behind the position of the first data processing unit with respect to a direction of movement, no time is recorded and / or an already recorded time is stopped and / or a value is subtracted and / or no value is added.

[0014] One advantage of the proposed method is that it provides an accurate and reliable method for determining a cyclist's travel time in the lead position, especially against the wind, during group cycling rides. By using data processing units and triangulation, the relative position of the bicycles can be accurately determined, allowing the lead cyclist's travel time to be measured. This can be used, for example, to optimize training or racing strategies.

[0015] For the purposes of the invention, a group cycling ride is a type of cycling in which several cyclists ride together on a route, particularly in the same direction. This form of cycling is often used as a training session or as a recreational activity. A group cycling ride can consist of two or more cyclists. During a group cycling ride, cyclists can take turns riding in a leading position to reduce wind resistance for the other cyclists.

[0016] The front position, especially in the wind, is the preferred position within a group bike ride where the cyclist is most exposed to air resistance. The front position is also referred to as the leading position or the "wind edge". The front position does not necessarily have to be the first position in a direction of movement. In a large group or a large field of cyclists, it can also be positions behind the first position. These positions can ride laterally offset from the cyclist in the first position and also be exposed to the wind. If several cyclists are riding in a group, the wind resistance for the cyclists following behind can be reduced by lining up in a line behind one another and the lead cyclist blocking the wind for the others. If a cyclist rides in the front position, however, they have to fight against the full wind resistance.This position therefore requires greater physical effort and requires greater performance than the positions in the middle or rear of the group. Cyclists typically alternate between the front positions to share the load and maintain the group's speed. The method according to the invention serves to achieve an even load among the cyclists.

[0017] In a group bike ride, at least one bicycle is set in motion by a first person, and a second bicycle is set in motion by a second person, traveling in the same direction. A bicycle is typically set in motion by the rider's pedaling movements. The rider pedals, and the bicycle is propelled by the conversion of muscle power into kinetic energy.

[0018] A common direction of movement preferably means that both objects (in this case, the two bicycles) are moving in the same direction. This means that, considering the movement of the bicycles, they are essentially moving parallel to each other in the same direction. If the directions of movement of the two bicycles were different, they would either move away from each other or towards each other and thus no longer travel in a group.

[0019] A data processing unit is preferably an electronic unit that serves to acquire, process, and transmit data. A data processing unit preferably comprises various components, such as a microcontroller, a processor, a memory, various sensors, actuators, and communication devices. For the purposes of the invention, two data processing units are preferably provided, wherein a first data processing unit is assigned to a first bicycle and a second data processing unit is assigned to a second bicycle. Assignment can mean, for example, that the data processing unit is mounted on the bicycles or is carried by the people who set the bicycles in motion. Particularly preferably, a data processing unit further comprises a transmitting unit and at least three receiving units.

[0020] In a preferred embodiment, the transmitting unit emits a radio wave that is detected by the receiving units. The transmitting unit preferably comprises a transmitter and an antenna that work together to transmit the radio signal. The transmitter can use different frequencies and transmission methods depending on the requirements of the specific application. In this case, the signal will preferably be in the GHz range, which means it is a wireless high-frequency communication.

[0021] Furthermore, a receiving unit preferably comprises an antenna that receives the radio signal and a receiver that amplifies and demodulates the signal. The receiving units of a data processing unit are preferably arranged such that their relative positions to one another and their (absolute) positions with respect to a reference point are known. This allows the data processing unit to measure the propagation time differences of a radio signal to the various receiving units.

[0022] In a further preferred embodiment, the data processing unit comprises a housing. Within this housing, the receiving units and the transmitting unit are arranged at known positions relative to a reference, in particular a reference point, within the housing. This allows the distances and relative positions of the receiving units to each other and to the reference point to be determined and are thus known. Particularly preferably, the reference point within the housing is the origin of a virtual coordinate system, which serves as the basis for determining a distance between a first and second data processing unit.

[0023] A radio wave is preferably an electromagnetic wave used to transmit information through air or free space. Radio waves have a specific frequency and wavelength and can be transmitted and received by antennas. For the proposed method, radio waves with a frequency of 1 kHz to 30 GHz are preferably used. Frequencies in the range of 1-10 GHz are particularly preferred, as they offer sufficient range and accuracy. Radio waves can be selected from, for example, Bluetooth, UWB, Wi-Fi, Zigbee, RFID, radio waves (FM, AM), radar waves, or ultrasonic waves.

[0024] The method according to the invention preferably uses the "Time Difference of Arrival" (TDOA) method for determining position based on propagation time differences. With TDOA, the propagation time differences are preferably measured between multiple receivers and a single signal source. Based on the propagation time differences, a difference in the distances of the respective receiving units from the signal source can be determined. The propagation time differences can be measured either directly or indirectly calculated by comparing the signal propagation time between the receivers. The difference in the distances is determined by multiplying the propagation time difference by the propagation speed.

[0025] Triangulation enables precise positioning and is a fundamental method in cartography and location determination. At least two known points and one unknown point are used to calculate its position. The calculations are based on the principles of trigonometry, allowing precise spatial coordinates to be determined. In this case, the coordinates of the three receiving units in the respective data processing units are known, while the transmitting unit of the respective other data processing unit is unknown. The preferred application of triangulation in the context of the present invention is described with reference to Fig. 4 explained below.

[0026] In the context of the proposed method, the terms "time" and "value" refer to mechanisms for measuring and evaluating the contributions of cyclists in a group ride. "Time" preferably represents the duration a cyclist spends in the lead position against the wind, with this time being recorded to document the energy expenditure and performance in this demanding position. If the cyclist is released from the lead, this time measurement is stopped to precisely record the time in the lead. In parallel or alternatively, the "value" can be viewed as a type of points system that is added up or subtracted in certain situations based on position and the leadership effort assumed. This system makes it possible, for example, to evaluate the efficiency and fairness of the contributions of all cyclists within the group in addition to pure time measurement.

[0027] In a preferred embodiment, the radio wave is transmitted at predefined time intervals to enable continuous or periodic updates of the cyclists' relative positions. This allows for continuous monitoring of the positions, which can lead to timely and dynamic adjustment of the riding strategy or can also be used for subsequent analyses and training evaluations.

[0028] In a preferred embodiment, visual, acoustic, or haptic feedback regarding a relative position and / or travel time in the leading position is provided to the cyclists. Visual, acoustic, or haptic feedback regarding the relative position and travel time helps cyclists recognize and correct their position within the group. This feedback can increase the cyclists' motivation by providing them with immediate feedback regarding their performance and contribution to the group effort. It is understood that the data processing unit has provided appropriate means for this purpose, such as a display, an LED indicator, a loudspeaker, headphone interfaces, or vibration motors.

[0029] In another preferred embodiment, the collected data is wirelessly transmitted to an external device, such as a smartphone or computer, to enable detailed analysis and visualization. The wireless transmission of collected data to an external device enables comprehensive analysis and long-term monitoring of training and competition performance. The ability to perform detailed analysis and visualization of the data on external devices can contribute to improving training efficiency and strategic planning.

[0030] Determined data refers, in particular, to the recorded time or the recorded values. However, other recorded sensor data can also be understood as determined data. Furthermore, it can also refer to data resulting from calculations, where the recorded time and / or the recorded values, as well as other recorded sensor data, serve as the basis for these calculations.

[0031] In another preferred embodiment, additional sensors such as GPS, accelerometers, or gyroscopes are integrated into the data processing units to further refine the positioning. The integration of additional sensors such as GPS, accelerometers, or gyroscopes improves the accuracy of positioning, particularly under difficult environmental conditions or in the presence of signal interference. The combination of various sensor data enables a more comprehensive analysis of driving performance.

[0032] In a further preferred embodiment, the determined travel time in the front position is used to calculate an efficiency index or for comparative analysis with previous journeys.

[0033] In this context, the efficiency index is preferably a metric for assessing the efficiency and fairness of lead time within a group of cyclists. The index preferably sets the duration each cyclist spends in the front position, especially in the wind, in relation to each other and to the total ride time of the group. This not only allows for the quantification of individual contributions to the lead task, but also for the evaluation of aerodynamic efficiency and the resulting energy savings for the entire team.

[0034] The efficiency index can be composed, for example, as follows: t¯Leading time=TTotal travel timen n≥2 t̅ Führungszeit: Average (target) lead time in the wind of a cyclist (mean) n: Number of cyclists within group T Gesamtfahrtzeit : Total travel time of the group

[0035] For an even distribution of the lead time and optimal efficiency within the group cycling trip, each cyclist should have the mean t̅ Führungszeit drive in the front position. By determining the variance, the efficiency index can now be calculated EIndex=∑i=1i=n(t¯leadership time−ti leadership time)2nTTotal travel time t i Führungszeit : recorded leading time of a single driver

[0036] The lower the value of the efficiency index E Index is, the more evenly the distribution of lead times among the cyclists is, which indicates a higher efficiency of the group ride. An E Indexclose to zero indicates that all riders have taken on approximately equal shares of the leading work, which allows for optimal use of the aerodynamic advantages of slipstreaming.

[0037] The use of an efficiency index makes it possible to evaluate the effectiveness or efficiency of a group. Comparative analysis with previous rides can identify trends and patterns in riding behavior, which can help optimize training sessions and competition strategies.

[0038] In a further preferred embodiment, the time measurement or the value calculation is controlled adaptively based on the relative positions, for example by adapting to the group size or the changing wind conditions.

[0039] Adaptive control of timing and value calculation enables more precise and meaningful data acquisition, taking into account the variable conditions of a group ride. By adapting timing and value calculation to, for example, group size and / or changing wind conditions, the system can account for various influences. In particularly strong headwinds and / or particularly high speeds, riding in the front position can be given greater weight than riding in the front position in light headwinds or at low speeds. The size of the group also influences the amount of time spent in the slipstream in the rear position, so that the fact that the riders are more rested when they take the lead can be taken into account.In addition, the rider's performance can also be factored into the weighting, allowing elite athletes to be weighted differently than recreational riders, and even distinguishing between men and women. The flexibility of the system increases its applicability in different riding situations and makes it a valuable tool for cyclists and coaches who train under different conditions.

[0040] In a further preferred embodiment, the method is characterized in that a first pressure sensor is assigned to the first bicycle and a second pressure sensor is assigned to the second bicycle, and the pressure sensors are used to measure the air pressure in the immediate vicinity of the bicycles. Assigning pressure sensors to the bicycles enables the measurement of the air pressure in the immediate vicinity, which is important for the analysis of aerodynamic conditions. Detecting the air pressure can contribute to a more accurate calculation of the air resistance acting on the cyclists and thus enable a more detailed performance analysis. The pressure data can also be used to calibrate other sensors or systems to improve the accuracy of the overall data acquisition.

[0041] In another preferred embodiment, the measured pressure is used to weight the recorded time or the added value. Using the measured pressure to weight the recorded time or the added value allows for finer tuning of the performance measurement. Taking air pressure into account when measuring time can lead to a fairer assessment of the cyclist's performance.

[0042] In a further preferred embodiment, the invention relates to a system for determining a travel time in the front position, in particular in the wind, of a cyclist during group bicycle rides, comprising: - a first bicycle and a second bicycle which can be set in motion by a first person and a second person respectively in the same direction of movement; - a first data processing unit associated with the first bicycle and a second data processing unit associated with the second bicycle, each data processing unit comprising one transmitting unit and three receiving units, and the positions of the respective three receiving units relative to a reference point are known; - means for determining propagation time differences of a radio wave emitted by the transmitting unit of the first data processing unit to the various receiving units of the second data processing unit; - means for determining distance differences between the respective receiving units of the second data processing unit and the transmitting unit of the first data processing unit via the propagation time differences; - means for determining the position of the transmitting unit of the first data processing unit by triangulation based on the determined distance differences, whereby the relative positions of the first and second data processing units to one another can be determined; - Means for recording a time when the position of the second data processing unit is ahead of the position of the first data processing unit with respect to a direction of movement, and for stopping or not recording the time when the position of the second data processing unit is behind the position of the first data processing unit with respect to a direction of movement.

[0043] The system enables precise determination of the riding time in the leading position, which is important for analyzing lead performance and slipstreaming in group rides. Triangulation to determine the relative positions of the data processing units ensures high accuracy in position detection.

[0044] A person skilled in the art will recognize that the advantages, technical effects and preferred embodiments discussed in connection with the method according to the invention apply analogously to the system according to the invention for determining a travel time in the front position, in particular in the wind, of a cyclist during group bicycle rides.

[0045] Further embodiments are explained in more detail below with reference to the accompanying drawings. The composite floor panel according to the invention is not intended to be limited solely to these listed embodiments. Rather, embodiments are also envisaged that are now and in the future equally accessible to the skilled person using other technical means. Short description of the drawing Fig. 1 shows a schematic representation of a group bicycle ride, in which the method according to the invention is used Fig. 2 shows the method step of transmitting a radio wave from the transmitting unit of the first data processing unit, wherein the radio wave is detected by the receiving units of the second data processing unit at three different times Fig. 3 shows the method step of transmitting a radio wave from the transmitting unit of the first data processing unit, Fig. 4 demonstrates the use of the triangulation method in the preferred method Preferred embodiments

[0046] Fig. Figure 1 illustrates, in abstract form, a group bicycle ride, wherein a preferred embodiment of the method according to the invention is used. The illustrated group consists of two cyclists. A first bicycle 1 is set in motion by a first person 5, and a second bicycle 3 is set in motion by a second person 7 in the same direction of movement 17. Data processing units 9, 11 are assigned to each of the bicycles 1, 3 (these are not shown in the figure). Fig. 1), each comprising a transmitting unit 13 and three receiving units 15.

[0047] In the course of the proposed method, a radio wave 19 is transmitted from the transmitting unit 13 of a first data processing unit 9, which can be detected by the three receiving units 15 of a second data processing unit 11. Based on determined propagation time differences and the application of the triangulation method, the relative position of the first and second data processing units 9, 11 to each other can be determined.

[0048] Fig. Figure 2 schematically shows two data processing units 9, 11, each associated with a bicycle 1, 3. These are set in motion by a first and second person 5, 7 according to a same direction of movement 17.

[0049] Both the first and the second data processing units 9, 11 preferably comprise a housing 25, a transmitting unit 13 and three receiving units 15. Furthermore, a reference point 23 is preferably provided in the housing 25, which acts as the origin for a (virtual) coordinate system.

[0050] The transmitting unit 13 of the first data processing unit 9 emits a radio wave 19. This is detected at time t1 by a first receiving unit 15, at time t2 by a second receiving unit 15, and at time t3 by a third receiving unit 15. By detecting the times of the radio wave 19 at the individual receiving units 15, the propagation time differences (Δt 13 , 8t 12 , Δt 23 ) can be determined. Thus: Δt13=t1−t3 Δt12=t1−t2 Δt23=t2−t3

[0051] Fig. 3 shows schematically the distance differences (Δd 13 , Δd 12, Δd 23 ), which is calculated using the runtime differences (Δt 13 , Δt 12 , Δt 23 ) can be determined. The individual components of the data processing units 9, 11 are already in Fig. 2 has been discussed.

[0052] Based on the propagation speed of the radio wave in air (c Luft ) the individual distance differences are calculated as follows: Δt13×cAir=Δd13 Δt12×cAir=Δd12 Δt23×cAir=Δd23

[0053] Fig.Figure 4 demonstrates the use of the triangulation method in the preferred method. It is assumed that the position of the transmitting unit 13 of a first data processing unit 9 corresponds to an intersection point formed by the three circles drawn around the three receiving units 15 of a second data processing unit 11. The radius of the circles corresponds to the distance d1, d2, and d3 of the three receiving units 15 of the second data processing unit 11 from the transmitting unit 13 of the first data processing unit 9.

[0054] The distance between two points in three-dimensional space can generally be calculated using the Pythagorean theorem: d1=(x1−x)2+(y1−y)2+(z1−z)2 d2=(x2−x)2+(y2−y)2+(z2−z)2 d3=(x3−x)2+(y3−y)2+(z3−z)2

[0055] Here, x, y, and z represent the coordinates of the special unit 13 of the first data processing unit 9, whereas (x1, y1, z1), (x2, y2, z2) and (x3, y3, z3) correspond to the coordinates of the three receiving units 15 of the second data processing unit 11, which are known as already discussed.

[0056] Using the previously determined distance differences Δd 13 , Δd 12 , and Δd 23 and the known positions of the receiving units 15 of the second data processing unit 11, the position of the transmitting unit 13 of the first data processing unit 9 can be determined by solving a system of non-linear equations: Δd13=(x1−x)2+(y1−y)2+(z1−z)2−(x3−x)2+(y3−y)2+(z3−z)2=Δt13×cAir Δd12=(x1−x)2+(y1−y)2+(z1−z)2−(x2−x)2+(y2−y)2+(z2−z)2=Δt12×cAir Δd23=(x2−x)2+(y2−y)2+(z2−z)2−(x3−x)2+(y3−y)2+(z3−z)2=Δt23×cAir

[0057] The position or coordinates (x, y, z) of the transmitting unit 13 of the first data processing unit 9 obtained by solving the non-linear equations refer to the reference point 23 of the second data processing unit 11 (or the coordinate system derived therefrom).

[0058] It is understood that it can be determined from this whether the first data processing unit 9 or the first bicycle 1 is located in front of or behind the second data processing unit 11 or the second bicycle 3 in the direction of movement 17. LIST OF REFERENCE SYMBOLS 1 First bicycle 3 Second bicycle 5 First Person 7 Second Person 9 First data processing unit 11 Second data processing unit 13 Transmitter unit 15 Receiving unit 17 Direction of movement 19 radio wave 21 System 23 Reference point inside the housing 25 housings d1 Distance between a first receiving unit of the second data processing unit and a transmitting unit of the first data processing unit d2 Distance between a second receiving unit of the second data processing unit and a transmitting unit of the first data processing unit d3 Distance between a third receiving unit of the second data processing unit and a transmitting unit of the first data processing unit Δd 13 Distance difference d1 - d3 Δd 12 Distance difference d1 - d2 Δd 23 Distance difference d2 - d3

Claims

[1] Method for determining a travel time in the front position, in particular in the wind, of a cyclist during group bicycle rides, wherein a first bicycle (1) is set in motion by a first person (5) and a second bicycle (3) is set in motion by a second person (7) in the same direction of movement; wherein the first bicycle (1) is assigned a first data processing unit (9) and the second bicycle (3) is assigned a second data processing unit (11), each comprising a transmitting unit (13) and three receiving units (15), the positions of the respective three receiving units (15) being known with respect to a reference point (23); comprising the following procedural steps: - the transmitting unit (13) of the first data processing unit (9) transmits a radio wave (19) which is detected by the three receiving units (15) of the second data processing unit (11); - the second data processing unit (11) determines propagation time differences of the radio wave (19) to the various receiving units (15); - the second data processing unit (11) determines a distance difference (Δd 12 , Δd 23 , Δd 13 ) of the respective receiving units (15) of the second data processing unit (11) to the transmitting unit (13) of the first data processing unit (9); - based on the determined distance differences (Δd 12 , Δd 23 , Δd 13) between the respective receiving units (15) of the second data processing unit (11) and the transmitting unit (13) of the first data processing unit (9), a position of the transmitting unit (13) of the first data processing unit (9) is determined by the second data processing unit (11) using the triangulation method, whereby the relative positions of the first and second data processing units (9, 11) to one another can be determined; - If the position of the second data processing unit (11) is in front of the position of the first data processing unit (9) with respect to a direction of movement (17), a time is recorded and / or a value is added; if the position of the second data processing unit (11) is behind the position of the first data processing unit (9) with respect to a direction of movement (17), no time is recorded and / or an already recorded time is stopped and / or a value is subtracted and / or no value is added. [2] Method according to claim 1, wherein the radio wave (19) is transmitted at predefined time intervals to enable continuous or periodic updates of the relative positions. [3] Method according to one of the preceding claims, wherein a visual, acoustic or haptic feedback about a relative position and / or travel time in the front position is given to the cyclists (5, 7). [4] Method according to one of the preceding claims, wherein determined data are transmitted wirelessly to an external device, such as a smartphone or a computer, in order to enable detailed evaluation and visualization. [5] Method according to one of the preceding claims, wherein additional sensors such as GPS, accelerometers or gyroscopes are integrated into the data processing units (9, 11) to further refine the position determination. [6] Method according to one of the preceding claims, wherein the determined travel time in the front position is used to calculate an efficiency index or for comparative analysis with previous journeys. [7] Method according to one of the preceding claims, wherein the time measurement or value calculation is controlled adaptively on the basis of the relative positions, for example by adapting to the group size or the changing wind conditions. [8] Method according to one of the preceding claims, wherein a first pressure sensor is assigned to the first bicycle (1) and a second pressure sensor is assigned to the second bicycle (3), and the pressure sensors are used to measure the air pressure in the immediate vicinity of the bicycles (1, 3). [9] Method according to claim 8, wherein the measured pressure is used for weighting the recorded time or the added value, [10] System for determining a travel time in the front position, in particular in the wind, of a cyclist during group cycling trips, comprising: - a first bicycle (1) and a second bicycle (3) which can be set in motion in the same direction of movement by a first person (5) and a second person (7) respectively; - a first data processing unit (9) associated with the first bicycle and a second data processing unit (11) associated with the second bicycle, each data processing unit (9, 11) comprising one transmitting unit (13) and three receiving units (15), and the positions of the respective three receiving units relative to a reference point (23) are known; - means for determining propagation time differences of a radio wave (19) emitted by the transmitting unit (13) of the first data processing unit (9) to the various receiving units (15) of the second data processing unit (11); - Means for determining distance differences (Δd 12 , Δd 23 , Δd 13 ) the respective receiving units (15) of the second data processing unit (11) to the transmitting unit (13) of the first data processing unit (9) via the propagation time differences; - means for determining the position of the transmitting unit (13) of the first data processing unit (9) by triangulation based on the determined distance differences (Δd 12 , Δd 23 , Δd 13 ), whereby the relative positions of the first and second data processing units (9, 11) to each other can be determined; - means for recording a time when the position of the second data processing unit (11) is in front of the position of the first data processing unit (9) with respect to a direction of movement (17), and for stopping or not recording the time when the position of the second data processing unit (11) is behind the position of the first data processing unit (9) with respect to a direction of movement (17).

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