USRE48626E1 - Bicycle input force processing apparatus - Google Patents

Abstract

A bicycle crank arm apparatus comprises a crank arm having a crank axle mounting portion and a pedal mounting portion. A circuit-mounting structure is disposed between the crank axle mounting portion and the pedal mounting portion, wherein the circuit-mounting structure is configured to detachably mount a measurement board. When a measurement board is mounted to the circuit-mounting structure, the resulting combination forms a bicycle input force processing apparatus.

Description

BACKGROUND OF THE INVENTION

The present invention is directed to bicycles and, more particularly, to various features of a bicycle input force processing apparatus.

Some bicycle components have sensors attached to them to measure various operating characteristics of the component. For example, transmission shift control devices may have position sensors attached to the operating cable winding mechanism in order to sense the current operating position of the operating cable winding member. The position of the operating cable winding member provides information about the current gear ratio of the bicycle transmission, and that information may be communicated to the rider through a display. In another example, a magnet may be mounted to one of the spokes of the bicycle wheel, and a sensor such as a reed switch may be mounted to the bicycle frame so that the magnet passes by the sensor upon every revolution of the wheel. As a result, the sensor produces an electrical pulse every time the magnet passes by the sensor, and the time between successive pulses may be used to determine the speed of the bicycle. In yet another example, a force sensor such as a strain gauge may be mounted to the surface of a component such as a pedal crank or a wheel hub in order to measure torque being applied to the component. The information from the sensor then may be used to calculate the effort exerted by the rider.

SUMMARY OF THE INVENTION

The present invention is directed to various features of a bicycle input force measuring apparatus. In one embodiment, a bicycle crank arm apparatus comprises a crank arm having a crank axle mounting portion and a pedal mounting portion. A circuit-mounting structure is disposed between the crank axle mounting portion and the pedal mounting portion, wherein the circuit-mounting structure is configured to detachably mount a measurement board. When a measurement board is mounted to the circuit-mounting structure, the resulting combination forms a bicycle input force processing apparatus. Additional inventive features will become apparent from the description below, and such features may be combined with the above features to provide additional benefits.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a bicycle that includes particular embodiments of electrically-controlled bicycle components;

FIG. 2 is a detailed view of particular embodiments of handlebar-mounted components of the bicycle;

FIG. 3 is a schematic view of particular embodiments of crank arms and a crank axle of the bicycle;

FIG. 4 is a schematic view of particular embodiments of measurement boards and a power source mounted to the crank arms and to the crank axle, respectively;

FIG. 5 is a perspective view of a particular embodiment of a measurement board;

FIG. 6 is a perspective view of another embodiment of a measurement board with an attached control and communication circuit;

FIG. 7 is a perspective view of a particular embodiment of a power source;

FIG. 8 is a schematic view of measurement board placement to measure a driving torque;

FIG. 9 is a schematic view of measurement board placement to measure an out-of-plane force;

FIG. 10 is a schematic view of measurement board placement to measure a radial force; and

FIG. 11 is a schematic view of measurement board placement to measure a torsional moment force.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 1 is a side view of a bicycle4 that includes particular embodiments of electrically-controlled components. Bicycle4 is a sport bicycle such as a mountain bicycle, and it comprises aframe8, afront fork12 rotatably mounted toframe8, ahandlebar assembly16 mounted to the upper part offork12, afront wheel20 rotatably attached to the lower part offork12, arear wheel24 rotatably attached to the rear offrame8, afront transmission28, arear transmission32, achain34 operatively coupled tofront transmission28 andrear transmission32, and asaddle38. Afront wheel brake42 is provided for brakingfront wheel20, and arear wheel brake46 is provided for brakingrear wheel24. As shown inFIG. 2,respective grips50a,50b and brake levers54a,54b are provided on both ends ofhandlebar assembly16. Brakelever54a is connected tofront wheel brake42 for brakingfront wheel20, andbrake lever54b is connected torear wheel brake46 for brakingrear wheel24.

Front transmission28 is a mechanical unit attached to the central lower part offrame8 for transmitting drive force generated by the rider torear transmission32 viachain34.Front transmission28 comprises threesprockets58 of various sizes and afront derailleur62. The threesprockets58 are installed on agear crank66 that is rotated when the rider pushespedals70 and72.Gear crank66 comprises acrank axle74 that passes horizontally and rotatably through a bottom bracket offrame8, aright crank arm82, and aleft crank arm86. A first end portion ofright crank arm82 includes an axle-mounting opening82a (FIG. 3) for mountingright crank arm82 tocrank axle74, and a second end portion ofright crank arm82 includes a pedal-mounting opening82b formounting pedal70.Sprockets58 are attached toright crank arm82. A first end portion ofleft crank arm86 includes an axle-mounting opening86a for mountingleft crank arm86 tocrank axle74, and a second end portion ofleft crank arm86 includes a pedal-mounting opening86b formounting pedal72.Front derailleur62 selectively engageschain34 with one of the threesprockets58 and can be moved by a motor (not shown) that is controlled by acontrol unit90 mounted tohandlebar assembly16.

Rear transmission32 transmits the driving force fromchain34 torear wheel24.Rear transmission32 comprises arear sprocket cluster94 and arear derailleur98.Rear sprocket cluster94 comprises a plurality ofsprockets102 mounted concentrically with the hub portion ofrear wheel24. Rearderailleur98 engageschain34 with selected ones ofsprockets102 and can be moved by a motor (not shown) that is controlled bycontrol unit90.

As shown inFIG. 2,control unit90 includes a box-like housing106. Adisplay unit110, apower switch114, and amode switch118 are arranged on the upper surface ofhousing106.Shift command units122a,122b are provided inwardly ofgrips50a,50b and brake levers54a,54b, respectively, andcontrol unit90 is operatively is connected toshift command units122a,122b.Shift command units122a,122b are used for shiftingfront transmission28 andrear transmission32, respectively.Control unit90 is connected tofront transmission28 and torear transmission32 by a connector unit126 (FIG. 1).

As shown inFIG. 3, in this embodiment a circuit-mounting structure having a first circuit-mounting opening82c is formed at a laterallyinner side surface82d ofcrank arm82, and a circuit-mounting structure having a second circuit-mounting opening82e is formed at a laterallyouter side surface82f ofcrank arm82. First circuit-mounting opening82c and second circuit-mounting opening82e includerespective bottom floors82g and82h so that first circuit-mounting opening82c and second circuit-mounting opening82e are formed as recesses in laterallyinner side surface82d and laterallyouter side surface82f, respectively.

As used herein, the inner side means the side of the crank arm that faces the bicycle frame when the crank arm is attached to the bicycle, the outer side means the side of the crank arm that faces away from the bicycle frame, the upper side means the side of the crank arm that faces upwardly when the crank arm is oriented generally horizontally with the outer side of the crank arm facing the viewer and the axle-mounting opening on the left, and the lower side means the side of the crank arm that faces downwardly when the crank arm is oriented generally horizontally with the outer side of the crank arm facing the viewer and the axle-mounting opening on the left.

First circuit-mounting structures130 are disposed within first circuit-mounting opening82c, and second circuit-mounting structures134 are disposed within second circuit-mounting opening82e. First and second circuit-mounting structures130 and134 are configured to detachably mount corresponding measurement boards138 (FIGS. 4 and 5) tocrank arm82 at the respective first and second circuit-mounting openings82c and82e. First and second circuit-mounting structures130 and134 may be formed as continuous, one-piece structures withcrank arm82, or they may be separate structures welded to or otherwise bonded or fastened tocrank arm82. In this embodiment, first and second circuit-mounting structures130 and134 are structured as cylindrical pillars or some other forms of projections or protuberances. Preferably, but not necessarily, first and second circuit-mounting structures130 and134 may include further circuit-mounting openings130a and134a containing further circuit-mounting structures in the form ofthreads130b and134b. In other words, first circuit-mounting structures130 and second circuit-mounting structures may be formed as threaded nuts.

As shown inFIG. 5,measurement board138 may comprise asubstrate142 having atop surface142a and abottom surface142b, asensor146 disposed attop surface142a for measuring an input force, anelectrical connector150 electrically connected tosensor146 throughwiring154, and mountingopenings158 in the form of through holes.Substrate142 may be a printed circuit board or a semiconductor, metal or other conductive or nonconductive rigid or flexible sheet. In this embodiment,sensor146 comprises a strain gauge (e.g., a plurality of resistors configured as a Wheatstone bridge) that may be affixed tosubstrate142 or formed as part ofsubstrate142.Sensor146 may be formed at least in part from a semiconductor material to detect the strain onsubstrate142. Of course, other configurations ofsensor146 andsubstrate142 will be readily understood depending upon the material used.

As shown inFIG. 4, eachmeasurement board138 may be detachably mounted to its corresponding first or second circuit-mounting structures130 or134 using threaded fasteners such asscrews162 that extend throughmounting openings158 insubstrate142 and into their corresponding first or second circuit-mounting structures130 or134. If desired, first and second circuit-mountingopenings82c and82e may have steppedportions82i and82j so thatmeasurement boards138 are disposed within theirrespective mounting openings82c and82e, andbottom surfaces142b ofmeasurement boards138 are flush with their correspondinginner side surface82d andouter side surface82f ofcrank arm82. As shown inFIG. 3,detachable covers166 may cover first and second circuit-mountingopenings82c and82e when ameasurement board138 is not mounted in a corresponding first or second circuit-mountingopening82c or82e. In this embodiment, mountingopenings82c and82e may be sealed by theirrespective measurement boards138.

As shown inFIG. 3, in this embodiment a circuit-mounting structure having a first circuit-mountingopening86c is formed at a laterallyinner side surface86d ofcrank arm86, and a circuit-mounting structure having a second circuit-mountingopening86e is formed at a laterallyouter side surface86f ofcrank arm86. First circuit-mountingopening86c and second circuit-mountingopening86e includerespective bottom floors86g and86h so that first circuit-mountingopening86c and second circuit-mountingopening86e are formed as recesses in laterallyinner side surface86d and laterallyouter side surface86f respectively. First circuit-mountingstructures170 are disposed within first circuit-mountingopening86c, and second circuit-mountingstructures174 are disposed within second circuit-mountingopening86e. First and second circuit-mountingstructures170 and174 may be formed as continuous, one-piece structures withcrank arm86, or they may be separate structures welded to or otherwise bonded or fastened to crankarm86. In this embodiment, as with first and second circuit-mountingstructures130 and134 incrank arm82, first and second circuit-mountingstructures170 and174 are structured as cylindrical pillars or some other forms of projections or protuberances with further circuit-mountingopenings170a and174a containing further circuit-mounting structures in the form ofthreads170b and174b.

As shown inFIG. 4, first circuit-mountingstructures170 are configured to detachably mount a measurement board178 (FIG. 6) to laterallyinner side surface86d ofcrank arm86 at first circuit-mountingopening86c, and second circuit-mountingstructures174 are configured to detachably mount a previously-describedmeasurement board138 to laterallyouter side surface86f ofcrank arm86 at second circuit-mountingopening86e. As shown inFIG. 6,measurement board178 may comprise a substrate182 having atop surface182a and abottom surface182b, asensor186 disposed attop surface182a for measuring an input force, a control andcommunication part190 mounted tobottom surface182b, and mountingopenings194 in the form of through holes. A similar through hole (not shown) that aligns with the right-side mounting opening194 is disposed in control andcommunication part190. Control andcommunication part190 comprises ahousing190a and control andcommunication circuitry192 insidehousing190a.Housing190a may be made of resin to facilitate the transmission of electromagnetic waves therethrough. Control andcommunication part190 may be disposed ontop surface182a of substrate182, in which case substrate182 or crankarm86 may be made of a non-metallic material, or control andcommunication part190 may be disposed onbottom surface182b of substrate182.

As withmeasurement board138, substrate182 may be a printed circuit board or a semiconductor, metal or other conductive or nonconductive rigid or flexible sheet.Sensor186 comprises a strain gauge (e.g., a plurality of resistors configured as a Wheatstone bridge) that may be affixed to substrate182 or formed as part of substrate182.Sensor186 may be formed at least in part from a semiconductor material to detect the strain on substrate182.Sensor186 is operatively coupled to control andcommunication part190 throughwiring198, and anelectrical connector202 is electrically connected to control andcommunication part190 throughwiring206. Wiring198206 pass through a through-hole193 in substrate182.

Control andcommunication circuitry192 may include a microprocessor programmed to calculate force or power applied to crankarms82 and86 in a well-known manner based on the signals received fromsensors146 and186. Control andcommunication circuitry192 also includes atransmitter192a to transmit sensor signals and/or calculated data wirelessly to controlunit90.

As shown inFIG. 4,measurement board178 may be detachably mounted to first circuit-mountingstructures170 using threaded fasteners such asscrews162 that extend through mountingopenings194 in substrate182 (as well as through the aligned opening in control and communication part190) and into first circuit-mountingstructures170, andmeasurement board138 may be detachably mounted to second circuit-mountingstructures174 using threaded fasteners such asscrews162 that extend through mountingopenings158 insubstrate142 and into second circuit-mountingstructures174. If desired, first and second circuit-mountingopenings86c and86e may have respective steppedportions86i and86j so thatmeasurement boards178 and138 are disposed within theirrespective mounting openings86c and86e, and the bottom surfaces182b and142b ofrespective measurement boards178 and138 are flush with their correspondinginner side surface86d andouter side surface86f ofcrank arm86. As shown inFIG. 3,detachable covers166 may cover first and second circuit-mountingopenings86c and86e when ameasurement board178 or138 is not mounted at its corresponding first or second circuit-mountingopening86c or86e.

As shown inFIGS. 3 and 4, afirst wiring harness210 is disposed at least partially within ahollow chamber214 incrank arm82, and asecond wiring harness218 is disposed at least partially within ahollow chamber222 incrank arm86.First wiring harness210 comprises awiring bundle226, a firstelectrical connector230, a secondelectrical connector234, and a thirdelectrical connector238. In this embodiment, firstelectrical connector230 is rigidly mounted tobottom floor82g of first circuit-mountingopening82c so as to be exposed to first circuit-mountingopening82c, and secondelectrical connector234 is rigidly mounted tobottom floor82h of second circuit-mountingopening82e so as to be exposed to second circuit-mountingopening82e.Electrical connector150 ofmeasurement board138 at first circuit-mountingopening82c is connected to firstelectrical connector230, andelectrical connector150 ofmeasurement board138 at second circuit-mountingopening82e is connected to secondelectrical connector234. If desired, firstelectrical connector230 and secondelectrical connector234 may form first and second circuit-mounting structures alone or in combination with their respective first and second circuit-mountingstructures130 and134, especially if one or both of theelectrical connectors150 are rigidly mounted to theircorresponding substrates142.Hollow chamber214, first circuit-mountingopening82c and second circuit-mountingopening82e may be in fluid communication with each other (i.e., form a continuous opening).

Similarly,second wiring harness218 comprises awiring bundle242, a firstelectrical connector246, a secondelectrical connector250, and a thirdelectrical connector254. In this embodiment, firstelectrical connector246 is rigidly mounted tobottom floor86g of first circuit-mountingopening86c so as to be exposed to first circuit-mountingopening86c, and secondelectrical connector250 is rigidly mounted tobottom floor86h of second circuit-mountingopening86e so as to be exposed to second circuit-mountingopening86e.Electrical connector202 ofmeasurement board178 at first circuit-mountingopening86c is connected to firstelectrical connector246, andelectrical connector150 ofmeasurement board138 at second circuit-mountingopening86e is connected to secondelectrical connector250. If desired, firstelectrical connector246 and secondelectrical connector250 may form first and second circuit-mounting structures alone or in combination with their respective first and second circuit-mountingstructures170 and174, especially ifelectrical connector202 is rigidly mounted to its corresponding substrate182 and/or ifelectrical connector150 is rigidly mounted to itscorresponding substrate142.Hollow chamber222, first circuit-mountingopening86c and second circuit-mountingopening86e may be in fluid communication with each other (i.e., form a continuous opening).

As shown inFIGS. 4 and 7, a power source such as abattery unit258 is disposed within ahollow chamber262 incrank axle74.Battery unit258 comprises acylindrical battery housing266 that houses a plurality of individual battery cells (not shown), a firstelectrical connector270 coupled tobattery housing266 throughwiring274, and a secondelectrical connector278 coupled tobattery housing266 throughwiring282. Firstelectrical connector270 is connected to thirdelectrical connector238 offirst wiring harness210 for communicating operating power tomeasurement boards138 at first and second circuit-mountingopenings82c and82e of right crank82 and for communicating sensor signals fromsensors146 onmeasurement boards138 at first and second circuit-mountingopenings82c and82e through bypass wiring (not shown) inbattery housing266. Secondelectrical connector278 is connected to thirdelectrical connector254 ofsecond wiring harness218 for communicating operating power tomeasurement boards178 and138 at first and second circuit-mountingopenings86c and86e of left crank86 and for communicating sensor signals fromsensors146 onmeasurement boards138 at first and second circuit-mountingopenings82c and82e of right crank82 to control andcommunication part190.Wiring harness218 also communicates sensor signals fromsensor146 onmeasurement board138 at second circuit-mountingopening86e of left crank86 to control andcommunication part190.

The sensor mounting arrangements disclosed herein have many uses. For example, as shown inFIG. 8, driving torque F_θmay be detected and processed by mounting measurement boards138 (or178) as shown on upper and lower side surfaces82m,82n ofcrank arm82 so that the sensor mounted on measurement board 138 (or 178) on upper side surface82m detects tension (indicated by arrows) and the sensor mounted on measurement board 138 (or 178) on thelower side surface82n detects compression. As shown inFIG. 9, out-of-plane forces F_zmay be detected and processed by mounting measurement boards138 (or178) as shown on laterally inner andouter side surfaces82d,82f ofcrank arm82 so that the sensor mounted on measurement board 138 (or 178) oninner side surface82d detects compression and the sensor mounted on measurement board 138 (or 178) on theouter side surface82f detects tension (or vice versa). As shown inFIG. 10, forces F_rdirected radially outwardly along the longitudinal axis ofcrank arm82 may be detected and processed by mounting measurement boards138 (or178) as shown on upper and lower side surfaces82m,82n ofcrank arm82 so that the sensor mounted on measurement board 138 (or 178) on upper side surface82m detects tension and the sensor mounted on measurement board 138 (or 178) on thelower side surface82n detects compression. As shown inFIG. 11, torsional moment forces M (caused by a pedal axle286) may be detected and processed by mounting a measurement board138 (or178) diagonally as shown on laterallyouter side surface82f ofcrank arm82 to detect diagonally-oriented tensile forces.

While the above is a description of various embodiments of inventive features, further modifications may be employed without departing from the spirit and scope of the present invention. For example, while first and second wiring harnesses210 and218 were disposed withinhollow chambers214 and222 of crankarms82 and86, respectively, first and second wiring harnesses210 and218 could be molded directly into the corresponding first and second crankarms82 or86. Alternatively, first and second wiring harnesses210 and218 could be partially or entirely disposed outside of first and second crankarms82 and86, andconnectors150 and202 need not be rigidly affixed to the bottom floors of their respective circuit-mounting openings. Likewise,battery unit258 could be disposed partially or entirely outside of crank axle78.

Circuit mounting openings82c,82e,86c and86e may be omitted, andmeasurement boards138 and/or178 may be mounted to circuit mounting structures such as protuberances, circuit mounting structures (e.g., threads) disposed in circuit mounting openings at the side of the crank arm, circuit mounting structures disposed at connectors mounted to the crank arm, etc. Whilemeasurement boards138 and/or178 were mounted to right crank82 and/or left crank86,measurement boards138 and/or178 may be mounted to any such circuit mounting structures290 (FIG. 10), with or without corresponding recesses, disposed on a sprocket mounting arm (spider arm)294 associated withright crank82. Whilemeasurement boards138 and178 were illustrated with onesensor146 and186 each,measurement boards138 and178 may include multiple sensors each.

The size, shape, location or orientation of the various components may be changed as desired. Components that are shown directly connected or contacting each other may have intermediate structures disposed between them. The functions of one element may be performed by two, and vice versa. The structures and functions of one embodiment may be adopted in another embodiment. It is not necessary for all advantages to be present in a particular embodiment at the same time. Every feature that is unique from the prior art, alone or in combination with other features, also should be considered a separate description of further inventions by the applicant, including the structural and/or functional concepts embodied by such feature(s). Thus, the scope of the invention should not be limited by the specific structures disclosed or the apparent initial focus on a particular structure or feature.

Claims (34)

What is claimed is:

1. A bicycle crank arm apparatus comprising:

a crank arm having a crank axle mounting portion and a pedal mounting portion; and

a circuit-mounting structure disposed between the crank axle mounting portion and the pedal mounting portion, wherein the circuit-mounting structure is configured to detachably mount a measurement board having a sensor mounted thereon for measuring an input force.

2. The apparatus according toclaim 1 wherein the circuit mounting structure has an opening.

3. The apparatus according to claim2 34 further comprising a cover that detachably mounts to the circuit-mounting opening.

4. The apparatus according toclaim 2 further comprising an electrical connector disposed at the opening, wherein the connector is configured to detachably connect to another electrical connector.

5. The apparatus according to claim4 34 wherein the electrical connector is disposed within the circuit-mounting opening.

6. The apparatus according toclaim 5 wherein the electrical connector is fastened to the crank arm within the circuit-mounting opening.

7. The apparatus according toclaim 4 further comprising electrical wiring attached to the electrical connector.

8. The apparatus according toclaim 7 wherein the electrical wiring is disposed within the crank arm.

9. The apparatus according toclaim 1 wherein the crank arm includes a sprocket-mounting arm, and wherein the circuit-mounting structure is disposed on the sprocket-mounting arm.

10. A bicycle input force processing apparatus comprising:

a crank arm having a crank axle mounting portion and a pedal mounting portion; and

a first measurement board having a first sensor mounted thereon for measuring a first input force;

wherein the crank arm includes a first circuit-mounting structure disposed between the crank axle mounting portion and the pedal mounting portion and configured to detachably mount the first measurement board.

11. The apparatus according to claim10 26 wherein the first sensor comprises a strain gauge.

12. The apparatus according to claim10 26 wherein the first measurement board includes a surface facing the crank arm, and wherein the sensor is disposed between the surface and the crank arm.

13. The apparatus according to claim10 26 wherein the first circuit mounting structure has an a first circuit-mounting opening.

14. The apparatus according toclaim 13 wherein the first measurement board is mounted within the first circuit-mounting opening.

15. The apparatus according toclaim 14 wherein the first circuit-mounting opening includes a bottom floor so that the first circuit-mounting opening is formed as a recess in the crank arm.

16. The apparatus according to claim10 26 further comprising a fastener that mounts the first measurement board to the first circuit-mounting structure.

17. The apparatus according toclaim 16 wherein the fastener comprises a threaded fastener.

18. The apparatus according to claim10 26 further comprising a transmitter operatively coupled to the first sensor for transmitting sensor signals.

19. The apparatus according toclaim 18 wherein the transmitter wirelessly transmits the sensor signals.

20. The apparatus according toclaim 18 wherein the transmitter is mounted to the first measurement board.

21. The apparatus according toclaim 10 wherein the first measurement board includes a first electrical connector, and wherein the crank arm includes a second electrical connector structured to detachably connect to the first electrical connector.

22. The apparatus according toclaim 21 wherein the second electrical connector is disposed at the opening.

23. The apparatus according toclaim 21 further comprising electrical wiring attached to the second electrical connector.

24. The apparatus according toclaim 23 wherein the electrical wiring is disposed within the crank arm.

25. The apparatus according toclaim 23 further comprising a power source connected to the electrical wiring.

26. The apparatus according toclaim 25 further comprising A bicycle input force processing apparatus comprising:

a crank arm having a crank axle mounting portion and a pedal mounting portion; and

a first measurement board having a first sensor mounted thereon for measuring a first input force applied to the first measurement board by the crank arm;

wherein the crank arm includes a first circuit-mounting structure disposed between the crank axle mounting portion and the pedal mounting portion and configured to detachably mount the first measurement board;

wherein the first measurement board includes a first electrical connector;

wherein the crank arm includes a second electrical connector structured to detachably connect to the first electrical connector;

electrical wiring attached to the second electrical connector;

a power source connected to the electrical wiring; and

a crank axle structured to be mounted to the crank axle mounting portion, wherein the crank axle includes a hollow portion, and wherein the power source is disposed within the hollow portion.

27. The apparatus according toclaim 26 wherein the power source is structured to be detachably connected to the electrical wiring at both ends of the crank axle.

28. The apparatus according to claim10 26 wherein the crank arm includes a second circuit-mounting structure, and further comprising a second measurement board having a second sensor mounted thereon for measuring a second input force applied to the second measurement board by the crank arm, wherein the second circuit-mounting structure is configured to detachably mount the second measurement board.

29. The apparatus according toclaim 28 wherein the first measurement board is disposed at a laterally inner side of the crank arm, and wherein the second measurement board is disposed at a laterally outer side of the crank arm.

30. The apparatus according toclaim 28 wherein the first measurement board is disposed at an upper side of the crank arm, and wherein the second measurement board is disposed at a lower side of the crank arm.

31. A bicycle crank arm apparatus comprising:

a crank arm having a crank axle mounting portion and a pedal mounting portion;

a circuit-mounting structure disposed between the crank axle mounting portion and the pedal mounting portion, wherein the circuit-mounting structure is configured to detachably mount a measurement board having a sensor mounted thereon for measuring an input force applied to the measurement board by the crank arm;

an electrical connector disposed at the circuit-mounting structure, wherein the electrical connector is configured to detachably connect to another electrical connector; and

electrical wiring attached to the electrical connector;

wherein the electrical wiring extends from the circuit-mounting structure into a hollow chamber formed in the crank arm;

wherein the electrical wiring extends from the hollow chamber out of the crank arm; and

wherein the electrical wiring extends out of the hollow chamber through the crank axle mounting portion of the crank arm.

32. The apparatus according to claim 31 wherein the circuit mounting structure has a circuit-mounting opening.

33. The apparatus according to claim 31 wherein the electrical connector is rigidly mounted to the crank arm.

34. The apparatus according to claim 32 wherein the electrical connector is disposed at a bottom floor of the circuit-mounting opening.

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