GB2456821A

GB2456821A - Determining power output from a crank drive by measuring reaction force at the support bearing housing and angular velocity

Info

Publication number: GB2456821A
Application number: GB0801398A
Authority: GB
Inventors: Stephen Davidson
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-01-28
Filing date: 2008-01-28
Publication date: 2009-07-29
Anticipated expiration: 2028-01-28
Also published as: GB2456821B; GB0801398D0

Abstract

Determining power output from a crank drive by measuring the reaction force at the support bearing housing and the angular velocity of the crank drive. The invention is particularly suited for determining the power output at a bicycle crank. One or more crankshaft support bearing housings including rolling element bearings are configured to include load sensors between the bearing outer race and the housing bearing location annular recess such that bearing load is transferred to the bearing housings via the load sensors. The detected load is the reaction force from the bearing housings that is proportional to the applied force at the crank drive. The angular velocity of the crank drive is also measured and from these measurements the power output from the crank drive is calculated. Temperature sensing means are also included, to enable temperature compensation means of the sensors. Electronic means are also provided to collate reaction force and angular velocity data from the sensors, and to wirelessly transmit the data.

Description

Method and apparatus for measuring power output from a crank drive

Background

1. Field of the Invention

This invention generally relates to a method and apparatus for measurement of power output from a reciprocating mechanism supported by a shaft system and bearing assembly such as a bicycle crank.

The system preferably is a bicycle. More specifically the invention relates to a method and apparatus for the measurement of power output of a bicyclist.

2. Background of the invention

Bicycles are widely used for personal transportation, leisure pursuits, maintaining and increasing fitness and for competitive sporting events. There is a general increase in bicycle use for fitness and in competition. To maximise benefit the rider needs to gauge effort expended in real time and to do this accurately the rider power output requires to be calculated accurately in a consistent manner under variable conditions.

This provides the rider with direct feedback of effort independent of other variables such as speed, weather, terrain, heart rate etc. Several devices are currently available on the market to measure the rider power output by various means but this invention permits the accurate measurement of power at the crank drive where rider power output is transferred to propel the machine under a wide range of conditions and terrain types without restriction on crank drive types, pedals or wheels. This invention uses a different force measurement to other devices to calculate power and uses simpler, lower cost technology, can be retrofitted to a machine with the minimum of standard part replacement, is easily calibrated and is portable for use on more than one machine.

3. Statement of invention

The invention broadly provides a method and apparatus for measuring power output of a reciprocating mechanism where the mechanism is a rotating crank supported by bearings. The preferred embodiment of the method and apparatus is a bicycle and the measurement of power of the bicyclist.

The method of the invention comprises measuring the reaction force from the crank shaft support bearing housings when load is applied to the crank during operation and calculating the power output there-from.

The apparatus of the invention includes load sensors fitted to the bearing housings on both sides of the bicycle frame, a speed sensor for the crank rotation, a speed sensor for wheel rotation, a mounting system, a wireless communication system, a computer module and electronic processing means to calculate and display the power output based on the measurements made relating to the forces applied to the crank during rotation.

An apparatus for measuring power transmitted by the cranks comprises a plurality of load sensors fitted to the bearing housings for the supporting bearings and axle assembly to which the cranks are attached.

The load sensors directly measure the reaction force at the bearing locations and coupled with the measurement of crank angular velocity, signals are generated that represent the power output transferred from the bicyclist to the cranks to propel the bicycle. The reaction forces at the bearing housings are directly proportional to the force applied to the rotate the cranks to propel the bicycle. These signals are collated and transmitted by a wireless transmitter module along with crank angular velocity data to a computer module for rider power output to be calculated and displayed.

The computer module calculates and displays the rider power output in real time and also stores the measurements at predefined time intervals for review later or for download to a computer for further analysis.

The computer module also displays additional measurements of road speed, crank revolutions per unit time, speed of variation of load transferred to crank by the rider, left and right crank load imbalance, crank torque and rider heart rate. These measurements are displayed and recorded at predetermined time frames.

The computer module has the facility to output all of the measured and calculated values to another computer in real time to facility laboratory type testing.

In another embodiment the crank shaft assembly (commonly known to those skilled in the art as a bottom bracket assembly), is configured as a replaceable cartridge unit that encloses the load sensors and is fitted to the bicycle as a complete assembly with the crank drive then fitted to the shaft. The bottom bracket assembly complete with load sensors, is intended to be of standard design to accommodate readily available crank drives currently on the market and to fit the majority of bicycle frames available.

In another embodiment the system uses a hard wired communication system between the sensors and the computer module.

The primary object of invention is to provide method and apparatus for measuring the power output from the bicyclist propelling a bicycle.

An additional object of the invention is that it is self contained and is suitable for use on both mobile and stationary bicycles Another object of the invention is that it is simple, inexpensive to manufacture and maintain and is easily mountable.

Another object of the invention is that it does not interfere with normal operation of the crank drive.

These and other objects of the invention will be apparent to one skilled in the art from the following detailed description of specific embodiments thereof.

4. Introduction to drawings

An example of the invention will now be described by referring to the following drawings: Figure 1 is a schematic pictorial view of a typical sports bicycle and rider showing the main bicycle components.

Figure 2 is a schematic pictorial, part sectional, part exploded view of the bottom bracket part of a typical bicycle frame viewed from the rear in accordance with one embodiment of the present invention showing the main components. For clarity sensors are shown shaded and bearing seals and crank detail fittings to the shaft are not shown.

Figure 3 is a side view of one of the bottom bracket bearing housings in accordance with one embodiment of the present invention, (for clarity sensors are shown shaded and bearing seals are not shown).

Figure 4 is a pictorial view of a typical standard bicycle crank drive assembly removed from the bicycle frame.

Figure 5 is a pictorial view of a typical standard bicycle crank drive assembly removed from the bicycle frame as figure 4, with the bearing housings modified in accordance with one embodiment of the present invention.

Figure 6 is a schematic electrical block diagram for one embodiment of the electronics used in connection with the method and apparatus for measuring power output from a crank drive.

Figure 7 shows graphs of typical response from a force sensing resistor in an electrical circuit in accordance with one embodiment of the present invention. The graphs show force Vs resistance and force Vs conductance (1/resistance). The conductance curve is linear.

Figure 8 shows a force sensor response graph as in Figure 7 when incorporated into a force to voltage circuit such that the output voltage varies linearly with force applied.

Figure 9 shows typical torque output profiles from a crank drive over one full revolution from two different bicyclists producing approximately the same power output to show typical torque variation that requires to be measured.

Detailed Description

Description that follows is for one embodiment of the present invention.

In operation of a bicycle the rider power output is transmitted to pedals 7 that are attached to a crank 6a fitted with chain rings 11 a that rotates and drives a flexible member such as a chain 9 to drive a wheel lOb to propel the bicycle (figure 1).

Referring to figure 4, the crank 6a and Gb assembly is normally fitted to the bicycle frame 8 using a shaft and bearing assembly commonly known as a bottom bracket.

The bottom bracket assembly comprises a shaft 22 supported by bearings 3 that are fitted into housings 2c and 2d in order that they can be secured in the bicycle frame 8 and permit the cranks 6a and 6b once fitted to the bottom bracket to freely rotate.

The force exerted by the rider to drive the crank 6a and 6b has reaction components from the bottom bracket bearing housings 2c and 2d that are constrained by the bicycle frame 8. The reaction forces from the bottom bracket bearing housings 2c and 2d are directly proportional to the force applied to the crank 6a and Gb by the rider.

Referring to figure 2, a plurality of load sensors 1 are permanently fitted to the bottom bracket bearing housings 2a and 2b. The bottom bracket bearing housings 2a and 2b are fitted to any standard bicycle frame 8 as would normal bottom bracket bearing housings (figure 5, 2c and 2d), in that they are normally screw fit into the frame 8 where the juncture of the down tube 18, seat tube 19 and chainstays 20 exist.

The bottom bracket bearing housings 2a and 2b are correlated to each other and to the frame 8 in terms of sensor 1 position by using shims 21 a and 21 b and an alignment pin 4 secured by a locking pin 5. It is envisaged that different width shims 21a and 21b may be used to obtain the correct bottom bracket bearing housing 2a and 2b alignment such that the sensor 1 angular positions are the same on each side of the frame 8.

The load sensors 1 are thin film flexible printed circuits that are pressure sensitive.

The load sensors 1 act as variable resistors in an electrical circuit (figure 6). When the sensors 1 are unloaded their resistance is very high. When force is applied to a load sensor 1 the resistance decreases. The change in load sensor 1 resistance measured is directly proportional to force applied.

With a constant voltage applied to the load sensors 1 the output voltage varies linearly with force applied to the sensors 1. The electrical circuit (figure 6) has a reference resistance (RF) for calibration of the load range of the sensor 1. The output voltage is calculated from the following equation: V0 = -VE x (RF/RS) Where: V0 = Output voltage from sensor VE = Excitation voltage RF = Fixed reference resistance (for load range) R5 = Sensor resistance An analogue to digital converter is used in the wireless transmission module 13 to change the voltage to a digital output.

Refer to Figure 7 showing a graph of typical response from a force sensing resistor in an electrical circuit. The graph shows force Vs resistance and force Vs conductance (1/resistance). The conductance curve is linear. When incorporated into a force to voltage circuit, the output voltage varies linearly with force applied as shown in Figure 8.

The load sensors 1 location in the bottom bracket bearing housings 2a and 2b are such that they measure the reaction force from the force applied to rotate the cranks 6a and 6b that are used to propel the bicycle 8. The reaction force in the bearing housings 2a and 2b measured by the load sensors 1, is directly proportional to the torque applied to the cranks 6a and 6b. The unit of torque is Nm (the crank is of known length and the force is measured).

The angular velocity of the crank 6a and 6b is determined by means of a magnet 15 attached to the crank 6a passing a reed switch 16 on one of the bottom bracket bearing housings 2a. The unit of angular velocity (to) is radians per second and is calculated from crank 6a revolutions per minute (known as cadence), from reed switch activation every revolution as follows: W Crpm x (2rrI6O), where: to = angular velocity (rad1) Crpm = cadence in revolutions per minute w=3.14128 With the reaction force from the bottom bracket bearing housings 2a and 2b being directly proportional to the torque applied at the crank 6a and 6b of known length and the crank 6a angular velocity measured, the power supplied by the rider can be calculated from the equation: P = Tw where: P = Power (watts) T = Torque (Nm) w = angular velocity (rad1) As the sensor 1 output voltage is directly proportional to force (in this case the reaction force from the force applied to rotate the crank 6a and 6b), the torque can be calculated as follows: T= (V1-V2) x V x CL where: T = Torque (Nm) V1 = sensor output voltage (loaded state) V2 = sensor output voltage (no load state) V = voltage calibration slope (Voltage change per unit load in Newtons) C1 = crank length (m) Crpm cadence (revolutions per minute) Thus power can be calculated as follows: P = Tw = (Vi-.V2) X Vcai X CL X Crpm X (2w / 60) The no load voltage (V2) along with the voltage calibration slope (V) and crank 6a and 6b length (CL) are input to the computer module 14 as fixed parameters with the other variable parameters being measured to permit correct power calculation in real time.

Referring to Figure 6 the sensor output voltage and cadence data pass through analogue to digital converters to a radio frequency transmitter 13. The signals are sent to a radio frequency receiver in the computer module 14 where there is a micro processor for calculation, display and for storage of the data in memory.

The sum of all of the sensor 1 loads on each bottom bracket bearing housing 2a and 2b is used for the loaded state averaged over each full crank 6a revolution thus total torque and torque for each crank 6a and 6b can be determined.

A plurality of load sensors 1 located in each bearing housing 2a and 2b for the bottom bracket bearings 3a and 3b, are configured to measure the predominant reaction loads at the bottom bracket bearing housings 2a and 2b and in this embodiment are configured at angular positions of: 0 degrees, 45 degrees, 90 degrees, 135 degrees, 180 degrees, 225 degrees, 270 degrees and 315 degrees relative positions from top dead centre (figure 3).

The correct positioning of the bearing housings 2a and 2b in the bicycle frame 8 such that the sensors 1 are in the correct orientation is by means of shim 21 a and 21 b adjustment of the bearing housings 2a and 2b and fitment of an alignment pin 4 to ensure that both bearing housings 2a and 2b are correlated to each other.

The load sensors 1 are calibrated for a zero load condition when cranks 6a and 6b are fitted such that any load applied to the cranks 6a and 6b can then be correctly measured.

In the no load state only the mass of the cranks 6a and 6b and pedals 7 is measured by the load sensors 1 including any static load from fitting. A rider standing on the pedals 7 would provide a load reading but would elicit no power since the crank 6a and 6b must be rotated with load for power to be calculated.

The load sensors 1 are calibrated for zero load by taking the readings from the load sensors 1 whilst the cranks 6a and 6b are rotated without load and stopped at several predefined crank 6a and 6b angular static positions with the readings then stored in the computer module 14. The load sensors 1 can then be calibrated using a known mass on each pedal 7 at the same predefined crank 6a and 6b angular static positions and the load readings thenstored in the computer module 14.

With the known crank arm Ga and 6b length input to the computer module 14 the static no load and loaded readings can then be used as the basis for sensor 1 voltage to load slope calibration. It is envisaged that this type of procedure will only required to be carried out on first installation and then if crank 6a and 6b assembly or pedals 7 are subsequently changed with items that are substantially different.

In one embodiment the load can be distinguished between the left and right cranks 6a and 6b to permit detailed analysis of the pedal 7 stroke and irregularities to help with training to improve efficiency and for rehabilitation analysis. The data can be displayed in real time on the computer module 14 screen and is stored in non volatile memory for download to a computer for detailed analysis.

The load sensors 1 signals are transferred to a computer module 14 via wireless transmission means to permit the calculation of power applied to the cranks 6a and 6b.

The crank 6a and 6b assembly is fitted to standard bicycles in several ways depending on design. In one embodiment the bottom bracket bearings 3 are fitted outboard of the bicycle frame 8 within lightweight housings 2a and 2b and the bottom bracket axle 22 is a push fit through the bearings 3 with one or both of the crank 6a and 6b arms then being fitted such as to secure the assembly in the correct position for use. Referring to figure 3, slots 24 are shown to provide means for the bearing housing 2a to be screw fit into the bicycle frame using simple tooling.

In another embodiment the bottom bracket axle, bearings and bearing housings are fitted to the bicycle frame 8 as one complete assembly with the cranks 6a and 6b then fitted to the axle 22.

In another embodiment the bottom bracket bearing housings 2 are press fit into the frame 8 as opposed to screw fit. In this embodiment the shims 21a and 21b would not be required.

Referring to figure 3, taking one of the bottom bracket bearing housings 2a, the load sensors 1 are fitted to the annular recess of the bearing housing 2a such that the outside diameter of the bearing assembly 27 is only in contact with load sensors 1 and not the bearing housing 2a annular recess. In this configuration the bearing load is transferred to the bearing housing 2a via the load sensors 1 with no intermediate device. The bearing assembly comprises and inner race 29, roIling elements 28 and outer race 27 and has the seals not shown for clarity. The bearing assembly can be a ball bearing or roller bearing type depending on application as required.

In another embodiment the bearing housings 2a and 2b can be configured with small pucks between the housing and the sensors 1 or between the bearing outer race 27 and the sensors 1 to ensure that the load is transferred through the correct sensor location and/or to facilitate manufacture, assembly or different configurations and/or types of sensors.

Referring to figure 2, the sensors 1 are connected to a common power supply (local battery) housed within the wireless transmitter module 13.

The cable connections 26a and 26b with the wireless transmitter module (sockets 25a and 25b) allows for a secure electrical connection for the transfer of the sensor signals. The wireless transmitter module 13 includes a temperature sensor 30 to measure bearing housing 2b temperature for compensation of the load sensorsi to allow for any correction of load sensitivity due to temperature changes during use in real time. The temperature sensor is also powered and signals sent via the cable connection 26b and socket 25b with the wireless transmitter module.

In another embodiment the transmitter module can be connected to the computer module 14 by conductive wire for the transfer of data.

The invention also includes for the measurement of road speed for additional information to the rider. Road speed is determined by use of a magnet 17 affixed to a wheel 10 that passes and activates a reed switch 12 once every wheel 10 rotation to permit the calculation of road speed in the computer module 14 from a known wheel 10 outer diameter that is input to the computer module 14 during set up.

From the foregoing it will be apparent that the power meter can be easily substituted for the standard bottom bracket bearing assemblies and computer. It will also be apparent that the power meter should be easily transferable between different machines either in total or by means of supplementary fitting kits to permit transfer of the computer control module 14 with the other parts (bottom bracket bearing housings 2a and 2b and load sensors 1) remaining fitted to the frame 8.

Various modifications and changes may be made with regard to the foregoing detailed description without departing from the spirit of the invention. Accordingly, the present disclosure is to be taken as illustrative rather than limiting the scope, nature, or spirit of the subject matter claimed below. Numerous modifications and variations will become apparent to those skilled in the art after studying the disclosure, including those of equivalent functional and/or structural substitutes for elements described herein. Such insubstantial variations are to be considered within the scope of what is contemplated here. Moreover, if plural examples are given for specific means and extrapolation between and/or beyond such given examples is obvious in view of the present disclosure, then the disclosure is to be deemed as effectively disclosing and thus covering at least such extrapolations.

Claims

Claims What is claimed is: 1. An apparatus for measuring reaction forces from the support bearing housings for a crank drive comprising: One or more crank shaft support bearing housings adapted and fitted with sensing means to detect reaction load in one or more bearing housings from force applied to the crank during crank rotation, wherein direct connection of the sensing means to one or more bearing housings provides a direct indication of reaction force from the bearing housings to the force applied to rotate the cranks under load, sensing means to detect change in angular position of cranks and rate of rotation, electronic means to collate sensor signals and configured to wirelessly transmit the electrical data, a housing substantially enclosing the wireless transmission means whilst facilitating the electrical coupling between the sensing means and the wireless transmission means and a temperature sensor fitted to one or more bearing housings to facilitate temperature compensation of sensing means.
2. The power measuring apparatus as claimed in claim 1, further comprising means to receive, process, display and store electrical data from the wireless transmission means, wherein the means is includes a power supply.
3. The power measuring apparatus as claimed in claim 1, wherein the force measured by the sensors is directly proportional to force applied to the crank.
4. The power measuring apparatus as claimed in claim 1, wherein a plurality of load sensors are mounted in at least one crank axle support bearing housing to detect reaction force from the bearing housing to the force applied at the crank during rotation.
5. The power measuring apparatus as claimed in claim 4, wherein the plurality of load sensors are mounted between the bearing housing and the outer race of the support bearing such that any bearing load must be transferred from the crankshaft support bearing to the housing via the load sensors.
6. The power measuring apparatus as claimed in claim 4, wherein the plurality of load sensors are connected to a lightweight portable power supply (battery or cell) to maintain a predetermined voltage for sensor operation.
7. The power measuring apparatus as claimed in claim 4, wherein crank shaft bearing housings and sensor positions are aligned in order that crank position can be determined during calibration and operation.
8. The power measuring apparatus as claimed in claim 4, wherein the crank position is determined relative to the sensors by a magnet fixed to one of the crank arms passing in proximity to a reed switch mounted on the bearing housing aligned with one of the load sensors and mounted adjacent to the crank.
9. The power measuring apparatus as claimed in claim 6, wherein the signal generation is by electronic means
1 0.The power measuring apparatus as claimed in claim 4, wherein the load sensor output signals are collated and transferred to a means for calculation, display and storage of the electrical data from the wireless transmission means.
11. The power measuring apparatus as claimed in claim 10, wherein the electrical signal interpretation is carried out in the means for reception, calculation, display and storage of the electrical signals from the wireless transmission means, to display calculated power in real time.
12. The power measuring apparatus as claimed in claim 11, wherein the calculated power can be displayed in real time and/or averaged over predetermined time intervals.
13.The power measuring apparatus as claimed in claim 9, wherein the collation of the load sensor signals is by electronic means
14. The power measuring apparatus as claimed in claim 4, wherein the load sensors are calibrated for zero load when fitted such that any change in load during rotation of the crank can be detected.
15. The power measuring apparatus as claimed in claim 14, wherein the calibration for zero load can be carried out using the means for reception, calculation, display and storage of the electrical signals from the wireless transmission means and by rotating the crank in a no load condition.
16. The power measuring apparatus as claimed in claim 1, wherein a temperature sensor is fitted to one or more of the bearing housings for temperature compensation calibration of the load sensors during operation.
1 7.The power measuring apparatus as claimed in claim 8, wherein a magnet fixed to one of the crank arms passing in proximity to a reed switch mounted on the bearing housing aligned with one of the load sensors, generates a signal indicative of angular velocity of the driven crank.
18. The power measuring apparatus as claimed in claim 7, wherein the plurality of sensor positions can be aligned by means of bearing housing fitting shims and an alignment pin to ensure correct sensor position when the bearing housings are fitted to the bicycle frame by a screw fit method.
1 9.The power measuring apparatus as claimed in claim 7, wherein the plurality of sensor positions can aligned by means of an alignment pin to ensure correct sensor position when the bearing housings are fitted to the bicycle frame by a press fit method.
20. The power measuring apparatus as claimed in claim 7, wherein the plurality of sensor positions can aligned by means of bearing housing fitting shims when the bearing housing, bearings, sensors and crankshaft are fitted as one complete assembly to the bicycle frame by a screw fit method.
21.The power measuring apparatus as claimed in claim 1, wherein the load sensors are static dunng operation.
22. The power measuring apparatus as claimed in claim 8, wherein the means for producing a crank rotational signal is mounted on a bearing housing and one of the crank arms
23. The power measuring apparatus as claimed in claim 2, wherein the known parameters such as crank length from axle centre to pedal axle centre is input to the means for reception, calculation, display and storage of the electrical signals from the wireless transmission means manually to enable correct calculation of applied torque during rotation
24. The power measuring apparatus as claimed in claim 10, wherein the signals are filtered to avoid erroneous signals from external sources
25. The power measuring apparatus as claimed in claim 2, wherein the calculated power output of the bicyclist is displayed in real time for the purpose of direct effort feedback.
26. The power measuring apparatus as claimed in claim 25, wherein the displayed power output is stored for download at predetermined time intervals.
27. The power measuring apparatus as claimed in claim 1, wherein the speed of rotation by means of cadence signal is calculated and stored with the power data in the same time frame.
28. The power measuring apparatus as claimed in claim 1, wherein the torque related to crank position for left and right cranks is displayed in real time on the means for reception, calculation, display and storage of the electrical signals from the wireless transmission means and is stored for download at predetermined time intervals.
29. The power measuring apparatus as claimed in claim 1, wherein the power measuring apparatus can be applied to any reciprocating mechanism with cyclic power input or output.
30. The power measuring apparatus as claimed in claim 10, wherein the means for transmitting the signals comprises a radio frequency (RF) transmitter.
31.The power measuring apparatus as claimed in claim 1, wherein the apparatus can be fitted and removed easily.
32. The power measuring apparatus as claimed in claim 1, wherein the crankshaft and crank assembly is fitted to a bicycle for the purpose of propulsion of the bicycle.
33.A method of determining power output from a crank drive by measuring the reaction force at the support bearing housings and the angular velocity of the crank drive.
34. The method as claimed in claim 33, further comprising a plurality of load sensors mounted between the bearing housing and the outer race of the crankshaft support bearing such that any bearing load must be transferred from the bearing to the housing via the load sensors.
35. The method as claimed in claim 34, wherein the load measured by the sensors is directly proportional to force applied to the crank.
36. The method as claimed in claim 34, wherein a plurality of load sensors are mounted in at least one crank axle support bearing housing to detect reaction force from the bearing housing to the force applied at the crank during rotation.
37. The method as claimed in claim 34, wherein the plurality of load sensors are connected to a lightweight portable power supply (battery or cell) to maintain a predetermined voltage for sensor operation.
38. The method as claimed in claim 34, wherein crank shaft bearing housings and sensor positions are aligned in order that crank position can be determined during calibration and operation.
39. The method as claimed in claim 34, wherein the crank position is determined relative to the sensors by a magnet fixed to one of the crank arms passing in proximity to a reed switch mounted on the bearing housing aligned with one of the load sensors and mounted adjacent to the crank.
40.The method as claimed in claim 34, wherein the load sensors are calibrated for zero load when fitted such that any change in load during rotation of the crank can be detected.
41.The method as claimed in claim 40, wherein the calibration for zero load can be carried out using the means for calculation, display and storage of the electrical data and by rotating the crank in a no load condition.
42. The method as claimed in claim 34, wherein the plurality of sensor positions can be aligned by means of bearing housing fitting shims and an alignment pin to ensure correct sensor position when the bearing housings are fitted to the bicycle frame by a screw fit method.
43. The method as claimed in claim 34, wherein the plurality of sensor positions can be aligned by means of an alignment pin to ensure correct sensor position when the bearing housings are fitted to the bicycle frame by a press fit method.
44. The method as claimed in claim 34, wherein the plurality of sensor positions can be aligned by means of bearing housing fitting shims when the bearing housing, bearings, sensors and crankshaft are fitted as one complete assembly to the bicycle frame by a screw fit method.
45. The method as claimed in claim 34, wherein the load sensors are static during operation.
46. The method as claimed in claim 39, wherein the means for producing a crank rotational signal is mounted on a bearing housing and one of the crank arms
47. The method as claimed in claim 33, wherein the torque related to crank position for left and right cranks is displayed in real time on the computer module and is stored for download.
48.The method as claimed in claim 34, wherein the power measuring apparatus can be applied to any reciprocating mechanism with cyclic power input or output.

48. The method as claimed in claim 34, wherein the power measuring apparatus can be applied to any reciprocating mechanism with cyclic power input or output. iLf

Claims Amendments to the Claims have been filed as follows What is claimed is: 1. A power measuring apparatus whereby the power output is determined from measurement of the reaction forces from the support beanng housings for a crank drive and the crank angular velocity with the apparatus comprising: One or more crank shaft support bearing housings adapted and fitted with a plurality of load sensors mounted between the bearing housing and bearing outer race to detect reaction load in one or more bearing housings from force applied to the crank during crank rotation, wherein direct connection of the sensing means to one or more bearing housings provides a direct indication of reaction force from the bearing housings to the force applied to rotate the cranks under load, sensing.

means to detect change in angular position of cranks and rate of rotation, electronic means to collate sensor signals and configured to wirelessly transmit the electrical data, a housing substantially endosing the wireless transmission means whilst facilitating the electrical coupling between the sensing means and the wireless transmission means and a temperature sensor fitted to one or more bearing housings to facilitate temperature compensation of sensing means.

2. The power measuring apparatus as daimed in claim 1, further comprising means to receive, process, display and store electrical data from the wireless transmission means, wherein the means includes a power supply.

***. 3. The power measuring apparatus as daimed in claim 1, wherein the force measured by the sensors is directly proportional to force applied to the crank.

4. The power measuring apparatus as claimed in claim 1, wherein a plurality of load sensors are mounted in at least one crank axle support bearing housing to detect * reaction force from the bearing housing to the force applied at the crank during rotation.

* 5. The power measuring apparatus as daimed in claim 4, wherein the plurality of * load sensors are mounted between the bearing housing and the outer race of the support bearing such that any bearing load must be transferred from the crankshaft support bearing to the housing via the load sensors.

6. The power measuring apparatus as claimed in claim 4, wherein the plurality of load sensors are connected to a lightweight portable power supply (battery or cell) to maintain a predetermined voltage for sensor operation.

7. The power measuring apparatus as daimed in claim 4, wherein crank shaft bearing housings and sensor positions are aligned in order that crank position can be determined during calibration and operation.

8. The power measuring apparatus as claimed in claim 4, wherein the crank position is determined relative to the sensors by a magnet fixed to one of the crank arms passing in proximity to a reed switch mounted on the bearing housing aligned with one of the load sensors and mounted adjacent to the crank. is

9. The power measuring apparatus as claimed in claim 6, wherein the signal generation is by electronic means 10. The power measuring apparatus as claimed in claim 4, wherein the load sensor output signals are collated and transferred to a means for calculation, display and storage of the electrical data from the wireless transmission means.

11. The power measuring apparatus as claimed in claim 10, wherein the electrical signal interpretation is carried out in the means for reception, calculation, display and storage of the electrical signals from the wireless transmission means, to display calculated power in real time.

12. The power measuring apparatus as claimed in claim 11, wherein the calculated power can be displayed in real time and/or averaged over predetermined time intervals.

13.The power measuring apparatus as claimed in claim 9, wherein the collation of the load sensor signals is by electronic means 14. The power measuring apparatus as claimed in claim 4, wherein the load sensors are calibrated for zero load when fitted such that any change in load during rotation of the crank can be detected.

15. The power measuring apparatus as claimed in claim 14, wherein the calibration for zero load can be carried out using the means for reception, calculation, display and storage of the electrical signals from the wireless transmission means and by rotating the crank in a no load condition.

16. The power measuring apparatus as claimed in claim 1, wherein a temperature sensor is fitted to one or more of the bearing housings for temperature compensation calibration of the load sensors during operation.

17. The power measuring apparatus as claimed in claim 8, wherein a magnet fixed to one of the crank arms passing in proximity to a reed switch mounted on the bearing housing aligned with one of the load sensors, generates a signal indicative of angular velocity of the driven crank.

18. The power measuring apparatus as claimed in claim 7, wherein the plurality of sensor positions can be aligned by means of bearing housing fitting shims and an alignment pin to ensure correct sensor position when the bearing housings are fitted to the bicycle frame by a screw fit method.

1 9.The power measuring apparatus as claimed in claim 7, wherein the plurality of sensor positions can aligned by means of an alignment pin to ensure correct sensor position when the bearing housings are fitted to the bicycle frame by a press fit method.

20. The power measuring apparatus as claimed in claim 7, wherein the plurality of sensor positions can aligned by means of bearing housing fitting shims when the bearing housing, bearings, sensors and crankshaft are fitted as one complete assembly to the bicycle frame by a screw fit method.

21.The power measuring apparatus as claimed in claim 1, wherein the load sensors are static dunng operation.

22. The power measuring apparatus as claimed in claim 8, wherein the means for producing a crank rotational signal is mounted on a bearing housing and one of the crank arms 23. The power measuring apparatus as claimed in claim 2, wherein the known parameters such as crank length from axle centre to pedal axle centre is input to the means for reception, calculation, display and storage of the electrical signals from the wireless transmission means manually to enable correct calculation of applied torque during rotation 24. The power measuring apparatus as claimed in claim 10, wherein the signals are filtered to avoid erroneous signals from external sources 25. The power measuring apparatus as claimed in claim 2, wherein the calculated power output of the bicyclist is displayed in real time for the purpose of direct effort feedback.

26. The power measuring apparatus as claimed in claim 25, wherein the displayed power output is stored for download at predetermined time intervals.

27. The power measuring apparatus as claimed in claim 1, wherein the speed of rotation by means of cadence signal is calculated and stored with the power data in the same time frame.

28. The power measuring apparatus as claimed in claim 1, wherein the torque related to crank position for left and right cranks is displayed in real time on the means for reception, calculation, display and storage of the electrical signals from the wireless transmission means and is stored for download at predetermined time intervals.

29. The power measuring apparatus as claimed in claim 1, wherein the power measuring apparatus can be applied to any reciprocating mechanism with cyclic power input or output.

30. The power measuring apparatus as claimed in claim 10, wherein the means for transmitting the signals comprises a radio frequency (RE) transmitter.

31.The power measuring apparatus as claimed in claim 1, wherein the apparatus can be fitted and removed easily. I.

32. The power measuring apparatus as claimed in claim 1, wherein the crankshaft and crank assembly is fitted to a bicycle for the purpose of propulsion of the bicyde.

33.A method of determining power output from a crank drive by measuring the reaction force at one or more support bearing housings and the angular velocity of the crank drive whereby the reaction force is measured between the bearing housings and the bearing outer races.

34. The method as claimed in claim 33, further comprising a plurality of load sensors mounted between the bearing housing and the outer race of the crankshaft support bearing such that any bearing load must be transferred from the bearing to the housing via the load sensors.

35. The method as daimed in claim 34, wherein the load measured by the sensors is directly proportional to force applied to the crank.

36. The method as daimed in claim 34, wherein a plurality of load sensors are mounted in at least one crank axle support bearing housing to detect reaction force from the bearing housing to the force applied at the crank during rotation.

37. The method as claimed in claim 34, wherein the plurality of load sensors are connected to a lightweight portable power supply (battery or cell) to maintain a predetermined voltage for sensor operation.

38.The method as daimed in claim 34, wherein crank shaft bearing housings and * .* sensor positions are aligned in order that crank position can be determined during calibration and operation.

39. The method as claimed in claim 34, wherein the crank position is determined * relative to the sensors by a magnet fixed to one of the crank arms passing in proximity to a reed switch mounted on the bearing housing aligned with one of the load sensors and mounted adjacent to the crank. **

40. The method as claimed in daim 34, wherein the load sensors are calibrated for zero load when fitted such that any change in load during rotation of the crank can be detected.

41.The method as claimed in claim 40, wherein the calibration for zero load can be camed out using the means for calculation, display and storage of the electrical data and by rotating the crank in a no load condition.

42.The method as claimed in claim 34, wherein the plurality of sensor positions can be aligned by means of bearing housing fitting shims and an alignment pin to ensure correct sensor position when the bearing housings are fitted to the bicycle frame by a screw fit method.

43. The method as claimed in claim 34, wherein the plurality of sensor positions can be aligned by means of an alignment pin to ensure correct sensor position when the bearing housings are fitted to the bicyde frame by a press fit method.

44. The method as claimed in claim 34, wherein the plurality of sensor positions can be aligned by means of bearing housing fitting shims when the bearing housing, bearings, sensors and crankshaft are fitted as one complete assembly to the bicycle frame by a screw fit method.

45.The method as claimed in claim 34, wherein the load sensors are static during operation.

46. The method as claimed in claim 39, wherein the means for producing a crank rotational signal is mounted on a bearing housing and one of the crank arms 47. The method as claimed in claim 33, wherein the torque related to crank position for left and right cranks is displayed in real time on the computer module and is stored for download.