WO2007115073A2

WO2007115073A2 - Power meter for deriving elevational changes of a bicycle ride

Info

Publication number: WO2007115073A2
Application number: PCT/US2007/065462
Authority: WO
Inventors: Edward M. Watson
Original assignee: Saris Cycling Group, Inc.
Priority date: 2006-03-30
Filing date: 2007-03-29
Publication date: 2007-10-11
Also published as: WO2007115073A3

Abstract

Power measurements are acquired during a bicycle ride and elevation change information is derived therefrom. The elevation information can be determined and displayed during the πde by a bicycle (10) mounted power meter or remote from the bicycle on a computer (28) for post-ride analysis. In addition to providing gradient feedback, the gradient information can also be used to more accurately fashion a simulation of the ride on a simulation device.

Description

POWER METER FOR DERIVING ELEVATIONAL CHANGES OF A BICYCLE RIDE

Inventor:

Edward M. Watson

POWER METER FOR DERIVING ELEVATIONAL CHANGES OF A BICYCLE RIDE

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application 60/743,967, filed March 30, 2006, the disclosure of which is incorporated herein.

BACKGROUND OF THE INVENTION

The present invention is generally directed to biometric monitoring to assess cyclist performance and, more particularly, to a system that derives elevation changes of a bicycle ride, or interval thereof, using power information acquired during the bicycle ride, or interval thereof.

Power is generally defined as the amount of work performed as a function of time. Work is generally defined as the product of the amount of force applied across a given distance. In the context of cycling, power corresponds to the amount of torque a cyclist placed on a bicycle, or similar wheeled device, to move the bicycle between locations. Thus, for a cyclist, to generate the most power, the cyclist must pedal the bicycle at the highest gear possible as the bicycle is ridden along a surface from one location to the next. Because a bicycle will move in fewer pedal revolutions when in a higher gear, the more power a cyclist expends during the ride, the sooner the cyclist will cover the distance between locations. In other words, in the context of a race, the cyclist that works the hardest over the longest period of time (expends the most power) will win the race.

Competitive cyclists, and increasingly, recreational cyclists, are using power meters as training tools to provide quantified feedback regarding the amount of work or energy expended during the course of a ride to aid in optimizing training and/or conditioning. Accordingly, a power meter or power measuring system is typically being used to measure the amount of energy that a cyclist applies onto the bicycle pedals, derive a power value as measured in watts, and display the power value to the cyclist on a multi-functional display that is mounted typically to the handlebar of the bicycle. This provides the cyclist with real-time feedback as to the amount of energy that is being expended during the course of the ride or interval of ride.

To measure power, most power meters measure the torque placed on the bicycle and the speed at which the bicycle is traveling. Power meters will also measure ride distance, total accumulated distance, ride time, time of day, cadence, and the total work done or energy expended. During the course of a ride, the cyclist, with appropriate inputs to the power meter or interface thereof, can cycle through these parameters and the associated measured values displayed on the multifunctional display. The power meter will typically also include a memory that stores measured values during a ride, interval(s), or multiple rides to provide historical measurements, such as maximum power and maximum speed, as well as mathematical measurements, such as average power and average speed. Some power meters will include a heart rate monitor and display the measured heart rate value on the multi-functional display. Similar to the biometric parameters above, heart rate values may be stored and used to provide a maximum heart rate value and an average heart rate value for a given ride or interval. Additionally, heart rate information together with cyclist age and weight (mass) information can be processed by the computer to derive other biometric information, such as total calories burned and calories burned per hour. Exemplary power meters include the PowerTap line of power meters commercially available from Saris Cycling Group, Inc. of Madison, Wisconsin.

One exemplary power meter is the PowerTap SL 2.4. This power meter as well as other power meters, such as that described in U.S. Patent No. 6,418,797, the disclosure of which is incorporated herein by reference, derives power by measuring the torque applied to the hub of the driven wheel of the bicycle and by measuring wheel speed. More particularly, the power meter includes a strain gauge that is mounted on one of the components of the bicycle that couples torque through the driven wheel of the bicycle. The detected strain is used to determine an applied torque on the driven hub. The value of applied torque is then multiplied to an angular velocity value, as measured by rotation of the driven wheel, to derive a power measurement. The power measurement is then displayed in watts to the cyclist and stored for subsequent processing, similar to that described above. As noted above, the power measurement as will as other measurements can be used to assess cyclist performance during the bicycle ride, or interval(s) thereof.

To provide additional feedback, cyclists are increasingly using global positioning system (GPS) receivers that communicate with orbital satellites of the GPS network to acquire real-time location information. In this regard, the GPS receiver can provide a real-time location of the bicycle that, when acquired over time, can be used to track the bicycle as it is pedaled between locations. Moreover, the receiver may include software that processes location information to derive values related thereto, such as distance traveled. The GPS receiver, together with appropriate software, may also be used to outline a track of travel for a planned ride that avoids busy streets, multi-lane roads, and numerous lights, for example. Because the GPS receiver tracks the position of the bicycle relative to a global coordinate system, information associated with each detected location along the bicycle's path may also be determined. For example, natural or man-made landmarks may be located and displayed relative to the bicycle's path to assist the cyclist with navigation. Moreover, elevation values can be determined at a first detected bicycle location and a second detected bicycle location, and then appropriately processed to determine a gradient or slope between the two bicycle locations.

Currently, to take advantage of power meter information and GPS information, two separate devices must be used. While the GPS receiver could be attached to the cyclist, generally, the

GPS receiver and the power meter are mounted directly to the bicycle. Moreover, as each device typically includes a display to provide visual or graphical feedback, separate displays must be mounted within a line-of-sight of the cyclist. Typically, this results in both displays being mounted to the handlebar of the bicycle. Given other mountings to the handlebar, such as break handles, it can be difficult to find sufficient space for the mounting of two separate displays.

Moreover, the GPS information is not integrated with the measurements provided by the power meter. As such, the cyclist must separately evaluate the information to gain a fuller understanding of the particulars of the ride, or intervals thereof. For example, increasingly, as noted above, GPS receivers and power meters store information in a manner that can be downloaded to a computer containing GPS-related software programs and power meter-related software programs. The GPS software may generate a map, relative to one or more topographical or geographical landmarks of the ride and derive particulars associated therewith, such as elevation changes. The power meter software may generate graphs, tables, or charts associated with cyclist bio-performance during the ride, or intervals thereof. Because these programs are separate from one another, they independently process and display the acquired information, thereby requiring any synthesis of the information to be done manually by the cyclist or other user.

For instance, if the cyclist wants to know the power associated with a particular hill climb as well as the hill's gradient, the cyclist must review the power meter information to determine the power value in a window provided by the power meter software and then must review, or determine, the gradient of the hill in a separate window provided by the GPS software. In the isolated example of a single interval or single hill climb, this may not be arduous, but for a multi- interval ride covering a great distance, this can be time-consuming and difficult. Moreover, comparing performance over multiple gradients can be difficult.

An integrated power meter and GPS system, and an integrated software program, may resolve some of these issues associated with separate systems. However, such an integrated system would still be susceptible to the drawbacks of conventional GPS systems. For example, the accuracy of the GPS information is predicated upon the GPS receiver's ability to communicate with the orbital satellites of the GPS system. If the receiver is unable to effectively communicate with the satellites, accurate GPS information cannot be acquired. Moreover, a cyclist may not be aware that communication has failed or, given the location of the bicycle when communication is lost, be able to reestablish effective communication. For example, accurate GPS readings may be difficult to obtain during mountain ascents and descents.

BRIEF DESCRIPTION OF THE INVENTION

The present invention is directed to a power measuring apparatus that acquires conventional biometric and nower information, such as applied torque and angular velocity, and determines information that heretofore was provided by a GPS receiver or other device, such as an altimeter. More particularly, the strain placed on a strain gauge or similar sensor to determine an applied torque applied by a cyclist to a bicycle, or other humanly powered wheeled device is measured. Together with measurements of angular velocity (wheel speed) and distance traveled between two locations, the amount of energy or work expended to pedal the bicycle the distance traveled as a function of time is determined. In addition to this conventional derivation of power, the power measuring apparatus also uses the power measurements to derive a change in elevation between the two locations. A value of this elevation change or gradient can then be displayed and/or used for post-ride analysis.

In addition to post-ride analysis, the power and gradient information can be used for simulation or re-creation of the ride, or portions thereof, on a humanly powered simulation device, such as an indoor rider, roller, or trainer, such as those commercially available from Saris Cycling Group, Inc. of Madison, Wisconsin. Specifically, gradient and distance information can be input to an electronic resistance unit of the simulation device which fashions a simulated ride that is substantially identical, including gradients encountered and distance traveled, to the actual ride. As such, the cyclist can then more accurately compare a simulated ride on the simulation device to the actual ride. For instance, the time needed to pedal the bicycle the traveled distance can be compared to the time required to complete the same track on the simulation device. If the simulated track is completed more quickly, the cyclist knows that more power was used in the simulated ride than in the actual ride.

Therefore, in one aspect, the present invention provides a power measuring apparatus that derives elevation change or gradient information from power measurements. In another aspect, acquired power measurements are input to a computer that derives elevation change or gradient information therefrom. In yet a further aspect, a humanly powered simulation device may be programmed to present a ride that includes the distance and gradient changes that were encountered during the actual ride, wherein the gradient changes are derived from power measurements acquired during the actual ride. Various other features and advantages of the present invention will be made apparent from the following detailed description and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate one preferred embodiment presently contemplated for carrying out the invention.

In the drawings:

Figure 1 is a pictorial view of a bicycle having a power measuring system according to one embodiment of the present invention;

Figure 2 is a flow chart setting forth the steps of deriving gradient information according to a further embodiment of the present invention;

Figure 3 is a schematic view illustrating use of data acquired with the power measuring system to define a simulated ride on a simulation device according to another embodiment of the present invention;

Figure 4 is a representative gradient map from biometric information acquired during a ride that may be displayed on a display unit in an interactive manner;

Figure 5 is a chart showing power-speed curves for two exemplary rides illustrating the impact of aerodynamic drag, environmental wind conditions, and other error sources on power measurements as a function of bicycle speed; and

Figure 6 is a front elevation view of a computer of the power measuring system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In a bicycle or other human-powered wheeled device, it is possible to determine power (in watts) by measuring applied torque and angular velocity. A system of this type is embodied in the POWERTAP line of power meters, which is available from Saris Cycling Group, Inc. of

Madison, Wisconsin. An exemplary POWERTAP power meter is described in Ambrosina et al., U.S. Patent 6,418,797 issued July 16, 2002, the disclosure of which is hereby incorporated by reference. In a system of this type, torque applied by a user to impart rotation to a driven wheel is measured, and the torque information is combined with angular velocity information to determine applied power. Other devices are known for measuring power applied by a user to impart rotation to a driven wheel of a bicycle, and can also be utilized with the present invention. In the paragraphs hereafter, the present invention will be described with respect to measuring power information and deriving elevation changes therefore from a bicycle driven by a single cyclist; however, it is contemplated that the present invention may be applicable with other humanly-powered wheeled devices, including such devices that are powered by multiple cyclists.

Figure 1 contains a schematic pictorial view of a bicycle 10 equipped with one embodiment of a bicycle power measuring system in accordance with the invention. The bicycle 10 includes a pair of pedals 12 connected by crank arms 14 to a chain ring 16. The chain ring 16 is coupled to the hub assembly 18 of the rear wheel 20 by a chain 22. The bicycle 10 is powered by a cyclist (not shown) providing rotational forces to the chain ring 16 via the pedals 12 and crank arms 14. The rotation of the chain ring 16 is transferred by the chain 22 to the rear wheel hub assembly 18 which carries the rear wheel 20 into rotation via spokes 24 to drive the bicycle 10 into motion.

The rear wheel hub assembly 18 senses the torque in and angular velocity of the driven rear wheel 20 of the bicycle 10. The detected torque-related and/or angular velocity-related values are processed by electronics within the hub assembly 18 which transmit these values, such as by radio frequency waves, to a receiver module 26, which can be mounted as shown on either the chain stays or seat stays of the bicycle 10. Alternatively, the data values can be transmitted to the receiver module 26 via inductive coupling or infrared link. The receiver module 26 transmits the information tn the cycle computer 28 which can be mounted on the handlebar 30 of the bicycle 10. In another embodiment, the information can be transferred directly to the computer 28 via RF or infrared link. The computer 28 can use the strain and/or angular velocity information to compute torque and/or power and can display the measured and/or calculated information on a display, as desired. The computer 28 is preferably mounted to the handlebar 30 using a mount (not shown) that allows the computer to be quickly and repeatedly mounted to and removed from the bicycle.

An optional rear wheel magnet 32 can be used that activates an integral reed switch in the receiver module 26, thereby providing angular velocity, speed, and distance measurements to the cycle computer 28 in the absence of, or in addition to, the sensing functions of the hub assembly 18.

Computer 28 is an application specific computing device that includes software to derive performance information based on measured values acquired from the bicycle 10, such as angular velocity, strain, and distance traveled, as well as information acquired directly from the cyclist, such as heart rate, using an integrated heart rate monitor (not shown), as known in the art. Moreover, the computer 28 includes a stored program that causes the computer to determine changes in elevation encountered by the cyclist during a ride, or portions thereof.

Referring now to FIG. 2, the steps of a process executed by the computer 28 to derive elevation change information are set forth. The computer 28 acquires strain and angular velocity information from the receiver module 26 at block 34. The computer then computes a measured power value at block 36. The measured power value is defined as:

Power (watts) = strain x angular velocity (Eqn. 1).

Since measured power can be generally defined as:

Power (watts) = energy (joules)/time (sec) (Eqn. 2), the computer 28 can calculate the cyclist's energy output during the course of a ride, or interval thereof. In this regard, the computer 28 determines the amount of time the cyclist needed to move the bicycle along a surface from a starting point, e.g., start of ride, to a finishing point, e.g., end of ride, at block 38. It is noted that the starting point could also be the start of an interval and the finishing point could be the end of the interval for which the cyclist desired to determine a gradient change rather than starting and finishing points of the ride as a whole.

With the measured power value calculated at block 36 and the time information acquired or otherwise determined at block 38, the computer 28 can compute the cyclist's energy output at block 40 from the following:

Energy (joules) = power x time (Eqn. 3).

Moreover, since:

Energy (joules) = rolling resistance + kinetic energy (KE) + potential energy (PE) (Eqn. 4),

where: rolling resistance = relative constant (K₁), kinetic energy (KE) = Vi x mass x (angular velocity) , and potential energy (PE) = mass x gravity x height (gravity = 9.8 meters/sec ,

the computer 28 can compute the change in elevation between the starting point and the finishing point of the ride at block 44. Specifically, by determining the cyclist's mass (weight) at block 42, and with the already acquired angular velocity information, the computer 28 can solve the following equation:

ΔH = (Δpower x time - K₁- - l/2m Δv²)/m x g; in meters (Eqn. 5).

In the above equation, mass (m) and gravity (g) are known constants. Additionally, in a nreferred embodiment, the cyclist establishes a mass or weight value during programming of the computer in which various values are stored in memory of the computer 28, such as cyclist age and the aforementioned mass, hi this regard, at block 42, in a preferred embodiment, the computer 28 recalls the cyclist's mass value from the memory rather than prompting the cyclist to enter a mass value. Similarly, the memory within the computer 28 contains the gravity value of 9.8.

Thus, using this formulaic relationship, the computer can calculate changes in height at periodic time intervals, without the use of a GPS or GIS system. Those periodic time intervals may include a single time interval defined by the entire ride or may represent various intervals defined within the ride. Moreover, the computer may be programmed to provide real-time and intermittent gradient information by intermittently determining gradient information and then displaying a gradient reading to the cyclist when the cyclist toggles to a corresponding menu or screen on the computer display.

In addition to computing elevation changes or gradient information and displaying that information to the cyclist in real-time on the computer display mounted to the bicycle, a computer, such as a notebook computer, could download the data from computer 28 and determine the gradient and other performance metrics on a post-ride analysis, hi addition, the gradient information can also be used during creation of a simulated ride that simulates the actual ride in which the gradients were encountered by the cyclist.

As is known in the art, various indoor training devices have been designed to provide additional training tools for cyclists. Exemplary indoor training devices include indoor riders, rollers, and trainers available from Saris Cycling Group of Madison, Wisconsin. These and other training devices typically include an electronic resistance unit that can be programmed to provide a desired resistance, or resistance changes, for a simulated ride. Specifically, and with reference to FIG. 2, actual ride data may be acquired from the computer 28 by a general purpose computer, such as notebook computer 46. The notebook computer 46 includes software that processes actual ride data acquired from the computer 28 and from that data devises a simulated ride that is designed to mimic the actual ride. The simulated ride parameters can be then be input to the electronic resistance unit of the simulation device 48. The cyclist can thus re-ride the actual ride

10 on the simulation device 48 and compare biometric and other information for the simulated ride with the actual ride to assess differences in performance. The present invention also provides gradient information in addition to conventional power measurements to provide greater accuracy in fashioning the simulated ride.

Specifically, in contrast to conventional tools, the present invention can associate power measurements with gradient changes so that power measurements, and the context in which they were acquired, are properly simulated. For example, in conventional tools, an interval marked by a gradual increase in power will be simulated in the simulated ride as a gradual increase in resistance to replicate a hill climb. However, the gradual increase in power may not be the result of a hill climb, but may be the result of the cyclist pedaling faster during that interval without experience a gradient change. That is, as noted above, applied power is a function of applied torque and angular velocity. Thus, applied power can increase if applied torque increases and angular velocity either remains constant or increases. Similarly, applied power may increase if angular velocity increases and applied torque remains constant or increases. In the former situation, the applied torque may increase because the cyclist is performing a hill climb and does so without a drop in speed. However, it is also possible for the power to increase because the cyclist is simply pedaling faster (increasing angular velocity) without a gradient change. Conventional tools would adjust the resistance to mimic the change in power but the cyclist would not know that the power change was a result of a hill climb or faster speed during the actual ride. By deriving elevation change information, the present invention augments the conventional power measurements so that a cyclist would be able to determine that the change in power was a result of gradient change.

Because elevation change information is derived from the power measurements rather than a separate elevation determining device, such as a GPS receiver or altimeter, the present invention also provides for interactive assessment of power and other biometric information with gradient information. For example, using appropriate software, the gradient information can be used to derive a gradient map 50, as illustrated in FIG. 4. While the gradient map 50 could be displayed on computer 28 in real-time or after conclusion of a ride on the notebook computer 46.

11 As noted above, the notebook computer 46 may include software to derive a simulated ride from actual ride data acquired from computer 28. The notebook computer 46 may also include software for post-ride analysis. Conventional post-ride analysis tools have allowed cyclists or other users to define intervals within a ride, compare power and other biometric information between intervals, and generate associated reports, charts, graphs, and the like. The present invention improves upon such tools by allowing the integration of gradient information into the analysis.

Specifically, in conventional post-ride analysis tools, a map similar to the gradient map 50 may be displayed as a power measurement map or timeline. That is, the power measurements made be processed to show, as a function of time, the changes in power during the course of the ride, or selected interval. Heretofore, as noted above, the changes in power did not account for changes in elevation on the cyclist's applied power.

Gradient map 50, on the other hand, does provide such differentiation. Specifically, the gradient map 50 graphically illustrates the gradient changes encountered during the course of a ride, or interval thereof. Using known user interactive tools, a user can interact with the gradient map 50 to gleam additional information. For example, the user can interactively define gradient intervals, such as X₁ to X₂ or x₃ to X₄. Alternatively, the software of the computer 46 could automatically identify gradient intervals. For a selected interval, the user can then instruct information associated with that interval to be displayed, including: gradient value, interval time length, traveled distance during the interval, max or average power in the interval, average or max speed during the interval, max or average heart rate during the interval, and the like. Specifically, those values that can be provided for the ride as a whole can be derived and displayed for a selected interval. Moreover, the data associated with particular gradients can be compared. For instance, in the representative gradient map 50, the gradient of interval X_START to X₁ is visibly similar to the gradient of interval x₂ to X₃. Thus, the user can quickly identify the gradients and then interact with the gradient map to display the measurements and derived data associated with the gradients for comparative analysis. In conventional post-ride analysis tool, it would be arduous for a user to identify portions of a ride having similar gradients and then rnrrmnre hinm^ptric and other data associated therewith.

12 This system of determining elevation or gradient or elevation changes using power measurements is believed to be highly effective for larger gradient changes, particularly when speed is reduced on an uphill gradient. It is also believed that this system of determining elevation or gradient changes will be effective where small input power is required at larger speeds, e.g. when going down a larger gradient. Since relatively slow and subtle gradient changes over longer distances may be hard to distinguish based on certain sources of error, which may be, e.g. aerodynamic drag and environmental wind conditions, the present invention contemplates that the computer 28 (or notebook computer 46) may store modifying or scalar values to account for drag and environmental sources.

Figure 5 shows power, in watts, as a function of speed for two rides that are identical in all respects except for aerodynamic drag. As shown, differences is aerodynamic drag are more pronounced at points of higher speed and greater power. In the representative chart, the power- speed curves or trend lines effectively converge at a speed of approximately 20 MPH, which indicates that error sources of this type decrease in significance at lower speeds. Thus, for power measurements taken at angular velocities in excess of 20 MPH or other speed value, the power measurements may be scaled to account for aerodynamic drag, environmental wind conditions, and the like, so that such factors or sources of error are considered during in-ride and/or post-ride analysis as well as ride simulation.

As described above, computer 28 is provided to acquire and display information associated with a ride, or portion thereof. The computer 28 is also designed to communicate with a general purpose computer, such as notebook computer 46, which may have software programs to assist with post-ride analysis and fashion simulated rides that can be input to an electronic resistance unit of a simulation device.

An exemplary computer 28 is shown in FIG. 6. The computer 28 is contained within a relatively thin and lightweight housing 52 that seals the computer 28 and associated circuitry from weather, dust, dirt, and the like. In a preferred embodiment, the housing 52 is made up of a hard, yet

HσVitw^piσVit n1a<^;tic material, as known in the art. The computer 52 is powered by a battery (not

13 shown), which in one embodiment, may be a rechargeable battery. In this regard, it is contemplated that the housing 52 may support power connectors (not shown) that couple to contactors of a battery charger (not shown) that provides charging power to the battery, as known in the art.

The housing 52 has a faceplate 54 with a display 56 mounted thereto as well as a user interface 58 composed of a pair of control buttons 60, 62 which allow a cyclist to control the information that is shown on display 56. For example, the control buttons 60, 62 allow the cyclist to toggle through the various performance values acquired or calculated by the computer 28, such as current power, max power, average power, current speed, max speed, average speed, torque, distance traveled, trip time, time of day, cadence, average cadence, energy expenditure, total distance, current heart rate, max heart rate, average heart rate, time in target heart rate zone, calories burned, calories burned per hour, and the like. The control buttons 60, 62 also allow the cyclist to program certain programmable parameters, such as cyclist age and weight, which may be used by the computer 28 to derive performance metrics.

If integrated with a GPS or similar navigational receiver, the display 56 can also provide a mapping of a traveled or to-be traveled route. The computer housing 52 may also support additional control buttons, such as an illumination button (not shown) to illuminate the display 56, such as through backlighting, to improve visibility of the display 56 and its contents, when desired.

The computer 28 may also include I/O connectors (not shown) such as USB ports to facilitate the downloading of data from or uploading of data to a general purpose computer, such as notebook computer 46, using a USB or similar cable (not shown). It is also contemplated that the power supply of the notebook computer 46 may be used to charge the battery of the computer 28 when connected to the notebook computer 46 via the USB cable, in a manner known in the art. Rather than cable-based data transmission, the computer 28 may include circuitry to enable the wireless transmission of data to the notebook computer 46 if equipped to receive wireless communications.

14 Referring again to FIG. 1 , in a further embodiment, an accelerometer 64 may be mounted to the bicycle 10, and in one embodiment, to the computer 28. The accelerometer 64 provides three-dimensional orientation information that could be processed by the computer 28, or notebook computer 46, to calibrate derived gradient information. Specifically, the accelerometer 64 may detect titling the bicycle 10 and provide that information for inclusion in gradient derivations. For example, is recognized that in some instances, a cyclist may take action on the bicycle that slows the wheel speed, e.g., breaking, without decreasing the applied power, e.g., pedaling briefly while brake is applied. To avoid this being recognized as a change in gradient condition, the output of the accelerometer 64 may be correlated with the presumed change in gradient to determine if the bicycle 10 responded to such a gradient change. If the bicycle 10 had experienced a gradient the change, the accelerometer 64 would detect a tilting, either forward or back, of the bicycle 10 and provide such information for calibrating the gradient information.

The present invention has been described in terms of the preferred embodiment, and it is recognized that equivalents, alternatives, and modifications, aside from those expressly stated, are possible and within the scope of the appending claims.

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Claims

CLAIMS What is claimed is:

1. A method for providing for providing performance information to an operator of a human powered wheeled device, the method comprising: acquiring values for a set of performance parameters during human operation of the wheeled device by a cyclist having a weight from a first position to a second position, wherein the performance parameters are associated with an effort used to ride the wheeled device from the first position to the second position; and determining a gradient between the first position and the second position from the values for the set of performance parameters.

2. The method of claim 1 wherein the set of performance parameters include angular velocity of a driven wheel of the wheeled device, applied torque to the driven wheel, and time spent moving the wheeled device between the first position and the second position.

3. The method of claim 2 wherein determining the gradient includes: determining a first applied power at the first position and a second applied power at the second position; determining a difference between the first applied power and the second applied power; determining a product of the difference and the time spent moving the wheeled device between the first position and the second position; and multiplying the product times a rolling resistance value, one-half of the weight the cyclist, square of an angular velocity value, and a gravity value.

4. The method of claim 1 further comprising providing the gradient to a computer that fashions a simulation of the ride that includes the gradient from the first position to the second position.

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5. The method of claim 1 further comprising scaling the gradient based on bicycle speed to account for drag during the ride from the first position to the second position.

6. The method of claim 1 further comprising displaying a graphical representation of the gradient from the first position to the second position.

7. The method of claim 6 further comprising displaying values for the performance parameters with the graphical representation of the gradient from the first position to the second position.

8. A ride analysis apparatus comprising: a power measurement system that measures applied power to a wheeled device during movement of the wheeled device along a surface during a ride; and a computer linked to the power measurement device that determines elevation changes encountered during the ride from at least the applied power.

9. The apparatus of claim 8 wherein the computer is mounted to the wheeled device.

10. The apparatus of claim 9 wherein the computer is a general purpose computer remote from the power measurement system.

11. The apparatus of claim 10 wherein the computer includes a stored program that causes the computer to develop a simulated ride based on measurements taken by the power measurement system during the ride and the elevation changes, and inputs data for the simulated ride to a simulation device that provides a stationary simulation of the ride.

12. The apparatus of claim 8 wherein the computer includes a display and a stored program that causes the computer to generate a gradient map of the elevation changes and output the gradient map on the display.

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13. The apparatus of claim 12 wherein the computer further includes a stored program that causes the computer to detect operator interaction with the gradient map and further causes the computer to determine performance metrics and a value of the elevation change for a selected interval of the gradient map and output the performance metrics and the value of elevation change for the selected interval on the display.

14. The apparatus of claim 8 wherein the power measurement system measures applied power from applied torque to and angular velocity of a driven wheel of the wheeled device, and wherein the power measurement system measures applied power intermittently.

15. The apparatus of claim 14 wherein the power measurement system determines a speed of the wheeled device at each measurement of applied power and if the speed exceeds a pre-defined threshold value, calibrates the applied power measurement to account for drag on the wheeled device.

16. The apparatus of claim 8 further comprising an accelerometer that measures position changes of the wheeled device during the ride.

17. The apparatus of claim 8 wherein the wheeled device is a bicycle.

18. A system for determining elevation changes in a human-powered device that is advanced along a surface, comprising: power sensing means for sensing power applied by a user to cause movement of the device over the surface; and means for calculating variations in elevation during advancement of the device over the surface using measurements of power applied by the user to advance the device over the surface.

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