Hiscox's historical mechanism collection identifies a swinging ball-bearing bicycle pedal: a pedal body free to swing about its spindle on ball bearings as the crank turns. The calculator below does not reconstruct its dimensions. It evaluates the classical basic L10 rating-life equation for user-entered ball-bearing rating, equivalent dynamic load and assumed bearing speed.
Swinging Ball-bearing Bicycle Pedal Interactive Calculator
Vary basic dynamic load rating C, equivalent dynamic bearing load P and assumed bearing speed. Results show C/P, basic L10 life and ideal hours under constant inputs.
Equation Used
- C is the manufacturer's basic dynamic load rating for the selected ball bearing.
- P is a correctly determined constant equivalent dynamic bearing load, not simply peak pedal force.
- The entered speed n is the bearing's relative rotational speed and remains constant.
- The exponent is 3 for ball bearings; reliability adjustment, lubrication, contamination, misalignment, impact, oscillation effects and wear are omitted.
Historical Pedal Arrangement
Hiscox's illustrated mechanism collection identifies a swinging ball-bearing bicycle pedal. In the source-bounded interpretation, the pedal body swings about the pedal spindle while ball bearings reduce friction between the body and spindle. The crank carries the spindle around the bottom-bracket axis while the rider's foot keeps the pedal platform in a useful orientation.
The historical plate does not establish the former article's claimed second tilt axis, angular range, ball count, hardness, clearances or modern product construction. Those unsupported details are removed.
What This Explanatory Model Is Useful For
The animation distinguishes the spindle, ball-bearing support and pedal body. The calculator demonstrates the strong cubic sensitivity of classical ball-bearing basic rating life to the ratio C/P.
It is suitable for transparent sensitivity checks only after C, equivalent dynamic load P and relative bearing speed are established from appropriate bearing data and the actual duty cycle.
Basic Ball-bearing Rating Life
For a ball bearing, the classical basic rating-life relation is:
At constant relative bearing speed n in rpm, L10h = 10^6(C/P)^3 /(60n). NTN and SKF identify L10 as a basic rating life at 90 percent reliability. It is not the life of every bearing and is not a pedal maintenance interval.
Worked Example: Entered Rating Case
For C = 1,400 N, P = 500 N and n = 80 rpm, C/P = 2.80. Basic L10 life is 21.95 million revolutions, and the constant-speed conversion is about 4,573 hours. P/C is 35.7 percent.
The result applies only to the entered equivalent dynamic load and speed. It does not predict contamination, lubrication loss, impact damage, looseness, seal wear or the service life of a particular pedal.
Model Boundary
- Historical source: identifies the swinging ball-bearing bicycle pedal as a mechanism.
- Calculated: classical basic ball-bearing L10 rating life and constant-speed hour conversion.
- Not calculated: equivalent-load factors, load spectrum, static safety, shock, oscillation, lubrication, contamination, corrosion, seals, fits, preload, misalignment, wear, pedal structure or human biomechanics.
Frequently Asked Questions
Does swinging mean a separate fore-aft tilt axis?
The historical source title and plate support a pedal swinging about its bearing-supported spindle; they do not establish the former article's added second tilt mechanism.
What does L10 mean?
It is a statistical basic rating life that 90 percent of a sufficiently large group of apparently identical bearings is expected to reach or exceed under the rating assumptions.
Is pedal force the same as P?
Not automatically. P is equivalent dynamic bearing load and must be derived for the bearing and load directions.
Why is the exponent three?
The classical basic rating-life exponent is 3 for ball bearings.
Is cadence always the bearing speed?
No. The input is relabeled assumed bearing speed; use the actual relative bearing speed for the mechanism.
Does L10 predict maintenance or service life?
No. Wear, seals, contamination, lubrication, shock and mounting can govern service life.
References
- Gardner D. Hiscox, Mechanical Movements, Powers, Devices and Appliances: historical plate and contents entry for the swinging ball-bearing bicycle pedal.
- NTN, Ball and Roller Bearings: L10 = (C/P)^3 for ball bearings and L10h = 10^6(C/P)^3/(60n).
- SKF, basic rating life: 90 percent reliability, C, equivalent dynamic load P and exponent 3 for ball bearings; service-life limitations.
- NASA/TM-2012-217445: L10 statistical meaning and ball-bearing exponent.
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