Trek recently released a belt driven bicycle (instead of chain drive) which led to a discussion among some cycling friends. Which led to discussion of torque, power output, etc. Anyway, I'm trying to compare the chain tension of a motorcycle vs the chain tension of a bicycle. I'm better with electrical systems, my mechanical systems knowledge is rusty.(adsbygoogle = window.adsbygoogle || []).push({});

These specs are from a real motorcycle:

engine makes 16 ft-lbf at 10,000 rpm

primary reduction ratio is 1.9

1st gear reduction ratio is 2.7

Final reduction ratio is 2.7

mass is 420 lbs

Based on the above:

the output shaft of the engine is 30.4 ft-lbf @ 5260 rpm

post-transmission pushes 82 ft-lbf @ 1950 rpm

at the rear wheel (in 1st gear) it's 221 ft-lbf, @ 720 rpm.

Track Bicycle:

Rider is 150lbs

Crank arms are 170mm (0.56 ft)

Gear gain ratio is 3:1 (normal for a track bike)

Mass is 20 lbs

Based on the above:

at the crank, rider makes 84 ft-lbf

at the rear wheel, 28 ft-lbf

I'm not exactly sure how to calculate chain tension from here (or perhaps I've already made a mistake...) I'm thinking that I need to specify an acceleration before I can get the answer. Can't quite recall the appropriate equations.....

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# Motorcycle vs Bicycle chain tension

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