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Hi there, every time I'm cycling up a hill I have this question in my head and I'll not be able to concentrate until I've worked it out so here goes 🙂
If I'm in a choice of gears so that for each turn of the pedals I travel one metre, and then change to a larger front gear and a larger back gear (or indeed smaller and smaller), so that I still travel one metre for each turn of the pedals, is there any difference at all to the energy transfer from pedals to back wheel? (ignoring the angle of the chain)
i.e. does one combination use less torque/turning strength at the crank than the other, even though the overall distance travelled is the same?
Apologies if this makes no sense, only I did chemistry instead of physics at school.
Cheers,
Tony
you might get tiny difference in efficiency - iirc larger sprockets are more efficient - but 32 / 32 or 22 / 22 - the gearing and effort required is the same
there may be a slight additional loss with two big rings due to friction but, to all intents and purposes, the same gearing uses the same energy.
i try not to think about gear ratios when im climbing
i sing, i take in the view, i count in threes, i remind myself to breathe.........
Well that was fast, thank you - I can sleep soundly at work this afternoon now. 🙂
TJ is correct.
Shimano commissioned research on this about a decade ago.
It was titled ' Effects of frictional loss on bicycle drivetrain efficiency' and was published in 'Transactions of ASME', Vol 123, 2001.
Larger sprockets provide better efficiency at higher power loadings for a given ratio, so 32+32 is better than 22+22.
Actual improvement is only a few percent.
Chainline and lubricant was far less significant than the smallest sprocket effect.
Seems bending the chain through high angles causes high (percentage) losses, particularly at low speed and power values.
The extreme spread of efficiency found in the research showed 80 to 99%, so it can be a significant factor.
PaulD