Gear ratio does 52-16 really equal 39-12

mickisup

According to the metric gear roll out charts a standard 700x23 wheel with a maxiumum gear of 52-16 or 39-12 will both roll 6.94m - youth A gear restriction if racing.

However can anyone confirm whether there are differences in the output that can be derived from each combination, i.e. does the 52-16 have 'mechanical' advantages over the 39-12 even if the rollout figure is equal.

Thanks

TommyEss

12 tooth sprocket will wear a bit quicker than a 16.

keef66

39-12 involves more cross-chaining, but mechanically they are identical. If you rode them both blindfold you wouldn't be able to tell which was which (but you'd probably crash)

dennisn

mickisup wrote:

According to the metric gear roll out charts a standard 700x23 wheel with a maxiumum gear of 52-16 or 39-12 will both roll 6.94m - youth A gear restriction if racing.

However can anyone confirm whether there are differences in the output that can be derived from each combination, i.e. does the 52-16 have 'mechanical' advantages over the 39-12 even if the rollout figure is equal.

Thanks

I would guess that the 52-16 would have a very, very, very, very, slight advantage in "smoothness"(if you will) due to the chain not have to flex and unflex quite so far.
Would you notice it?
I think you should get the "Grasping at straws" award of the decade.

slowbike

Have a read of this:
http://cyclingtips.com.au/2010/04/the-b ... advantage/

I've always felt that big ring, larger sprocket was faster than small ring, smaller sprocket - not by anything significant though.