Originally Posted by
Nagrom_
Absolutely not.
If I am pedaling 170's at 150 rpm's, this is a circumferential velocity of ~160,221mm/minute.
Let's call this speed "My maximum ability."
This exact velocity on 165's translates to ~155 rpm.
These RPM's on a 52x16 gear ratio, at 85.7 GI's would result is speeds of 39.5mph on 165's, and 38.3mph on 170's.
These difference would increase with higher cadences as well, i.e. 240 rpm on 170's results in ~250 rpm on 165's
It definitely isn't negligible.
Lets see. Even using your numbers, your 170mm max. is 150rpm and your 165mm max. is 155. Thats roughly a 3% difference. Sounds pretty negligible to me.
More to the point though, in the real world your maximum cadence potential is limited by your ability to controllably move your legs in a circle, and no one that I know can maintain a controlled spin at 240-250rpms, so even though your numbers look good on paper, in the real world they are totally meaningless. Get up on a set of rollers with both cranksets and see what the difference between your maximum cadence rates are for each length crank. The results will be negligible.