Originally Posted by Brensan
Can someone clear something up for me? I always thought that a higher bottom bracket meant a shorter seat tube. Wouldn't that mean that a trade of higher bb and longer crank would feel the same as someone with a lower bb and shorter crank (relatively) since the distance from saddle to peddle wouldn't really change? Is this totally wrong? Is a higer bb from angled stays?
So let's assume you fit yourself the same way on either bike, so:
Exposed seat post + seat tube + crank arm = max leg extension, and you're right, that would be the same on either bike if you fit yourself the same.
However, what about min leg extension:
Exposed seat Post + seat tube - crank arm = min leg extension. Obviously this is different when the crank arm length is different.
So it's really the spin that is different, longer cranks give you more leverage, shorter cranks are easier to spin. Generally people with longer legs feel more comfortable with longer cranks.