Originally Posted by ollyisk
all i know is that it creates a very small difference in your gain ratio. the difference is extremely slight and i don't think you'd notice much of a difference.
it changes your ratio not one bit. that is dictated by
the gears. a longer crank will let you produce more torque and possibly have an easier time turning a large ratio at slower speeds. but the trade off is having to move through a bigger circle (possibly more slowly).
i like 175's, and i notice a difference over 170's. i have one of each on my two bikes now, and im hunting around to get 175's on the campus bike so they will both be the same again.