Originally Posted by
jimbo007
I max out at 12-15 mph on a flat street. It seems two more high gears would get me up to 20 mph. I could loose the granny gear and not worry too much. I would like to change the cassette to a 9 speed and see how it works. What else needs to be changed?
Using Sheldon's
gear calculator, you should be able to hit a max speed of 22.3 mph @ 80 rpm.* It could be your equipment, but I suspect if you swap out to a taller gear... you still won't be as fast as you want without working harder for it.
* I used wheel size of 700x38, crank arm length of 170mm, and your highest gear combo of 48x14.
I just double checked my own stats (26"x1.5, 170, 42x11 and 80 rpms. I come out at 22.6 mph. I'm very close to hitting that at a constant when I put out the effort, but no way can I actually hit the max speed of 33.9 mph, which would require 120 rpms.