Originally Posted by 2new2this

What RPM are you spinning at? This guys seems to want to ride in the 35 MPH range, and I dont know too many people that can ride that with 70 G.I.

I don't know what my RPM is? Is there some kind of formula to figure that out? I recently maxed out at 32.6 mph on a decent little hill... I don't know what G.I. is either...

It should be 130mm BCD or 144 mm BCD. Once you find that out you can decide which chain rings will fit.