Originally Posted by
fuzzbox
Originally Posted by
ColinL
you must have found a big hill... just coast.
39x11 should get you over 30mph if you can spin >100rpm. But even 39x12 (I don't know what cassette you have) is almost 23mph @ 90rpm. So, I think you'll find the 39 is plenty on trails and you can just coast down big hills on paved roads.
Haha yea but I'm am trying to do this 24 hr race and the course has something called "the bi**hes" which is a long steep descend to a ridiculous climb and this repeats for 5 or 6 times and as you go it gets worse and worse. So if I topped out on this hill that means I'm going to top out pretty quick on the descend since on a previous bike I was using a 44x11 or 12 not exactly sure and topped out halfway down. But that means I'm going to have more climbing ... yay me!
Have you considered a road crankset? A triple would definitely work, but if a 50/34 compact is low enough for you-- remember, you can (probably) still use your MTB rear derailleur but you can't run an 11-36 cassette unless you have a long cage RD.