Originally Posted by
DrIsotope
A 42T is an excellent choice-- paired with an 11-42 cassette, you can climb just about any hill you would come across, and the 42-11 spins out around 30mph.
I would quibble a bit with that. A 42-11 does not "spin out" at 30mph - that's only about 100rpm.
p.s. I don't see it as progress to go from 15% jumps on a 5 speed freewheel with double chainrings (30+ years ago) to a 15% jump on a 10 speed cassette with a single chainring.