Originally Posted by
Leinster
I'd tend to think the other way; someone who rides up 10% grades in a 39x25 is in a hurry to get up, and is probably in a hurry to get down the other side; as much as they can spin a 52x13, I'd say they'd be even happier for the higher terminal velocity of a 53x11.
By the time cadence becomes annoying using 50x13 (over 35 MPH) you go faster tucking than trying to pedal.
More importantly total time is lower and average speed higher when you exert yourself uphill (speed is almost proportional to power) but go easier on flat (approaching proportional to its cube root) and recover downhill (still approaching its cube, except that's with total power where most of it comes from gravity so your impact is less than on flat ground).