Originally Posted by
HillRider
That's a big qualifier. Many riders (me, for example) using triple road cranks will change the factory 30T granny chainring for a 26 or even 24T. That change will usually exceed the derailleur's published wrap capacity so using small-small may leave the chain too short to cover the absolutely essential big-big.
Good point.
There's also this: One generally only uses the granny chainring combined with the largest 2 or 3 rear cogs for grinding up steep hills. Consequently many riders never use their derailleurs full slack take up capability. Also, if the chain does go a little slack in the little/little, what's the worst that's likely to happen?
If I'm going to err, I want a chain that's a little too long rather than a little too short.