Quote Originally Posted by maillotpois View Post
Be sure you don't have any "gunk" gunking up (technical term) the cable feeds under your bottom bracket. Build of up sport drink, dirt, dead worms and frog guts down there can impede shifting.
Amen to that!

Had my road bike at the LBS last fall to repair a cable that had snapped right at the shifter. When I went back 10 days later to test ride before bringing it home, couldn't shift at all. A quick inspection revealed that the cables were gummed up at the bottom bracket. Gatorade. Riding every day kept them broken loose and at least usable; sitting for 10 days allowed everything to seize up into a goopy, gloppy mess. Since then, I've switched to Teflon cables and make sure to wipe down my bottom bracket after every ride.

And, having finished a ride this spring that left my bike a writhing, wriggling mess -- worms hanging everywhere -- I can vouch for them gumming up your cables also.