Originally Posted by
Velo Vol
Shimano 6600.
For a while the back one has done this weird thing were sometimes it does not want to shift to smaller gears on cooler rides. Then on warmer days it works fine. I don't get it.
My 6600 bike has done that on both shifters. I don't ride it very often and I have tried WD-40 but it gets gummy in there after the bike sits in cooler weather. The last time I used silicone spray lube and the shifters worked great after that. Turn the bike upside down and spray into the shifter at the base of the lever.