My Ultegra (6510) right shifter is acting weird when it gets cold. When it's cooler out, it occasionally doesn't want to engage when I shift to an easier gear. I run a 12-23 and it usually happens on the 14-16 cogs.
For example, when I go to push the big level in to shift from 14 to 15, sometimes I feel nothing. It just moves totally to the left, but doesn't pull on the cable to move the rear der to 15. I would release the lever and try again and then it would enage and moves the rear der. This only happens when it's cooler out. It also usually happens after I down shift first, like when I go from 16 to 15 or 15 to 14 and try to shift back up to the 15 or 16.
Does anybody know what I need to do to fix this? It's really annoying, especially when I climbing. Do I need to buy a new right shifter?
I described this to my LBS and they didn't know what to do. They said the heard of it before, but don't what the cause is. Atleast I'm not the only one experiencing this.