I have the Deore SLX groupo (11-34) on my 2010 Giant Anthem X0 (about 300 miles of use) and I have this puzzing problem.
When shifting from the 11 up to the 34, shifting is normally crisp, except for the middle cog (gear 20). I can hear it trying to shift up but it won't go. If I shift again, it jumps 2 gears and shifting to the 34 just fine. So I'm stumped because it's only gear 20 that hesitates.
Has anyone see this before?