I swapped-out my crankset over the weekend, triple to double (105 brifters), and now have a problem shifting from the big to small ring. I set the high and low limits, height, rotation etc. and that all appears to be OK. It shifts from the small to big ring without issue, but when shifting to the small ring, extreme pressure must be applied to the shift lever before the der will move. When it finally does shift, it's accompanied by an abrupt "pop", instead of a "click". A few times the brifter actually felt like it was bound-up and the lever would not move at all. After pushing both levers to and fro, it would finally respond. I fear I may actually snap the lever off, it takes so much force. I adjusted the cable tension so it's as loose as possible, while still being able to shift to the big ring adequately. I'm not sure how to proceed. Any suggestions would be greatly appreciated.
I don't know. Did you replace the bottom bracket with the correct type for the double?
It does sound as if the cable tension is too high, have you checked the routing to make sure nothing is binding on the cable?
Have you checked the shifter end of the cable to see if it is fully seated?
Sorry, but this isn't making sense. The only force involved in a shift from large chainring to small comes from the spring of the derailleur. So applying force to a shifter lever should be completely fruitless, and any effect perceived might just be coincidence.
From the fact that it "pops" when it does release, I'd guess that the shifter is releasing cable as it should, but something's binding on the cable between there and the derailleur. A crimp in the housing would be a likely suspect. Or maybe one or more strands of the cable has broken or started unravelling inside the housing. If you disconnect the cable from the derailleur, does it seem to slide smoothly in both directions?
It may not make sense, but that's why I'm asking. With cable disconnected, the der does move from side to side smoothly. If I understand the shifter correctly, it feels like the ratcheting mechanism is jamming. I'm putting force on the paddle because that's what's needed to get any response. I'll check the shifter tonight to make sure the cable end is seated etc.. There don't appear to be any interferences in the cable routing. Thanks for the responses. (I did install a bottom bracket for a double.)