pyze-guy

I am having issues with shifting the rear derailleur.
So new frame, swapped everything over from old frame. New cables and housing. It’s a 1x10, Shimano 105 setup, chain line is good. Had no issues at all on the old frame shifting, no adjustments needed when swapping wheels.
After I shift to lowest gears, I can’t shift from 1st to 2nd, it will drop from 1to 3 on the next shift.
If I adjust cable tension to upshift 1st to 2nd its fine, then downshifting through gears 5/4/3 suffers and I need that extra nudge to get the shift to complete.
I’ve tried new chain, swapping cassettes from my winter wheel, adjusting b screw, redoing cables to make sure no sharp bends, adjusted chain line in, nothing helps.
At a loss to do next. I’ve removed everything, reset h/l screws, swore at it, pleaded.
At this point all I can think of is
1. Hanger is crooked
2. Bent derailleur cage.
I lean towards 1 as new frame and never had issues before.
Any ideas?

Andrew R Stewart 

Cable friction.

What about the cable routing is different? I hope your bike doesn't have internal routing as that will make dealing with this a lot more frustrating. Andy

oldbobcat

Why does it have to be one problem to the exclusion of all others? Remove the derailleur, align the hanger. It isn't rocket science. If you don't have the tool, take the bike to someone who does. Then disconnect the cable, reset the limit screws and test the cable for friction without the derailleur attached to the other end. You can feel it with your hands. And your limit screw setting will be more accurate without the cable making it more complicated. Just push the thing with your hand while you pedal through the gears. Jockey wheel aligns directly underneath the first cog, under the outside edge of the smallest cog. Satisfying that, attach the cable and adjust it for indexing. Finally, adjust the b-screw--looser if the jockey wheel is too close to the big cog, tighter if the shifting is too slow at the small-cog end.

wphamilton

Could the chain line be an issue here?

Andrew R Stewart 

This is a good point. However experience suggests cable friction causes this very problem often. Of course all other aspects need to be confirmed/corrected too. Just as all aspects need to be dealt with on each situation. If it was minor indexing chain rub in many cogs then hanger alignment would have been my initial thought. Andy

oldbobcat

Good to bring up, running 105 with a single chainring, although I doubt it's causing this kind of rear shifting issues.