Been trying to get it shifting properly for hours and hours to no avail. I can get it to upshift well, but no matter how I adjust it, my 12 speed XT/XTR groupset refuses to shift down on the cassette smoothly and quickly. I even put on a brand new cable/cable housing. At this point, do I need to check my hangar alignment, or is my derailleur somehow bent?
Can't get my Shimano 12 speed to downshift properly
byu/anarmyofants inbikewrench
by anarmyofants
7 Comments
Hard without seeing the derailleur in the picture. Alignment is always the first thing you should check for a bad shift, then adjust your high limit, cable tension, low limit, and b limit. Park tool as a great video. Also maybe try adjusting without the clutch engaged. The clutch requires some torque on the chain to help the shift.
How does it downshift if you turn the clutch on, take it off the stand and give it a quick spin around the block?
Clutched derailleurs are often far happier in actual use with proper force through the pedals and resistance from the ground than they are on the work stand.
Check B-screw and hangar alignment.
https://preview.redd.it/l9f8cprqp9ff1.jpeg?width=2160&format=pjpg&auto=webp&s=2abcfdd9b56edd14e6ae5f460cc46efa955f2cef
Get a rear derailleur hanger alignment tool
Check that the shift cable is not dragging and that the derraileur is clean and properly lubricated.
Bent hanger. I literally just had the exact same issue. Borrowed my old man’s hanger alignment tool and it was pretty bent. Spent 15 mins re aligning it and now she shifts like an absolute dream and it took me 5 mins to dial it in LOL
Possibly too much cable tension… it can be a fine balance to hit the sweet soot of up and down both shifting well.