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I gave my bike a thorough service recently by pulling it apart and cleaning/re-greasing everything. Now everything is back together and I just can't get the rear derailleur to work properly.

The H limit screw is already fully backed out and the derailleur is at its mechanical limit, but the guide pulley just doesn't move out far enough to eliminate the chain rubbing against the 2nd smallest cog.

During service the rear axle and cassette stack was removed, however I took care to measure the position of the cone nuts beforehand and they should be in the right position. The stack is also bolted together (except for the last 2 small cogs), so couldn't be a missing spacer.

What could be the cause of this?

PS: The bike was never in a crash, so I guess the hanger is not bent. In any case I have no derailleur alignment tool at hand if it were.

The model is a Simano Deore XT (2013)

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15
  • is your derailleur bent?
    – Paul H
    Commented Oct 19, 2020 at 21:51
  • I guess not, it didn't impact anything at any point. What force is required to bend the hanger? Could this also happen by accident when tightening the cable clamp?
    – user53407
    Commented Oct 19, 2020 at 21:57
  • does this bike ever get locked up? I've locked up a bike with a perfectly functional rear der. only to come out to it an hour later with bikes jammed in a both sides of it and a bent hanger as a result
    – Paul H
    Commented Oct 19, 2020 at 22:01
  • No, it's in my garage at all times when not riding.
    – user53407
    Commented Oct 19, 2020 at 22:01
  • 2
    do you have any tension on the cable?
    – Paul H
    Commented Oct 19, 2020 at 22:03

3 Answers 3

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8

Thanks for all your help, but there just can't be a solution to it when I am an idiot ;)

Somehow when setting the cable, the pinch bolt probably wasn't open fully, so I thought I was at the limit and when tightening, I must have pulled too hard on the cable so the derailleur was pulled in 1 or 2mm inwards without me noticing.

So I...

  • unclamped the cable completely
  • made it hand-tight
  • clamped it
  • put tension on it with the barrel adjuster until it started to move slightly

I am now able to reach the H limit. Well, lesson learned. At least I can install a derailleur now ;)

Thanks for all your suggestions!

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1
  • Glad you figured it out. Now go get some dirt on that bike ;)
    – Paul H
    Commented Oct 20, 2020 at 14:58
7

If aligning the hanger doesn't work, it's not a tweaked derailleur, the guide pulley isn't slopped out, and it behaves the same with zero cable tension, the fix is then to put a spacer under the RD mounting bolt. In shops this would be a 1mm M10 axle spacer, but you can improvise with whatever.

It's unusual to need to do this on aluminum bikes, so I kind of suspect it's something else, but in a pinch the spacer may be a solution of sorts anyway.

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0

Maybe there is an axle spacer missing on the drive side. Or maybe you need to move one spacer frome the non-drive side over to the drive side. Check if the wheel is centered in the frame.

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