Have you checked the derailleur hanger to see if it's bent? I've seen the behavior that you're describing, and it was happening on a bike with a bent hanger.

 

No, but that was actually something I was wondering. I'll order a new one to check. The bike is a bit older and has had a few tumbles, although nothing major.

 

I'll order a new one to check.

New RD hangers can need adjustment too. Check with a RD alignment tool or straightedge.

FWIW: In my experience, hangers can be bent but if limits and cable tension are adjusted appropriately, it doesn't much matter...within reason.

 

Isn't 1cm gap a bit wide?

From Park Tool site:

SRAM designates a 6mm between the largest rear cog and the upper pulley. Use a 6mm hex wrench to help estimate this gap. Tighten the screw to pull the body back. Shimano® uses a similar adjustment to all their derailleur. Adjust so the pulley is as close as possible but without rubbing the largest cog.

 

Check the RD pivot link that attaches to the derailleur hanger and make sure it's bottomed out on the B-screw notch on the DH and not tightened without being bottomed. If that is okay, check/replace the DH.

 

Check the cable and housing. The housing cut-ends or ferrules may be a bit worn. A little lube in the housing sometimes helps too. If the cable and housing are old, new stuff can really freshen up the shifting. It's probably not the issue, but on the b-limit screw SRAM specs 6 mm between the big cog and the RD upper pulley, not 1 cm.

 

Obama

 

That's classic bent hanger symptoms. New hangers can be out of alignment as well so that's not the best test. take it to a shop and have them put an alignment tool on it....should only be a few dollars to do and it's a quick fix.

Oh, before you do that make sure your derailleur attachment bolt is tight! I've had the mech itself come loose and not realize it. Tried to get it shifting good to no avail and then found the loose connecting bolt.

 

+1 for bent hanger. Bring it to a shop and have them check it with alignment tool. Many times they can straighten it and save you from buying a hanger.

 

Always check the hanger but most likely the problem is with the cable & housing. I would replace them.

 

Barrel adjuster at shifter. Count the clicks incase that you're going wrong direction so you can return to original starting point and go other direction.

 

1x with SRAM is 15mm gap between jockey wheel and largest cog, not 6mm.

 

Yeah that's what I read. I originally had it set to that, then saw another thread where they recommended setting the B-tension while longer travel bikes were at their sag amount. I kinda split the difference and did 10mm under sag. It didn't seem to make any difference. We futzed with the barrel adjuster plenty.

I'm pretty sure by logic it's a bent hanger, because you can pretty much always make it shift OK to the lowest and highest gear by the limit screws.

I'll either drop it off at the shop after my ride this weekend to see if they can give it some love (maybe replace the cable & housing while they're at it), or suck it up and buy the tool. I need a headset race replaced and my dropper serviced, so should probably just do the shop.

 

I read an article recently that claimed a bent hanger was the most common cause of your problem but I can't find it. I just took my Dragon to my LBS last weekend as it had a bent hanger. At first the guy was going to charge me $18, he asked me if that was too much, I said it was ok but he decided it should only be $10. I already had removed the derailleur so he didn't have to mess with that. But how recently have you replaced the cable and housing?

 

I just had a similar issue and it was caused by too much of a gap from the B Tension adjustment. I have had that problem previously from a bent hanger as well.

 

Check that the spacers between the sprockets in question are at the correct thickness.
I am currently addressing this issue on one of my bikes. Couldn't figure it out on an otherwise perfectly working setup. It started when I replaced the cassette and I could not get the shifting right. So I pulled it apart, measured and discovered the discrepency. Just changed them and now working perfectly again.

Eric

 

Cable friction causes the same problem. Internal routing really doesn't help. If you still can't get it sorted try a better cable and look at the routing for tight bends.

 

For any future readers / searchers, the problem was indeed a bend derailleur hanger. The bike shop checked it, found it was bent, tried to bend it back, broke it, and put a new one on. He also said the RD cage itself is a bit out but was able to straighten it. Shifting is great now.

 

Good u find out the hanger problem.
Sometime It's posible also the B tension distant or can try out cable tension adjustment on shifter side.

 

check derailleur hanger.

 

geez, dude, read the post two above yours. Or even one above.

 

Don't listen to chazpat, he is wrong. I would check your derailleur hanger instead of reading any previous posts.

~kapow!~

 

Stop causing controversy. You're both wrong. It's the derailleur hanger. I'm a professional fortune teller of past events so I know what was going to happen even after it already has.

 

I'm still thinkin' it's the derailleur hanger.

 

I know this is an old post, but I'd recommend checking the derailleur hanger.



Thanks for the tips. Will have my RD hanger checked.

 

I'm surprised no one has mentioned checking your derailleur hanger.

 

Thanks for chiming in only 6 years after the thread was started. Excellent choice of a thread to resurrect!

 

excellent choice of picture.

 

This is an awesome zomby derailleur hanger thread.

 

What causes poor shifting in middle of range?

It's Todd. Todd causes it.