Lower jockey wheel skipping on chain

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snailmale
Posts: 10
Joined: Wed Apr 09, 2014 1:10 pm

by snailmale

Hi there,

My lower jockey wheel (aluminium) is skipping on the chain when I run low gears (39-28). It meshes nicely with the outer link of the chain since it is wider, but makes the chain jump a little to the side in order to fit into the inner link. This basically means that the jockey wheel is further inboard (toward the wheel) than the chain when running low gears. There is also noticeably more noise when running on the low gears than high gears, due to the chain rubbing on the jockey wheel. The derailleur itself does not move due to the skipping, but when turning the crank at a very low speed (or moving the chain by hand), I can see the chain shifting sideways slightly to accommodate the jockey wheel when it reaches the narrower chain link.

I have aligned by Low derailleur screw as far outboard, away from the wheel, as possible, to the point just before the chain wants to skip to the 2nd gear. However, the issue has persisted.

Running a Token tiramic jockey wheel on Shimano 105 5700 drive train. I noticed this issue before, but just figured it was normal as my gears shift smoothly. Then I had a chain break, twist and jam inside the jockey wheel cage on Sunday, and I'm kind of paranoid now. After fitting the new chain, I took it in to the bike shop nearby and the mechanic rode the bike up and down a small hill and said that everything seemed A-okay, shifting well. He suggested that I don't waste money by sending it in for a full tuneup.

My guess now is that it is due to a slightly bent derailleur hanger. I'm not fussed by the noise, but do worry that my chain will experience wear and break easily. Should I send it in for straightening, or just ride on? Anyone with advice/experience on this? Thanks!

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veloflyte
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by veloflyte

It is most likely because the pulley cage is not perfectly aligned with the chainwheel. You can bend the pulley cage a bit to put it in a better alignment. I've done it hundreds of times over the years when I was a bicycle mechanic at the Wheelsmith.

Of course you won't be able to do this if you have a carbon fiber pulley cage.

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bikerjulio
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by bikerjulio

I'm thinking @velo has the most likely answer. ie cage is bent. Sometimes it's easier to remove the RD to eyeball alignment of the pulleys.

2nd thing is as you have already raised - the hanger. And it's true to say that a lot of hangers are not straight.

It needs to be checked with the proper tool. My only caution here is that some hangers don't take well to "adjustment". The metal is often a brittle alloy that can be weakened by the process.
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bura
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by bura

I would check the hanger and the cage .
The hanger has to be checked very carefully .If there is a slight bend in it I would not use it any further. It may be fine for another 1000kms or more but
due permanent stress cracks can occur in the alloy and all of the sudden you will have a rear derailleur jam bending the rd into the rear wheel which is not good for your health and resulting damage will cost you more than just a new hanger.
If the hanger is aligned perfectly which can be measured very easily (check youtube) then you should check the 105's alloy cage if its bent.
I would dismount the cage to bend it back to its original position.
If there is still some pulley centering needed after all bending and rd adjustment for sure you can center both pulleys different in your cage by using washers if only one pulley needs to be centered some different than the other.
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wpccrunner
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Location: CO

by wpccrunner

reviving an old thread as i am having the same issue. just replaced the pulleys on my rear derailleru after the stock ones had seen enough mileage. the lower pulley does not mesh nicely with the chain when in the top (easiest) 3 gearsand the result is worse when in the big ring (cross chained). I did not have any issues with the stock pulleys. The pulley wheel hits the inner side of the narrow links and has to "click"into placeas you pedal. it creates a very loud noise and does not seem sutible for any bit of power.

Setup is a sram red 10 speed RD (i believe the 2012 version when it was redesigned just beore going to 11 speed)
Hawk racing SRAM pulleys (with supplied bushing installed in upper pulley)
Ultegra 6700 Chain and 11-28 cassette
FSA SLK Crank with Praxis 52/36 chainrings
402mm chainstays
I do not believe the derailleur cage is bent since it is carbon it would likely snap before deforming.

any thoughts? i have reached out to HAWK racing and awaitng response

adilosnave
Posts: 159
Joined: Sat Dec 23, 2017 2:10 pm

by adilosnave

Is it possible the chain is slightly stretched out? This would then change the distance that the pulley teeth engage. Don't know but possible. I was surprised at how loud my derailleur had become after using the same chain on the trainer this winter only to find it had stretched out quite a bit. Maybe close to half a link.

alcatraz
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by alcatraz

Set proper skewer tension and remember it, always use the same to preserve consistent hanger alignment. Then check hanger alignment.

Check for play in the derailleur cage (red is not famous for longevity)

If you have a deteriorating derailleur and want to try and squeeze out more kms, then you need to eyeball the alignment.

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wpccrunner
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Location: CO

by wpccrunner

chain's new, only has 8 miles.
hanger adjust with parktool DAG
doesnt seem to be excessive play in cage
almost looks like the pulley is offset in the cage causing the issue.

TobinHatesYou
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by TobinHatesYou

Some pulleys have profiled teeth (slightly bladed on the leading edge.) Could the lower pulley be installed backward by accident?

2lo8
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by 2lo8

It's probably the chamfered tooth thing. The bottom one should have chamfered teeth for eactly this reason on the originals. Many of the aaftermarket ones don't.
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wpccrunner
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by wpccrunner

yes that is what i have noticed from comparing to my other bikes. the Hawk racing pulleys do no have the chamfer on the leading edge and may be the downfall of this setup. Have resorted to puchasing some new stock SRAM pulleys to install and see ow they play. Still waiting on a reply from Hawk with some thoughts...

The pulleys did work a bit better on my other bike with 10 speed rival setup so if they chamfer is the issue on my Red bike they will go on teh rival. quite a shame as the price is good and the friction facts lab data is excellent for those hawk pulleys. seems as though they need some work on the teeth design. Maybe ill just invest in a dremel

bikehaus
Posts: 14
Joined: Fri Apr 01, 2016 12:47 pm

by bikehaus

Hello,

I just swapped a new Dura Ace/XTR chain onto my Di2 system because the old one was stretched. The lower pully arm and wheel skip *forward* towards the front of the bike every few seconds. This doesn't appear to be a chain skipping left/right. Any ideas?

TobinHatesYou
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by TobinHatesYou

bikehaus wrote:
Fri Jun 05, 2020 11:50 am
Hello,

I just swapped a new Dura Ace/XTR chain onto my Di2 system because the old one was stretched. The lower pully arm and wheel skip *forward* towards the front of the bike every few seconds. This doesn't appear to be a chain skipping left/right. Any ideas?

You might have routed the the chain through the derailleur cage incorrectly.

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alcatraz
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Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

How big is the skip? Just a tiny vibration in the crank, once per chain revolution? Bad quicklink?

New chains work badly with worn cassettes. If you roll the chain slowly off the cassette (hold rear wheel with one hand, and crank with the other) you can see if it moves around on the teeth as it rolls off.

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