Oscillating rear sprocket

Vatte

Vatte

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Dec 4, 2021
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Germany
What could be the reason for an oscillating rear sprocket? It looks like the sprocket carrier is oscillating.
The sprocket is flat and I already mounted new damper rubbers. Rotating the sprocket carrier made no difference, also.

What else should I check?

YouTube short clip

Thanks in advance
 
Last edited:
Measured exactly the same on both sides. If the axle isn't aligned I'm sure there wouldn't be an oscillating movement instead it would just run crooked.
 
The sprocket looks fine. The oscillating movement seems to come from the sprocket carrier.
 
Vatte said:
The sprocket looks fine. The oscillating movement seems to come from the sprocket carrier.
Click to expand...
You sure the sprocket carrier is pushed all the way on and the rubbers cushions are all on all the way?

All the spacers are in? The sprockets i completely flat and mounted properly...I mean if yes, to all that, then it gotta be the sprocket. There's not much going on there. Bearings in the carrier are in properly?


R
 
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Here is my overdue response.

I checked the sprocket and the axle to be even/flat. The spacers are all there and mounted correctly.
Then I bought a new sprocket carrier bearing. While fitting it I had to find out, that the bearing seat inside the sprocket carrier is worn out.
The old and even the new bearing has ~1 mm clearance in the seat.
So I had no choice but to use a new sprocket carrier, apart from center punching the bearing seat and glue the bearing into the seat with Loctite 638 or 620.
With the new sprocket carrier and the old sprocket there longer any sign of this oscillation.

Root cause identified and problem fixed.
 
Good post.
How exactly did "see" the oscillation?
I mean, when you pull/push on the sprocket did it move... or was it not until you took the carrier off that the movement was visible?
 
The oscillation was visible while rotating the rear wheel on a paddock stand. (see video in first post)
With fitted rear wheel the sprocket was not movable by hand but with the sprocket carrier dissembled I was able to push the bearing with axial clearance between the edge of the bearing seat and the circlip. The bearing did not fall out even after removing the circlip because right behind the circlip groove there is a lip which was not worn out.
 
Letting the bike run on the stand 🙈🙈🙈

No way I am gonna try that... did you notice initially while lubing the chain or something?
 
Yes I noticed it initially while lubing the chain. That's why I wrote rotating the wheel. How, by hand, by engine, etc. is up to you. ;)
 
I went to install my 5-spokes wheels today and had to change plans...

Once I cleaned the debris off the sprocket carrier I found that the bearing has at least 2mm of radial play in the carrier.

...so the laced wheels went back on.
 
So after further investigation, the bearing has an obviously bad spot which wants to lock-up every few rotations; guessing that's what caused it the rest of pieces to get worn.

Check out the wear groove on the split ring:

20240818_133157.jpg
 
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