Need to replace knurled bearing on Schlumpf

Just finished a 26km ride today when right in the final k I heard some strange noise from my hub while riding in low gear. After switching to high gear and finishing the ride I took a look at the hub and it seems the bearings have come loose from the hub on the knurled side. My hub is an early one being a M122.

How difficult is to replace the knurled bearing?

Sorry to hear about this.

Does this help at all?

This is of a 400 series hub but should help a bit.

If you can clean the hub up and take closer pictures it might help.

Do you have a retaining clip?

I think the video is for the other side - not seen anyone talking about DIY stuff for the knurled bearing side, and only remember seeing people talking about ordering it from / returning it to Florian, sadly.

I know @jaco_flans csn work on these hubs, but I’m still guessing that the bearing needs to come from the manufacture still though.
Don’t own a schlumpf unfortunately

I did view that video yesterday and I thought it’d be a simple job but I’ve been scouring previous threads and since it’s the knurled side it’s going to be a lot more complicated then I thought. I’ll try and remove the crank arm later and have a better look but the bearing definitely needs to be replaced.

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Most of the bearings are custom for Schlumpf. I do have some in stock though, I’d have to confirm which one.

The bearings on the Knurled side are the same as the other side, it’s not the bearing itself that is knurled.


Found someone that was able to pull apart the hub for me and he’s found that left inner bearing is sized 22 x 37 x 9mm (ID, OD, width. However he has mentioned some problems with the right inner bearing too.

“The outer bearing on the right side is also failed - the inner race has split in 2. The rubber seals are still intact, and they bear the part number 6904-RS, that references to a 20x37x9mm bearing. This won’t fit as the shaft it runs on is 22mm diameter. I wonder if Florian had these bearing specially modified. The big outer bearing on this side feels pretty rough too.”

This is likely of little help but I did once ask for prices from Florian for spare bearing for my S00019 hub

This was the response. No direct idea if these helps you or the person helping you but it sounds like one bearing size is no longer made and has to be resized.


  • 2x d62 (CHF 40.- each)

  • 3x d39 (CHF 32.- each)

  • 2x d32 (CHF 24.- each) ?

In the beginning we used an outer diameter of 38 instead of 39, but these bearings are no longer available. The part has to be turned to d39 if replacement is needed.

You can sometimes find modified bearings like this if you search “6904-22 2RS” (or any other combination of the designation of the standard bearing with the modified dimension).

Not sure how much use a German seller is for you, but a bearing specialist near you may have those, as it’s seems a few bike manufacturers also use that size.


Thanks for that information, it’s helped my friend track down some local suppliers. I’ll be checking them out in a couple of days so fingers crossed it works out


Good to hear it’s looking hopeful.
Does anyone have a list of the specs of the user-accessible bearings for the different generations of hub? Since most of the bearings can be accessed with just the removal of a circlip and a bit of gentle pulling, we can potentially replace damaged ones as well as servicing them. I’ve cleaned out and repacked all the bearings I could reach that way on the non-knurled side of my hub, but the biggest bearing there is still sounding rough, and although I’ve found a supplier with one that looks right, I’d like to be sure of the correct spec before spending the money.

Ended up ordering the following from from a local supplier

2x Bearing MR 22379 ABEC 3 22x37x9
2x Bearing 6808-2RS Single Row Metric

I have since retrieved my guni and it’s functional. Took it for a test ride this morning and changed gears up/down and seemed to handle ok. It does feel different to before I guess it’s because it has 4 new bearings. Will have a couple more rides this week to see how I go but I’m confident that’s it’s fixed.