Knurled bearing 'markings' on Schlumpf

I have searched the forums for this exact issue and didn’t see this exact question, so apologies if it has already been covered.

I’m having my Schlumpf repaired this week and am preparing for its return to me. I noticed when I took my frame off that there were knurled / knurling “marks” (for lack of a better term … indents? etchings?)

Is this something that was scored by a machinist when the uni was put together, or did this happen naturally over time due to the knurled Schlumpf bearing? I asked the guy who I bought my wheel from, and he had his wheel assembled by a shop, and the guy who did I can’t reach.

What would y’all recommend in terms of the fork and bearing cap? During the investigation into my hub issue, I wore off some of the blue paint. I could post a photo of what my frame and cap look like now. Not terribly worn, but worn some.

Nothing to worry about. Knurled marks are good, knurled marks are your friend. No machinist put them there, they appeared naturally.

Some wear, worn off paint, knurled marks and scratches document the maturity of your Schlumpf riding. Be proud of them when you ride.


The bearing is knurled, powdercoating is soft, the knurls in the bearing dug in, no issues there. Actually, if anything, it’s the opposite, it shows that the “bearing” wasn’t slipping often.

The “knurl” marks are very good for your unicycle frame. The early schlumpf hubs had an external torque arm attached to the frame leg. Yours is of a later version that used a straight knurl (fine spline) on the bearing mount. This spline when in a properly tightened bearing holder will not move in the frame. This takes the place of the external torque arm, similar to the arm that is present on a coaster brake b#k*.

Interesting that it shows clearly how much the top bearing cap deformed during welding to no longer be circular.

Pretty hard to avoid that unless you machine it afterwards. Maybe fillet brazing would give better results since it’s lower heat?

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