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So I’m cleaning my bearings and the cups and I’ve just realised one of them looks like it’s been bent inward. Is it supposed to look like this or has something happened?

this is the one that looks wrong

this is the other

  • Looks like a wear pattern to me ? What was the condition of the old ball bearings and the cone? You should replace all the balls with a new set as a bare minimimum before reassembly. Note - the balls run on the silvery strip, the innermost part of the metal is not a bearing surface and can be any shape. – Criggie Jul 28 at 1:16
  • @Criggie actually the bearings roll in the area further in. The silvery strip that you’re talking about is where a cover goes on. I’m not sure if it was on the same side but one of the cones did have slight pits in it. I have only put good bearings in and replaced the ones that were not smooth anymore. – Willdebeast Jul 28 at 9:19
  • I can't really make anything out in those photos, unfortunately. They're rather over-exposed and the critical parts are blown out to pure white. – David Richerby Jul 30 at 12:18
  • @DavidRicherby well I can tell you that the area that should be flat, like in the second picture, is instead moderately curved inwards. Hopefully that helps you to understand how it looks. – Willdebeast Jul 30 at 12:26
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Edited version of OP's photo

Expanding on my comment cos a picture is worth many words - this is the line which is the bearing surface, that the ball bearings "bear" onto.

The slightly bronze circle that is closer to the hole in the middle is important as it provides support for the critical area, but the shape doesn't really matter. Yes the inside edge looks slightly deformed, but since its not the track on which the balls roll, then its not important.

Here's a modified cutaway from figure 6

https://the-contact-patch.com/book/general/g1615-bearings

If you want to put this to the test, clean your parts and the old balls and then draw on the bearing race with whiteboard/dry-erase marker. A sharpie might work. Either way, avoid black. Reassemble your bearing completely dry of grease and spin it by hand for a couple revolutions to put witness marks into the dry marker-pen. Only need to do one side of the axle, not both cos its only a test and not for riding. Use the old balls so you don't scuff up new ones.


I think we were talking about different silver circles in comments.

The other possibility is that there is some artefact you can see directly that isn't showing in the photos. Damage like on this spalled cone may not be visible in the photo, which would be completely different.

From https://bicycles.stackexchange.com/questions/45865/dent-in-bearing-cone-try-to-get-a-new-one-or-can-i-keep-riding-like-this

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    I understand now. We were definitely both thinking of different silver circles. The picture you posted looks the same as my cone but instead the small dent is not in one place but all over the cone. – Willdebeast Jul 28 at 11:17

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