I got a shimano hub for my front wheel and rebuilt it last November, but didn't ride much until March. Now I hear a metal on metal grating noice when riding and my best guess is that it is comming from the new hub. Doesn't happen when I just spin the wheel, only when riding and not all the time.

Took the hub apart to see what is wrong and also add more grease. When looking for damages I noticed that on one side, in the cup part, there are two metal pins. They are the two little dots at 8 o'clock on the cup. (Apologies for the image quality.) They look like how nails without heads look, except that they jut out a bit and rounded on the top.

Pins in the cup 1 Pins in the cup 2

Is this normal? Do they serve any purpose? Could they be something that was in recycled metal, assuming these are machined and not casted?

Above all, could these be causing the noise? My guess is that when the cone is pressing, the bearings can get jammed in these withoug rolling smoothly. Each pin is about 1.5mm wide and jut out about 0.5mm.

Update: Added few clear pictures.

Pins in the cup 3 Pins in the cup 4

Last time around I used white lithium grease. I took the hub apart today and on the side with the problem grease has changed to dark gray while the other side is still white. I will see if these flattern out over time and then replace the bearings. Or replace the hub altogether.

  • 1
    Photos aren't great sorry - are these pinheads on the bearing race surface? IE the circle where the bearings roll? If they're not in the bearing's area then its of little consequence.
    – Criggie
    Commented Apr 9, 2018 at 8:08
  • 1
    What's the condition of the ball bearings and the cage holding them? Specifically looking for pitting or dullness or cracks.
    – Criggie
    Commented Apr 9, 2018 at 8:09
  • Yes, these are on the bearing race surface. On the 'cup' part with a quarter circle radial cross section, more close to the bottom of the cup. In the pictures you can see the axle with threads on top right, and the gap between the axle and the cup in dark color. Bearings didn't show any scratches or wear. I have ridden about 250miles on bumpy roads.
    – Aelian
    Commented Apr 9, 2018 at 17:11
  • 2
    If they are on the actual bearing surface (that the balls roll on) they are not normal, and not good. (But first make sure they aren't bits of trash stuck on the surface.) Commented Apr 9, 2018 at 21:43
  • 1
    Yeah - try and pick the metal bits off if possible - they've come from somewhere and likely been stuck to the surface by pressure. You'll get some more use out of them, but I'd replace the balls regardless, and inspect the cones for damage. Grease well and reassemble, and hope for a decent service life because you found the problem early.
    – Criggie
    Commented Apr 10, 2018 at 0:13

1 Answer 1


Thank you for the clearer photos. From them we can clearly see that the pinheads are not in the way of the bearings as they roll around the bearing surface.

To test that, grab a single bearing and put it in the race so the visible wear band is straight down. (ie hold the hub at an angle) Then use your finger to roll the bearing back and forth around where the pinheads are, but stay on the visible wear track. If you feel the lumps as the bearing rolls over, then I'm wrong and they ARE interfering. If not, they aren't interfering.

Note I'd choose to run bare ball bearings in this hub, not a pre-assembled bearing cage.

If the marks really bug you, consider using a Dremel or some super small tool to buzz off the lump. You might be able to scratch them off with a flat screwdriver. Would be very hard to get a file onto that surface. Clean the bearing surface well to remove all metal dust once you're finished.

  • 1
    The 'pin heads' are flatter and worn out a bit compared to last time. Together with white grease turning gray and the noise, I am pretty sure these touch the bearings. I couldn't dislodge them with a box cutter. I thought of the Dremel, but was afraid I might make things worse. Thanks.
    – Aelian
    Commented Apr 22, 2018 at 18:24
  • I'd go for the dremel personally - if the hub is trash you can't make it any worse.
    – Criggie
    Commented Apr 23, 2018 at 1:16

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.