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enter image description here

Recently my rear wheel locked up while going downhill, the lockup caused the damage in the foto(scoring in the aluminum frame by the axle) is it bad?

The bearing is of course destroyed.


Yes, it is the rear dropout (where the wheel sits against the frame.)

Photo shows the right-hand side where gears are, but both sides have the same damage.

It happened when one of the rear hub bearings exploded for some reason and the rear hub became seized, locking the rear wheel and moving the whole hub assembly up against the frame.

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    This is a view of the right-side rear dropout, viewed from below the left-side dropout, but the bike is rotated back on itself? So that thing to the left is your derailleur hanger? I'm having problems getting oriented.
    – Criggie
    Commented Feb 20, 2023 at 23:28
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    Damage? Could you perhaps drop a circle on the damaged are you concerned about?
    – Hursey
    Commented Feb 21, 2023 at 0:49
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    Is the hanger bent? It looks replaceable. What make/model of bike?
    – mattnz
    Commented Feb 22, 2023 at 4:08
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    A photo of the through axle as well might be useful.
    – Criggie
    Commented Feb 22, 2023 at 7:23
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    Please tell us which hub it was. Maybe include a photo. We cannot understand how this damage happened. This is necessarily however to evaluate the damage we see here.
    – gschenk
    Commented Feb 22, 2023 at 9:00

2 Answers 2

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Although more photos of the frame would help, from what I see you've got some cosmetic damage, but nothing I would be particularily concerned with as far as past damage goes.

If you want to be extra safe, you can take the frame to a repair shop where it will be face-cut or welded for material deposition and then cut. However, I doubt it needs that. All components (bike included) are design to work within a certain tolerance range anyway.

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enter image description here

I see 5 spots of damage.

  1. Two small parallel scratches in the paint. Possibly from the chain being dragged - this looks minor.
  2. Damage to the lip - this looks like where the hub dragged over and tore off paint and exposed steel. Aluminium generally doesn't hold threads well, and the rear wheel TA thread is a high-load spot. The steel looks okay, I suspect this is cosmetic too.
  3. Hanger dangle angle. This gap looks wrong. I am unfamiliar with your bike, but its unlikely to have such a gap here. I bet it was much closer to the frame before. You may need to replace the hanger, else shifting could be affected.
    It is possible to slightly unbend aluminium hangers, but go too far and they suddenly snap.
  4. This seating area looks a bit damaged. This is where the inner race of the bearing will touch the frame directly or through the hub's endcaps, so if the hub dragged past here it may be scored. Rub it with your finger and feel for lumps which will cause the bearing to sit crooked. It might clean up with a file, but a mechanic might use an endmill to achieve a flat surface here. This part is likely not replaceable.
  5. Threads - I can't see then well but they appear to be flattened off. If the axle was torn out of here the threads would have been more damaged. This looks like the axle has been loose and maybe vibrations have flattened the thread, reducing the tension and allowing it to back off.
    Threads can be "chased" with a tap, but you have to have exactly the right specs which are likely written on your through axle, or will be in the manual or specs for your bike model.

What I can't understand is how the wheel/hub managed to move at all. You have a through-axle which is a strong bolt threaded into the drive side. It would have to break the axle, or be so loose as to fall out. The damaged threads suggest it might not have been torqued up to spec and has been loose for a while?

Clearly your rear hub needs a lot of work or possibly replacement too. It may be recoverable, but you might not trust it in the future, and a replacement wheel may provide more peace of mind.

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    If the hub got somehow jammed, it is entirely possible for the hub to spin around the axle without actually damiging the threads themselves. The axle and the hub fit with a clerence, so the friction between them would actually be minimal in such a scenario.
    – Paweł
    Commented Feb 22, 2023 at 11:53

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