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I received a new bike with a rough front hub bearing. Turning the axle indexing is noticeable, that when slowly turning the bearing it repeatedly snaps into the same position.

It is a cup-and-cone bearing. Brinelling is the typical failure mode that leads to indexing. In Brinelling the hardened bearing balls press a spherical depression into the bearing runs. The cause is too high peak load, in this case lateral pre-load.

The bike's front quick release (QR) was unusually tight. I am used to high clamping forces. In this case I even needed a tyre lever to get a better grip to open the lever.

Are clamping forces of a QR high enough to damage hub bearings by Brinelling?

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    Have you considered doing a warranty claim? A new bike shouldn't have damage like that regardless of the cause.
    – Criggie
    Commented Feb 5, 2022 at 22:33
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    @Criggie Yes, of course. I've already sent a message to the shop.
    – gschenk
    Commented Feb 6, 2022 at 11:35
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    I wonder if in the factory, the wheel was originally tightened with an air hammer, somewhat like a car's wheel-nuts ? That could have overdone the preload, and pushed the bearings into the race leaving dents.
    – Criggie
    Commented Feb 7, 2022 at 1:37
  • is it actually brinelling? or does it only feel notched due to the tight preload of the cones? Commented Feb 14, 2022 at 22:08

3 Answers 3

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Brinelling happens when the contact stress exceeds the limit of the material. I don't believe you can achieve that alone with a too tight QR, although it sounds like your bearings are so tight that the tightness could alter the bearing lifetime in other ways. However, in cup-and-cone bearings, the QR tightness affects the hub preload. Therefore, you should adjust both the tightness of your QR and also possibly the cones of the hub if QR adjustment alone doesn't achieve the desired preload in the bearing.

If you need a tyre lever to open a QR, it's definitely too tight. They are designed to be operated by hands only.

Also when adjusting the hubs, note that you should adjust them to have very slightly loose bearings. The QR adds the final preload to the bearings.

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  • Thanks juhist, that summarises the situation quite well. However, it is not quite clear to me if: too much preload + too tight QR is enough to cause Brinelling (or other forms of indexing).
    – gschenk
    Commented Feb 6, 2022 at 16:28
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The "indexing" feel here is odd, because I don't see how a new hub could possibly be notched in the bearing surfaces. That takes a bunch of use couple with poor adjustment.

That said, every new bike's hubs need to be checked for proper adjustment. (Unless it's got cartridge bearings.)

When I build wheels, I have to adjust every hub, from cheap ones to Shimano XT. They all come too tight, sometimes incredibly so. If buying a bike from a decent store, the shop should do this, but they often don't. (I had one bike's rear go bad after about 1,000 miles b/c I had assumed they'd done their work.) These days, I assume every new wheel will need adjustment by me before riding.

As mentioned above, proper cup-cone adjustment must be slightly loose until the clamping force from the QR is applied, at which point it should have no play. A simple way to check this is mount the wheel, do the QR halfway, enough to keep it in the dropouts, and then use fingertips to try and rock the rim perpendicular to the axle. With gentle force, you should get a discernable click and slight movement, and this should disappear when you clamp it the rest of the way.

Unfortunately, the test is easier than the remedy.

Adjusting cup and cone hubs often takes 3 hands: 1 to hold the locknut on the opposite side of the hub, and one each on the side you're working on to hold a cone wrench and a bigger wrench on the lock nut. I always put a socket in my vise and put the opposite side locknut in there (or a hex wrench of that's what that side uses, as on a newer Shimano XT hub, for example). That way, I can use my gut to hold the wheel and my two hands topside to make adjustments.

The complexity is that the "right" cone-net position may be like 1/20th of a turn from no good. Moreover, the lock nut tightening moves the cone nut and adds its own preload, so you're sort of moving 2 things at once (if you can hold the wheel and the opposite side nut still, otherwise, you're moving 3 or 4 things!)

Experience helps a ton.

It is also very handy to have dummy dropouts to test the preload and clamped force w/o having to mount it in the bike over and over again. I use a pair of blocks I made from 8mm thick aluminum stock with 10mm holes in them. The axles fit in, I do-up the QRs (without the springs) and get the same clamping I'd get in the bike. Again, at partial clamp, I check to make sure I get a little play, and then none after I clamp them the rest of the way.

The shop owes you at least a hub adjustment.

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    The two check blocks sound like a good idea. Have it patented before you see it branded and with some blue plastic stuck on. ;-)
    – Carel
    Commented Feb 6, 2022 at 15:38
  • The QR+spacers tip is valuable. Setting up cup-and-cone is tedious.
    – gschenk
    Commented Feb 6, 2022 at 16:22
  • Then I better check if I only imagined the indexing it it was some other effect I noticed in too tight a bearing? If a simple re-adjustment of the bearing pre-load would be enough it would be just a matter of a few hours to fix.
    – gschenk
    Commented Feb 6, 2022 at 16:25
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    preload on 2 wheels would be about half an hour-45 minutes for me, depending on the hubs and discs, etc. Maybe a couple hours for a first timer with other bike skills. But the shop should do it for you, IMO. Indexing feel remains mystery to me. If it were a SON dynamo we'd know why (and it would have cartridge bearings). But really tight cup and cone can feel grindy or even frozen to fingertip spin.
    – user36575
    Commented Feb 6, 2022 at 17:32
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    The new hub being notchy is the premise of the question -- the possibility that the hub is so blatantly overtightened that the balls have pressed indents into the races or vice versa.
    – MaplePanda
    Commented Feb 7, 2022 at 18:25
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As a former mechanic of nearly 30 years, yes too tight of a QR as you described can overload the bearings. This combined with too tight bearing/cone adjustment will expedite the wear. There should be a miniscule amount of axle play on QR hubs. This will compress and go away when the QR is adjusted properly.

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