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Adjusting thru axle hub with cartridge bearings?

(5 posts)
  • Started 3 years ago by ejstubbs
  • Latest reply from ejstubbs
  • This topic is not resolved

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  1. ejstubbs
    Member

    Per my protracted thread about the travails arising from my purchase of a chain wear testing tool here, the final oddity I discovered when reassembling the bike was that the locknuts on the rear thru axle hub seemed to be quite loose - not actually rattling around, but barely finger tight.

    I mistakenly assumed that the hub had cup and cone bearings, but having acquired cone wrenches of the correct sizes I discovered that it actually has cartridge bearings. I've so far failed to find any guidance on adjustment of such a hub with a thru axle. The closest so far has been the Park Tool artcile about cup and cone bearings which, confusingly, does actually have a section about adjustment of hubs with cartridge bearings at the end. However, the procedure in that section is based on a skewer-type axle.

    Reading between the lines in that article, I've adjusted my hub as follows:
    1) Tightened up the drive side lock nut using a cone wrench. (This actually appears to be more of a spacer than an actual fixing per se);
    2) On the non-drive side I snugged the 'cone' up to the cartridge bearing and backed it off a fraction, so that there was a tiny amount of lateral play in the hub;
    3) Snugged the lock nut up to the non-drive side 'cone' to keep it in place;
    4) Put the wheel on the bike and inserted the thru axle;
    5) Wound the thru axle in until the frame just made contact with the lock nuts without applying any axial pressure;
    6) Verified that there was still a small amount of lateral play in the hub;
    7) Torqued the thru axle up to the specified number of torques;
    8) Checked the hub for lateral play;
    9 ) If there was still detectable lateral play in the hub with the thru axle torqued up: loosened off the thru axle, tightened the non-drive side 'cone' a fraction and repeated steps 5 through 8 until there was no lateral play with the thru axle torqued up.
    10) Confirmed that the wheel would spin freely.

    All a bit trial and error and "doing it by feel" - though the bike certainly seems to run fine.

    However I'm unsure as to whether this is actually a valid way to go about it. I've read technical documentation for some thru axle hubs (though not mine) which suggest that you should adjust all the play out on the workbench and then just it fit the wheel to the bike, without allowing for compression like you do with a skewer.

    I'm confused.

    Posted 3 years ago #

  2. I were right about that saddle
    Member

    I thought the whole point of cartridge bearings was that you don't adjust them? This is certainly the case for motorcycles.

    Posted 3 years ago #

  3. ejstubbs
    Member

    You don't adjust the bearings but you still need to adjust the fit of the hub on the axle. That Park Tool tutorial I linked above explains it a bit, but the actual procedure it uses is specific to the skewer-type axle retention system. It also doesn't help that it keeps referring to the "cone" when there isn't one as such with cartridge bearings*. However, it does lay out the basic adjustment criteria of play between the hub and the axle when the skewer is open (for which read: the thru axle is slack) and no play when it's closed (the thru axle is torqued up).

    I think this Pink Bike page describes a bit better than I can how a hub with cartridge bearings goes together:

    Cartridge bearings replace this four component assembly [i.e. cup, cone, balls and retainer] with one complete unit that is sealed with rubber seals. A radial cartridge bearing consists of an inner and outer race, a retainer holding the balls and then two seals to keep the grease in and the elements out. There is no adjustment feature for these bearings as they are made with internal clearance or play. They are typically mounted by pressing them into a bore, such as both sides of a hub flange, and then a slip fit axle is run through with stops behind the inner race of each bearing. Nuts or top caps lock the bearings and axle into place.

    It's the 'stops' on the slip fit axle that you need to adjust in order to remove any lateral play between the axle and the hub body. As with cup and cone, the drive side one is usually fixed and the non-drive side one is adjustable, with a lock nut.

    Bear in mind that the thing that the bicycle industry has taken to calling a "thru axle" isn't really an axle at all. As with the skewer-based retention system, the actual axle around which the hub rotates is clamped in to the frame by compression. With a skewer system that compression is provided by the QR lever. A thru axle is basically just a bolt that runs down the middle the real axle that the hub rotates around - just like a skewer - but screws in to a threaded hole on the drive side 'dropout'. The clamping force is obtained by tightening the 'bolt' to a specified torque (usually 10kN).

    Actually, I think I've pretty much answered my own question with all this pontificating. Unless anyone else knows different and would be so kind as to point out the flaws in my understanding.

    * Another technical document I found describes that part of the assembly as an "adjusting collar" - but that hub design uses a plain, non-threaded axle with the 'collar' held in place using set screws, which sounds a bit rubbish to me.

    Posted 3 years ago #

  4. I were right about that saddle
    Member

    You just have time to edit the unit on that torque value if you're quick.

    Posted 3 years ago #

  5. ejstubbs
    Member

    Oops! I claim distraction by receiving an e-mail about climbing at the crucial moment.

    Posted 3 years ago #

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