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Recently I wanted to replace my bearings and spotted something strange.

My Over Locknut Dimension has reduced by 7mm.

You can spot the difference when you compare it to the new hub:

new vs old hub

Can this happen if the bearings are set too tight?

Old cup is obviously damaged:

cup grooves

Also one very important fact, my quick release axle was broken :) :

enter image description here

So I wanted to know what is the main reason that caused the OLD reduction by 7mm? Did anyone else had similar experience?

Hub model: QUANDO KT-A12R / QR Type for Freewheel


EDITs

Dimension that I'm referring to is the "M" according to this image

Inside distance(edit) of the hub is reduced by 7mm (non-drive side bearings - drive side bearings). Depth of the cup has increased by 7mm.

OLD with the original hub is 135mm.

If I use the same spacers O.L.D for the used hub is ~128mm.

O.L.D measurement

BTW I am heavy guy - 105kg, 2m tall, that explains axle breakdown :)

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    Apart fromt he obviously broken axle, I am unsure what the problem is. Exactly what is 7mm smaller. – mattnz Oct 18 '19 at 8:10
  • Agree with mattnz. It is unclear which diameter you are referring to — the outer shell (at which position?), the inner axle hole, the bearing race, or something else. Please highlight where those 7mm on your picture are to be found. It is also likely that you compare wrong dimensions, or simply comparing two different hubs. – Grigory Rechistov Oct 18 '19 at 8:26
  • Inside diameter of the hub. O.L.D with the original hub is 135mm. If I use the same spacers O.L.D for the used hub is ~128mm. O.L.D measurement -halowheels.com/wp-content/uploads/2018/11/O_L_D_hub_3-1-sml.jpg – nexayq Oct 18 '19 at 8:27
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    With a broken axle the bearings will "dance around" inside the cup. This will slowly bend the cup inward. – Daniel R Hicks Oct 18 '19 at 11:55
  • @DanielRHicks That makes sense – nexayq Oct 18 '19 at 12:05
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So it is not a diameter, it is distance! 135 mm is a classic value for rear MTB wheels with 8-11 speed cassettes. 128 mm sounds more like a hub with freewheel would have however.

O.L.D. is a parameter for the axle (over the locknuts distance), not the hub shell width you show on the pictures. Having more washers or thicker cone washers on the old hub might explain the difference you see.

  • You're right, I changed diameter -> distance, thanks! I used the same washers. On the first picture you can see that the cup depth is not the same – nexayq Oct 18 '19 at 10:14
  • @nexayq What makes you think the cup depth should be the same? – DecSim Oct 18 '19 at 10:36
  • because its the same hub – nexayq Oct 18 '19 at 11:21
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    Ah ok. There's no requirement for it to be a set depth so I wonder if at some point they changed the design of the hub internals and changed the cup depth. If they changed the design they would also have changed the parts on the axle. Usually, a spacer or washer will be different length but sometimes the cones or locknuts themselves can be a different length. Did you get an axle with the new hub that you can compare to the old one? – DecSim Oct 18 '19 at 12:16
  • I compared axles, washers and cones, everything is the same. Somehow I managed to increase cup depth, just not sure what caused it. – nexayq Oct 19 '19 at 7:21
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The cup was not worn away by the bearings. If it had been you would have found a pile of metal filings in the hub and the axle would have been extremely loose.

Just because two hubs are sold as or marked as being the same model at different times does not mean they will be exactly the same. The design can be updated. That's what has happened here, the manufacturer moved the bearing cup outward 7 mm - which is a good idea as it reduces the length of unsupported axle between the bearing and frame dropout.

  • Perhaps the manufacture made the change after noting an unusual large number of broken rear axles? – Rider_X Oct 21 '19 at 16:30

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