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I was intrigued by one of the points mentioned in this question regarding grease fills, namely:

[...] which means that the ball bearings get to distribute the load over the entire surface area, whereas the axle hubs and the cones get the stress in just one continuous band of limited area.

(Credit: Sam)

The premise of this statement makes sense to me. In a wheel hub, the bearing cones/inner races are fixed to the axle, which is in turn fixed to the frame/fork. The bearing balls therefore would only contact the lower half of the cone as the bearing's internal clearance means that its upper half is unloaded, as seen in the following diagram:

enter image description here

It is obvious that the cups/outer races rotate with the hub shell and therefore have fairly evenly distributed wear, so they are irrelevant to the question.

Imagine a brand-new wheel (and therefore a hub) that is installed in a frame/fork and then not removed for some period of riding, let's say a year of hard riding. In that time, only that specific section of the cone would be worn. Would it make sense to then intentionally install the wheel in a different orientation at some point in time to allow a different section of the cone to be worn instead?

Taking the situation to an extreme, imagine a wheel that is installed and then never removed again until it is time for bearing replacement. Would the rider be able to extract a bit more life from the bearings by installing the wheel so the axle is rotated 180° from its old position to utilize the unworn side of the cone?

The question could also extend to other bicycle bearings, such as bottom brackets, where the cups/outer races only see wear at the bottom. Could one extract the bearings and then reinstall them upside down to extend their lifespan? Pedal bearings will also see uneven wear due to the rider's foot placement choice.

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    If you don’t get an adequate answer here, consider posting on the Engineering SE? There is a bearing tag there, and I have the impression that some engineers specialize in bearings. I think this is a good question, but I lack the technical background to attempt an answer, and I don’t know precisely how to search for one, either.
    – Weiwen Ng
    Dec 26, 2021 at 17:23

2 Answers 2

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Yes, this effect is real and could be used to marginally extend the life of the fixed part of a bearing.

In addition to spreading wear out from the spot loaded by the rider, in some cases it also allows a different spot on the race surface to bear the brunt of alignment issues in the bearing system, i.e. from misaligned dropouts.

I don't have data but I feel this effect is very marginal in that it won't reliably prolong the overhaul interval if you do rotate the cone to get to a "fresh" spot, and doing so isn't necessary to worry about in a properly maintained hub.

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I'd suspect "yes" as the answer, but the actual difference is likely to be small, while the labour cost is duplicated.

Imagine a bearing, with bearing balls and two races. The orientation of the balls changes all the time, so that's spreading the wear.

One of the races will rotate (the outer if its a wheel bearing, or the inner if its a BB bearing) So that race will also spread its load.

And the other race will be stationary, the cone in a wheel bearing and the cup in a BB.

I can imagine the main load bearing area wearing faster. This would allow slightly-more "slop" in the setup which is where the wear starts accelerating. If you rotated the fixed race to a less-worn orientation, the tension/preload would still need to be set correctly.

My gut feeling is that a slight worn part upside down would work just about as well as a new one. A heavily worn part should be replaced because you have it out already.

The only time I'd re-use a worn part is if replacements were't available, and I'd still try and find them.

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    Revisiting this question--for wheel hubs, it would be as simple as removing the wheel and reinstalling it in a different orientation. No bearing adjustments necessary.
    – MaplePanda
    Aug 18, 2022 at 5:44

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