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In theory, could a bicycle hub last forever if you kept overhauling it (and getting new spokes and rims and etc.)?

I'd like to know about all the hubs, but what really interests me is whether or not cassette hubs and front hubs can be overhauled over and over and last 'forever'.

  • I would summarize not if made of aluminum (which virtually all are), which has no fatigue limit, meaning eventually the hub itself will disintegrate. If made from Titanium – mattnz Apr 10 '17 at 20:14
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    Sooner or later the bearing races (cups) will wear out. And each time you replace the rim and spokes you put extra stress on the flanges. Especially if radial spokes are used the flanges will eventually fail. Also, there's not really much point in overhauling (other than doing the bearings at reasonable intervals) as it's cheaper to buy a whole new wheel than to replace the rim and spokes on an existing hub. – Daniel R Hicks Apr 10 '17 at 20:43
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    How long is forever? See the 10000 year clock project. longnow.org/clock – mattnz Apr 10 '17 at 22:21
  • A well-selected hub with reasonably light usage, regular maintenance and a supply of spare parts can last for a (well over) lifetime. You might even go full "ship of Theseus" mode and replace "just" the shell at some time. I'd prefer replacing the whole thing every x years (simpler, maybe cheaper, hubs are not that expensive anyway), but its your bike. – Matej Lieskovsky Apr 11 '17 at 9:57
  • Yep it could :D If you could replace bearings, pawl springs and pawls. – Greg Aug 4 at 5:35
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If the shell is aluminum and we're talking about the whole thing and not just the bearing races, the literal answer is flat out no, because aluminum doesn't have a fatigue limit. It will crack eventually.

As to the question of can a hub bearing race, real or hypothetical, last literally forever in any kind of use, that's the kind of question everyone likes speculating about but I think you need a bearing engineer to begin answering, so I'll say I don't know.

In practical terms the answer is most cups/cones with enough preventative overhauling can be made to last a very, very long time, much longer than they normally do. In my experience for a nicer hub with very hard, precisely made races it's more or less indefinitely. I've tried to keep more modest hubs going the same way and wound up wearing them out despite my best efforts, but I'm heavy and ride where it's wet.

There's a side conversation about using ball bearings whose hardness is a good match for the races, which is a topic usually glossed over in bike shops. I don't know the details but I've come to suspect it can matter quite a bit in the long-term lifespan of a hub.

How much flex the axle is experiencing is also a pretty major factor over time.

All freewheeling mechanisms wear out eventually as far as I know.

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Bearing engineer piping in - technically you could have a 'forever' bearing using the right materials and lubrication - OR, change in envelope which increases the bearing capacity to the point where the applied radial, axial, and moment loads are so miniscule compared to capacity that they never wear. This method of survival is dependent on your seal being impervious and grease life to prevent FOD and marginal lubrication conditions.

Keeping the mean hertzian stress level low, or replacing the parts with wear resistant material grades are the two options to go from normal to extreme longevity. Bear in mind, the most innovative bicycle bearing is still a normal commercial item when compared to what is engineered for, say, a turbine in a rocket, so there's levels of development that haven't made it to the consumer market as the price would be prohibitive.

I would wager that for approximately $22000USD, I could make you a set of hub bearings that would last longer than the life of yourself or the bike. Bargain right? :)

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A front hub contains a few parts that wear out but can be replaced: balls, bearing cone, axle, and hub (more modern designs exist). I would not call that lasting "forever". Put in a different way: if you don't replace these parts over time, the hub will break.

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    Most modern cup and cone hubs don't have replaceable cups. Once those start pitting, the hub shell is lost. – ojs Apr 10 '17 at 19:30
  • But some modern design have closed ball bearings which can be replaced and where the hub doesn't wear out. – Christian Lindig Apr 10 '17 at 19:38
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    Yes. These are called cassette bearings. Look up metal fatigue before claiming that these last forever. – ojs Apr 10 '17 at 19:58
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Not all hubs are fully serviceable. I have a Chris King I had to have totally rebuilt for over $200. Even had to replace the body. You can get Chris King stainless steel hub for like $500 US that would be hard to destroy in a lifetime. The Chis King hubs over $1000 are more for strength (and they will last a few years).

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Yes, in general they can, if they are overhauled when needed ( loose ball or cartridge bearings). And most importantly, the the hub bearings needs to be adjusted correctly, not too tight or too loose...

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