What makes hub bearings reliable?

[weiwentg]

The recent discussion on reliable hubs (https://forums.thepaceline.net/showthread.php?t=225980) touched on a few issues, and bearing life was a big one. What makes a good bearing?

Clearly, some hubs use pretty small bearings. For example, the American Classic micro front hubs use (688 bearings on the current model (https://amclassic.com/index.php/hub-parts/688-stainless-bearing-kit-2-bearings.html)). The general sense I've picked up is that bearings can be too small, and the American Classic hub bearings are likely too small for general use. Why is too small bad?

Weather sealing is a potential factor. Ergott said in the linked thread that Phil's bearings (http://www.philwood.com/products/bearingpgs/stand.php) are well-sealed, probably more so than most competitors. This may make more of a difference to some users than others. I assume that better seals may mean more drag, but that this is a pretty minor factor for most. True?

Then, I'd assume that there's bearing construction: manufacturing tolerance, material quality, things like that. What are some specific elements here?

[parris]

I'd have to say that none of it can be looked at in a vacuum. Quality of the ball, size of the ball, quality of the race, etc, etc, etc.

[oldpotatoe]

Good design, quality bearings(grade 25), regular service and proper adjustment.

[bikinchris]

Back in the day:
Department store bikes had just as many bearings that were the same size as the top quality bicycle hubs. They were junk. The bearing surfaces were practically pot metal and the bearings themselves were 200 grade or worse.

Low quality bike store quality hubs also had the same size and quantity bearings as the best hubs. The metal of the bearing surfaces was a high quality metal 4130 Chrome Moly and the hub ball bearings were usually 100 grade.

Medium quality hubs had 4130 cones that were heat treated to make them harder. The bearings were 25 grade.

Top quality hubs had hardened cones and cups that were polished to eliminate the break in period.

Cassette bearings in hubs today have bearings that are difficult to know the quality of. I know that the bearings I get from Phil Wood, Enduro and a few others are top quality.

[11.4]

Bike wheels rotate slowly, handle very little load and very little heat, all compared to what many bearings have to deal with (just think about a wheel bearing on a pickup truck). And we tend to get better quality components than that pickup truck does. It comes down mostly to how they are maintained and how well the enclosure (hub seals, race design, etc.) are working. It's not at the top of my list for maintaining a bike, at least with even borderline decent hubs.

[weiwentg]

Good design, quality bearings(grade 25), regular service and proper adjustment.

You know, that raises a question: are some hubs easier to service than others? And do some hubs need more frequent service than others (e.g. maybe Chris King?)

[dustyrider]

I would add a larger emphasis to end-user serviceable features/design of the hub then actual bearing quality. I mean there are folks out there running ceramic bearings as we type...:rolleyes:

A good hub should allow the user to keep bearings in a reliable state for a reasonable amount of time given the riding conditions. When they need replacing, remember those little balls of steel, or ceramic, are the disposable part. They should be easy to acquire and easy to service.

Sealed cartridge bearings are pretty reliable when they just have to spin, and loose ball/cup cone steel bearings can still be picked up at the local hardware store, both of which would be my preferred hub bearing choice.

I believe there are quite a few of us here that have hub bearings with a couple of decades worth of miles and they’ve never been replaced. Is that hub design, service-ability, bearing reliability, ...?

[zmudshark]

Manufacturing tolerances.

[ergott]

Smaller bearings are less ideal because of the lower load capacities.

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[buddybikes]

Used to love taking apart my record and dura ace hubs (70's and 80's) and just stare at the cones, versus the ones I fixed. Knew nothing about bearing qualities. We, I am sure, changed worse quality bearings than the used ones in the hub just for general maintenance.

[Ronsonic]

Precision of manufacture and sealing. Which has been pointed out.

Our bearings don't work hard, but they have to survive the elements so they're dependent on either the quality of seals or the quality of maintenance. I don't think I've ever seen a hub or BB bearing done in by anything but neglect either corrosion or maladjustment.

Headset bearings have a weird life. They are a thing designed to turn, and turn smoothly they must. But they spend most of their life doing almost nothing but getting rattled in place. The key to their life is, again, cleanliness and correct adjustment. Whatever makes them easy to seat accurately and adjust precisely makes them last.

[oldpotatoe]

You know, that raises a question: are some hubs easier to service than others? And do some hubs need more frequent service than others (e.g. maybe Chris King?)

Certainly some are easier than others. Some with cartridge bearings are a breeze and some are a PITA(CK, as mentioned). Some with bearing balls, loose are easy(like Campag) and some with balls are way more difficult(shimano 7800)...
BUT bike hubs don't need to be that complicated. Not high speed, not high temp or pressures..why ceramic means 'open wallet and empty' for no performance gains at all. Ceramic balls would only make sense if you rode with that amount of $ in pennies in your jersey pockets, then took them out when you got ceramic..

[thwart]

Ceramic balls would only make sense if you rode with that amount of $ in pennies in your jersey pockets, then took them out when you got ceramic..

Thanks for the morning chuckle... :D

[zap]

Smaller bearings are less ideal because of the lower load capacities.

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Agreed. As a one time American Classic tiny front hub owner.........oh wait, I still have that front wheel hanging from a hook with new bearings.

[Lewis Moon]

I'm rebuilding a Bontrager Racelite rear hub and I was always told that it was basically a DT240 (it has the star ratchet). I ordered bearings for a DT240 only to find that, on this hub, the freehub side bearing was different than the NDS side. I did a search to see if there was a different model and I couldn't find any reference to the DT240 ever having two different sized bearings. So...I pulled out my trusty hand lens and started looking for markings on the old bearing. I found "Swiss Made" and 3802. When ordering I came to find out these bearings have two sets of bearings in deep grooves to combat side loads. Not a bad idea for the bearing that takes the load from the free hub.
https://medias.schaeffler.com/medias/images/skizzen/0008F527_med_in_0k_0k.gif

[bicycletricycle]

the seals on the bearing can be augmented by the hub itself. Some hubs have the bearing facing free air exposing the seals to muck directly, others put that bearing behind some kind of mechanical component which can potentially help keep the muck from even getting to the bearing.

[93KgBike]

I miss loose ball BBs. My old record bb was very calming and satisfying to service. So much so, that I did it at least 3-4 times a year; way way way more than necessary. Loose ball hubs were less fun, although they did at least impart cone wrench finesse, which is kind of a lost art. I guess the same could be said of headset wrenches, which only old heads and anachronists need now.

[Charles M]

Good design, quality bearings(grade 25), regular service and proper adjustment.

And proper spec BB shell in the frame. If anything is slightly tweaked, the bearings especially Press fits will quickly wear out trying to seat themselves.