onetwentyeight 

+1 to what el twe said.

11.4 i have a pair of broken hubs if you want them, or i can send pictures. snapped flanges and a crack in the body along the narrow, middle part. had a bit of a run in with a car.

11.4

128,

Thanks for the offer. If they broke from a car accident, we probably won't learn much from them (basic rule of cycling: a car can break just about any component on a bike). We're a group of rabid wheelbuilders who wanted to figure out whether there's any truth to the legends that certain hubs broke more, or radial spoking broke hubs, etc. We've focused on higher-quality hubs (not to demean Surlys, Formulas, Kogswells, etc., because they are actually very good hubs, but because we are more racing oriented and tend to see more high-end Suntours, Suzues, Dura Aces, Phils, Chris Kings, DTs, etc.). About a third of our hubs broke in crashes of one kind or another (T-bone a door and you can break a hub, but you are more likely to break a fork or frame first). The most interesting ones are those that simply broke while riding. We haven't seen any correlation with spoke tension (spoke tension ain't nothing compared to what an impact collision imposes on a hub, and the rim will/should fail long before the hub does). Nor have we seen any correlation with radial lacing, all gossip notwithstanding (there are a few exceptions with short runs of certain hubs that had spoke holes drilled too close to the edge of the flange). Hubs with higher drillings (like 36 holes) fail more often than hubs with lower drillings (like 28 holes); this is apparently because the holes actually weaken adjacent holes when they are closer together, and failures are rarely of one spoke hole but usually a zippering of 3 or 4 holes. A failure of more than 3-4 holes doesn't happen readily from a mechanical failure because at that point you've detensioned the wheel enough and you can only put so much pressure on a wheel on a localized basis. If more holes have failed, it's usually from hitting a car door, a jump off a curb, etc., and the rider is probably in bad shape as well. As for a failure lower in the flange (i.e., not at the spoke holes), it's almost always from impact damage (i.e., hitting a curb, a door, etc.); the actual break may occur later, but it usually requires a prior accident. We've seen only 3 cases of fractured flanges below the spoke holes that didn't involve crashes of some kind, but two were on inexpensive high flange hubs that weren't actually included in our study (Suzue Juniors) and one was a Phil Wood, on which we suspected someone had damaged a flange while removing and replacing the sealed bearings.

One of these days we'll get all the data together with the statistics to satisfy the engineers who might be reading. But for now, the general observation is that there's lots of smoke but not much fire regarding hub breakage. Compared to frame damage, it isn't even worth worrying about.

onetwentyeight 

interesting! why do people recommend hubs with higher hole counts? fewer broken spokes??

el twe

Doesn't that have something to do with lateral stiffness, or am I just talking out of my ass?

el twe

...forgot I could say "ass" here.

12XU

11.4 saved this thread and then some.

el twe

Srsly. Not the first time, either.

Ceya

11.4 and Sashae thanks explaining in ways I can't.

S/F,
CEYA!

11.4

You need more spokes to provide overall wheel reliability, at least in conjunction with choice of rim. You don't need 36 spokes with a high-profile carbon (or alloy) rim, but you might with a light 300 gram low-profile alloy rim.

The place where high spoke counts become a particular issue is on low flange hubs because there you may have less metal between spoke holes than you've taken out by drilling the holes. In those cases, if you tear two spokes out by breaking the metal bridge between the spoke holes, you can simply zipper around part of the rim. To my comment above, this really only gets this bad in a crash or abusive impact situation, but it does happen. This is where Chris King, who only makes low flange hubs, is quite picky about radial lacing. The real issue about radial lacing is only that if you hit a point on the rim, you are applying loads to a couple spokes that happen to show up right next to each other at the hub (where in most other lacings, adjacent spokes at the rim terminate in very different places on the hub). So if you overload two adjacent spokes on a radial-spoked wheel and the spokes lead down to adjacent, closely spaced holes on a low flange hub, they have a slightly greater chance of tearing loose. Now the incidence of this is very very rare, and it's more of a liability issue for Chris King than anything (the rider who gets injured and sues Chris King because of their own abusive riding). So I don't want to make a lot out of it. As I said above, riding-related flange failures appear to be almost nonexistent -- it takes major abuse or a crash to cause a failure. And by the way, with a large flange hub, the holes in a 36-spoke drilling are spaced farther apart so this kind of issue tends to go away.

jacobpriest

Thank you, 11.4

jjvw

This thread is answering many big questions that I didn't know to ask. Thank you!