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.