The hard life of the hub flange

These days I rarely build 32 or 36 spoke wheels. Exceptions: dynamo hubs, disc hubs, and fixed gear hubs. I don't like building high spoke count wheels because 1) they're not as necessary now that hubs, rims, and spokes are very good; and 2) the more spokes, the longer the build time. Even as equipment has improved, one thing that hasn't changed is the advice to avoid radial lacing on hubs that are 28 hole and up. Some hub manufacturers will go so far as to void your warranty if you ignore their recommendation. I used to wonder why.

This 28 hole Tune hub, which was radially laced, demonstrates what can happen when the manufacture's advice is ignored.

That's a $200 lesson learned the hard way. (This wasn't a wheel I built, FYI.) Why did this happen? The most likely explanation: insufficient material remaining on the hub flange. Every time material is removed from the hub (e.g. drilling spoke holes), the hub is weakened.

Here's that same hub drilled for 20 hole.

More space between the spoke holes = more material left on the flange = a stronger hub. Radial lacing is permitted on this hub.

It is possible to do radial lacing on a 28 hole hub, but only if the manufacture uses a thicker flange (DT Swiss 240). A large diameter flange will also decrease the likelihood of flange failure with radial lacing. For example...

This hipster hub, with a flange diameter of 67mm, or nearly twice that of the above Tune hub, can be laced radially, even at 36 spokes, without fear of failure.

Why the talk about radial lacing? Well, it comes up because it looks cool, it builds a slightly lighter wheel (shorter spokes), so people always ask for it.

In conclusion...
I can thread and build a wheel in 16 minutes if needed, which it often was when I worked for the Animal Team. Normally I take more time to get it right – around 40 minutes per wheel – but certain wheels just take more time. This pair will take a lot of time but it’s a challenge! I’ll need some special spokes to finish them.” 

A true wheel building Jedi. Read more about that guy here.