Industry Nine fat wheels

Some parts of Canada call for a different approach to winter riding. These wheels are the full fat approach, marrying Industry Nine fat hubs to DT Swiss BR710 rims. The hubs are 142×15 in the front and 177×12 in the rear.

Spoke length

These rims are a good example of ERD issues discussed in my last blog. The DT Swiss rim decals include technical information stating ERD to be 549mm. I like that but it doesn’t change my process — I measured them anyway getting 547 on the front and 546 on the rear. To add intrigue the DT Swiss spoke length calculator lists 547 for this rim. Going my own way resulted in perfect penetration, a hair below the top of the nipple in each case. With single wall rims you want to be more fussy about spoke length, particularly avoiding penetration past the top of the nipple.

ERD seriously

There are two ways ERD goes wrong.

First there are variances in rim manufacturing. Some manufacturers are better than others and to some extent you get what you pay for. But I always measure and frequently find rims out of spec or find differences between pairs of identical rims. If you know what you’re working with, variances are no big deal. If you input correct dimensions, you’ll get correct spoke lengths.

The second issue is differing definitions of ERD. Typical definitions include penetration of the spoke into the nipple head, which is important for maximum strength. But how far the spoke extends beyond the nipple seat (into the rim) is unclear. It depends on nipple geometry and encodes some preference for how much penetration is ideal. In other words ERD is relative to an undisclosed nipple and opinions regarding its use.

Typically the magnitude of these errors is pretty small, maybe 0.5mm each. Additional error is introduced when you round spoke lengths to match availability (why buying spokes in 2mm increments is rough). Maybe these errors add up to a problem and maybe they cancel each other out.

This sounds like a pain but it’s not at all. You simply make your own tools and take your own measurements. The parts cost next to nothing, assembly takes 10 minutes and you’re left with tools you can use forever. Maybe it seems like a pain because you want your spokes and rims to arrive at the same time. That’s fair but getting it right the first time is always fastest.

Coaxial SON

SON hubs and lights include normal spade connectors — trim wires to length, crimp on connectors and connect to your hub. Anyone can manage this system and it works well. As an upgrade, SON offers a coaxial version that I put together today. This system requires more effort to assemble (basic soldering required) but pays you back with a number of advantages.

The upgrade comes with an adapter that connects a coaxial plug to the hub spade connectors. The new plug interface is spring-retained, which is more refined than the friction fit of spade connectors. The coaxial plug is secure but can be fitted or removed with full-fingered gloves.

Using beefy spokes

The typical spoke decision is between straight gauge and some double-butted model. For conditions outside the bell curve, there are two specialty models.

Sapim Force is a triple-butted spoke with a 2.18/1.8/2.0mm profile. They are similar to Sapim Race with a little more meat on the vulnerable elbow section. There is a cost penalty but weight and stiffness are about the same. Fatigue life is better — if you’ve been burned by broken elbows, Force might be the ticket. I often use Force on touring and bikepacking wheels to work with 32 spoke wheels when 36 might be more conventional (opening up more choices for hubs and rims).

Sapim Strong is a single-butted spoke with a 2.3/2.0mm profile. These are the biggest bicycle spokes I use and I stop at this gauge because it’s the biggest spoke that works with regular 2.0mm nipples. Strong shares the massive stiffness of Sapim Leader but has a serious amount of extra material on the elbow. People use Strong for e-bikes, cargo bikes and the heaviest touring applications. For regular day-to-day use they’re overkill though I’ve used them for riders >400 pounds.

Hope is a strategy

Hope hubs don’t have the tightest geometry or the lowest weight, but they’re solid kit for the money. Here are a couple of Hope wheelsets built this month — you might see them on the road in different parts of Alberta.

Tutorial video

Gerd Schraner, veteran wheelbuilder and author of The Art of Wheelbuilding, produced a two-hour instructional DVD called Mastering the Wheel. Now you can go to school on YouTube:

RIP Gerd.

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