Stan’s Alpha 400 rims push the envelope of weight without concessions in strength — we can go lighter but not without hurting durability. Being deliberate about spoke count and spoke model, the same rims can be tuned for each rider. The first set is built with Sapim Race spokes, 24 front and 28 rear, which makes for a sturdy build.
The second set is built with Sapim D-Light spokes on the front and rear drive side with Sapim Laser rounding out the rear. This set is 20 spokes front and 24 spokes rear, which, as the scales show, makes for a 1453 gram alloy wheelset. Less stiff but a hoot in their own way.
This is a set of XC MTB wheels using DT Swiss 240S hubs and Light-Bicycle carbon rims. The rims are asymmetric, which allows for more balanced tension between sides of each wheel. The package is put together with Sapim D-Light spokes and Sapim aluminum nipples to keep weight low — only 1464 grams for the set. Tubeless-ready using Stan’s tape and valves. Very nice wheels.
Pros measure the effective rim diameter (ERD) of every rim.
My tools are DIY, which is inexpensive. Here’s how I make them: take two black 310mm Sapim Leader spokes and cut off the elbow leaving a 300mm rod. Use bolt cutters or a hacksaw to get close, then creep up on 300mm exactly using a file or a grinder. Screw a silver nipple to each rod using a bit of Loctite so they never move. For my process I make sure the spoke penetrates the nipple until it’s flush with the bottom of the screwdriver flats — spokes stretch a little under tension so they’ll end up in a good place. That’s it. If you’re precision-minded, you can ensure nipple geometry isn’t a factor by making a new set of measuring rods any time you build with a new variety of nipple.
Usage is straightforward. Insert your measuring spokes into opposing spoke holes, counting them to make sure you’re not off by one. Pull the spokes tightly across a ruler. To make the process easier and more accurate, try raising the ruler with a shim so the spokes leave the rim closer to 90°. I suggest using a ruler with 0.5mm resolution (such as this one) but you can eyeball to the same. For most builds the spokes will overlap on the ruler, in which case you deduct the overlap length from 600mm. If the spokes don’t overlap, add the gap length to 600mm. Perform at least two measurements 90° apart and average the results to get ERD.
Note: you don’t need 300mm spokes to fashion a tool (but that length is very fashionable). Use what you have but adjust the arithmetic factor to the sum of the length of your rods. If by some trick you end up with 300mm and 299mm rods, carry on using 599mm in your calculations.
If you’re building with nipple washers, remember to increase spoke length to compensate. As an alternative, you can install nipple washers on your measuring spokes and build nipple washers right into your ERD. With asymmetric washers it’s helpful to give your measuring spokes a spin after pulling them taut just to make sure everything is seated properly. Overall this approach accounts for the end-to-end nipple/washer/rim fit and avoids errors from incorrect nominal measurements (a real thing).
Most spoke calculators will give you lengths to the tenth of a millimetre, which you’ll need to round to the nearest available length. Since measuring as above targets the bottom of the acceptable range, resist rounding down for low tension builds or on the low tension side of a wheel. In a future blog I’ll expand on the topic of rounding.
Sometimes newbies ask about cheap rims to try wheelbuilding, which isn’t the right way to think about starting. Rim quality sets the stage so inexpensive rims may serve to frustrate more than anything. If you’re apprehensive about wheelbuilding, and there isn’t any reason to be, stay away from ultralight rims and low spoke count rims. Stay away from ultralight spokes (but don’t go nuts with heavyweight spokes either). Buy a quality rim with the attributes you want to ride and you’ll do fine.
This is another build using China-direct carbon rims. These are tubulars from Light-Bicycle, a brand featured on this blog a few times. They’re nice rims. The new infosheet from LB says special skills are required to build carbon rims but I can’t agree. If you’re smart enough to use a tensiometer, you can build carbon. I like nipple washers with carbon but otherwise my process is the same.
White Industries T11 hubs mated to Stan’s Alpha 400 rims is a combination I’ve built (and ridden) in more than one incarnation. This set is put together with Sapim Laser spokes in the front and rear non-drive side, Sapim Race rounding out the rear. That puts total weight a hair over 1500 grams while remaining stiff enough for the rider. These wheels are setup tubeless with Stan’s tape and valves supporting Schwalbe Pro One tires in 700×28. A perfect combination top to bottom.