Building as always
October 13, 2019
Wheelbuilds continue to trickle through the shop. Here’s a few snaps of recent builds:
Wheelbuilds continue to trickle through the shop. Here’s a few snaps of recent builds:
This wheelset uses Paul Component track hubs laced to Stan’s Alpha 400 tubeless rims with Sapim Laser spokes and alloy nipples. Total weight is 1545g. Additionally this wheelset is getting tamper-proof torx bolts for a little extra lockup security. The bolts are a Paul upgrade option.
I own a few spoke rulers. You’d think they’re all the same and mostly they are.
My daily driver is the Sapim ruler at the far left — it does its job very well. It also tries to be a spoke diameter gauge but isn’t as successful. The purple Pi ruler, next in line, is pretty novel with its center channel for aligning the spoke. This helps measuring used spokes, which are never straight. I like that it’s marked in half millimetre increments although the bright finish detracts from legibility. The Phil Wood ruler is heavy in a good way and pleasing to use. It has the best spoke diameter gauge although 2.2mm is conspicuously missing. The Cyclus and Park Tool rulers are similar, however Cyclus gets extra marks for putting its graduations on the spoke path. The VAR ruler is similar but adds nipple measurement, which is clever and useful. The DT Swiss ruler doesn’t feel like a real tool. The Unior ruler is on the same level as Park, which means good enough. The Filzer tool on the end is conspicuously similar to the Unior tool — since Filzer is a marketing company we can probably guess who made their tool.
In the last little while I’ve done a couple wheelsets using DT Swiss hubs and rims. Both sets use DT 350 hubs; one rider selected R470db rims while the other chose RR521db rims. If you’re thinking about building a set of wheels yourself, I can testify these rims make the work painless.
Pictured below are two wheelsets built with 650b Pacenti Brevet rims, one built in March and another more recently. I was happy with the steadiness of the rims and would recommend them if they meet your needs. The first set uses Campagnolo hubs; SON and Shimano hubs on the second.
Rear hex drive nipples were designed to handle increased torque but they also prevent builder’s marks on external nipple surfaces. Some people like rear drive because the turning direction is intuitive — clockwise is tighter. Since the external interface exists just the same, you can forget the rear hex drive if you prefer (or treat it as a backup to save the day if a nipple cracks or rounds off).
The Sapim hex drive is 5.5mm. It’s a balance between making the interface as large as possible while leaving room for tool clearance at the rim holes. Even so a thinwall tool is often necessary. I have three in my toolbox. My main tool is the Park SW-15, a 3-way that fits nicely in the hand and provides good leverage. Blue tape marks the 5.5mm end. The Park Tool SW-18 is a screwdriver design, which reaches into deeper rims and may fit better in race toolboxes. The Sapim factory tool is excellent quality and handles even deeper rims but too deep for everyday use.
This is a sweet set of 650b gravel wheels. They’re put together using Onyx rear and SON front hubs paired with Light-Bicycle carbon rims. These wheels are destined for a year-long journey so I’ve selected Sapim Force spokes, which makes builds more bulletproof. For more casual use lighter spokes would definitely work.
The talented Karl Stoerz published a pictorial discussion of thread penetration, a helpful supplement to my last post. I agree with Karl but point out his pictures apply to most but not all nipples — it’s always useful to check yours to avoid surprises. Some nipples bottom out before the spoke can penetrate past the end at all.
The correct spoke length is one that penetrates the nipple just right — not below the screwdriver flats and not past the top of the nipple. You don’t want to go too short because spoke threads reinforce nipples internally. Nipples, particularly aluminum nipples, have higher failure rates when paired with short spokes. You don’t want to go too long either. I define too long as past the end of the nipple. This is strictly true for some nipples however many can tolerate a couple turns past the end without issue. Turning past this baked-in limit causes nipple threads to grind into the unthreaded spoke shank, which creates a weakness in the spoke and is associated with spoke breakage.
Spoke length calculators output lengths to the tenth of a millimetre, which must be rounded to match available supply. There’s no universal rounding algorithm because it depends on how you calculate spoke lengths in the first place. It depends on ERD measurement technique.
In my process I use measuring tools based on theoretical spoke penetration to the bottom of the nipple screwdriver slot. I don’t want my actual spoke penetration to be short of this mark, so I’m cautious about rounding down. My baseline is rounding to the nearest millimetre. If my target tension for a spoke is high, say 125kgf / 1200N, I’m not bothered rounding down as much as 0.6mm. This is because spokes stretch a fraction under tension and stretch is more pronounced at high tension. This logic particularly applies to thinner spokes because thinner spokes are more elastic. The opposite holds as well — a spoke built to 60kgf could be rounded up 0.6mm. As an example when building a rim brake rear wheel, where tension is quite imbalanced between sides, a wheelbuilder might round up on the low tension side and down on the high tension side if both lengths are halfway between sizes.
(Hopefully you can see this rounding logic doesn’t make sense if your theoretical spoke length targets the end of the nipple. In that case you would rarely round up.)
Traditionally spokes are stocked in two millimetre increments, which invites compromises depending on your calculated lengths. You can be forced to reckon with the the risks of going too short or too long. Maybe the uncertainty steers you to brass nipples instead of aluminum. Maybe it causes you to pick up nipple washers as an insurance policy. Bottom line: it’s not doing you any favours and to build the best wheels you ought to shop in one millimetre increments.
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.
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.