A while back, I attempted to build a front wheel using online spoke calculators. I think I tried 3 of them, and two gave me a 284 length, and the other 283.6, so I bought 284mm spokes. They were too long. Per my usual method, I got mad at myself, and shelved the whole thing.
Recently -- a year or so later -- I'm trying to look at the situation again, and try to figure out what went wrong. In the process, I've acquired a copy of Jobst Brandt's "The Bicycle Wheel," and am finding it really interesting, if a bit over my head. In the spoke length calculation section, however, he has an example, and while the numbers make sense, and plugging in my numbers makes some sense, there is one value I don't understand.
If anyone has the book, the section I'm referring to is pages 133 and 134. He uses the term, "w" to refer to the distance from the center of a flange to the center of the hub. Actually, on page 133, he uses a capital,"W," and I'm assuming they are the same thing. Anyway, in his example, the other values make sense, but he has a value of 71mm for this center of flange to center of hub measurement. This book was written in 1981, I think, so even rear hubs were only maybe 126mm? I measured a 126 hub I have, and the flanges are 58mm apart, and the non-drive side flange is 38mm from center and drive side 20mm. What kind of hub had a flange that was 71mm from center? I'm not trying to question this well respected book, it's just that my not understanding this value has me questioning my own measurements.
Oh, for what its worth, the front wheel in question is a fairly odd, and cheap, attempt at a 590 rim, 90mm OLD wheel. It uses an old Union hub from some old cruiser, and one of the steel 590 rims sold under the name Wheel Master -- actually has no markings on it. Cheap.
Also, in Mr. Brandt's book he refers to the elongation of the spoke under tension, and that it can be around 1mm. Is it a good idea to subtract 1mm from calculated length?
I'm pretty sure the biggest part of my problem is incorrect measuring of the hub and maybe the erd of the rim. I'm just going to start all over with the measuring, but I would like to know what you knowledgeable folks have to say about the 71mm value.