mobaar

I'm preparing for my first wheel build, and I'd like some quick input on the spoke length before I pull the trigger on anything.

I'm planning on building a basic 29er front wheel with a Deore HB-M525 and Alex TD17 disc rim. 36 hole, 3 cross, 2.0 wheelsmith straight gauge spokes.

From Shimano's website:
Spoke hold diameter = 61mm
Center to Right = 35.2
Center to Left = 24.2

I'm getting slightly different ERDs though, depending on where I look.
Alex's website lists 601mm, but web consensus (message boards and retailers) seems to be 605mm. (605 seems to match better with a 622 BSD minus the 17.88mm profile Alex lists)

Using Shimano's measurements, and 605 for the ERD, I get 288.2mm for the left, and 289.4mm for the right. I'm guessing I should/can use 288mm for both since I'm only finding even length spokes available (286, 288, 290)?? I'm planning on using 12mm nipples (which I guess is the spoke calculator default?).

So 288mm spokes all around? Yay or nay?

Thanks!

wmodavis

I always measure the rim ERD in 4 or 8 positions around the rim and use the average. Then calculate and purchase spokes. Why straight guage spokes? Most everyone agrees doublebutted will build a stronger more durable wheel if properly tensioned. With ERD you used (if it's right) 288 looks like a good choice all around. But be aware the ERD affects the spoke length calculation more than the other measurements so it's most important to be correct there.

mobaar

I was looking at straight gauge to keep the budget as low as possible. This won't be my main ride, and I figure 36 spokes should be plenty strong even with straight gauge.

I may shop around more for DB spokes though.

Thanks

vredstein

Using 288 mm would be pushing it if 289.4 turns out to be a correct measurement. 1mm difference is doable, but 1.4 mm difference could be risky. If the nipple doesn't have spoke threads filling it's entire length, you have a weak spot in the nipple.
If you go with the two numbers you posted, you could get a mix of Wheelsmith 14g 288's and 289's plus nipples for $32.50 shipped. If you do Ebay, I can recommend this seller as a cheap, reliable source for Wheelsmith spokes and nipples.
https://cgi.ebay.com/ws/eBayISAPI.dll...m=230313872045

dabac

Not really. Once you have 3-4 full turns of engagement the threaded interface will pretty much have reached its full strength, any more are primarily a question of adjustability and cosmetics. As soon as you have more material locked between the flanks of the threads than you have in the core section of the male threaded part that is what'll snap rather than shearing the threads.
(moderately)Dissimilar materials doesn't change this as much as one would believe, as manufacturing tolerances prevents loads from being successfully distributed over a large number of threads anyhow.

And nipples, when they fail, usually fail by having their flanges sheared off rather than being pulled apart along the cylindrical bit.

mobaar

Just to follow up, I built this wheel up yesterday, and 288 is fine on both sides. No threads showing.

davidad

Next time use double butted spokes. !5-16 will work fine. They make for a stronger more reliable wheel.