Bicycle Mechanics - spoke length blues

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long john
04-24-11, 03:12 PM
hi all, i am building a wheel and i have used 3 diffrent web wheel spoke length sites.
i cant get it right ever. I have a shimino HC-110 36 hole rear hub with super champion gentleman 81 rims. help please i cant bear to take apart any more spokes. :bang::bang:

FBinNY
04-24-11, 03:20 PM
the key is to stay with the same calculator, because once you get used to it you'll know if it gives you high or low numbers and by how much. It'll be consistent, so once you know the fudge (correction) factor it'll be bulletproof.

The problem really originates in the ERD measurement. Some rim companies specify this at the nipple seat (as I do) while others add 4-6mm to the diameter to allow for the height of the nipple. Also, the basic formula calculates to bring the spoke back to the same diameter as the ERD entered, but a few add 2mm to adjust for the thickness of the nipple head.

So the issue is correcting for the nipple seat/nipple head difference. I avoid the issue, by measuring all the rims myself, at the nipple seat, using the basic formula which I have in an old HP calculator, then adding 2-3mm to reach the top of the nipple. Eliminating the unknown variables gives me results I can count on every time.