Join Date: Apr 2009
Location: New Rochelle, NY
Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
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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.
An ounce of diagnosis is worth a pound of cure.
“Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin
“One accurate measurement is worth a thousand expert opinions”
- Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance
Last edited by FBinNY; 04-24-11 at 03:23 PM.