Bicycle Mechanics - Wheel build - Final tension questions
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10-26-06, 08:08 PM
I just finished building a wheel (front WTB speed disc hub on a 700c mavic cxp22). My question is as follows:
Most of the spokes are at 22-25 on my park tensiometer, but maybe 8/32 spokes are lower than 20 (maybe 4 per side). Should I raise the tension on these spokes and then true (radial + lateral) again?
When I built my first set of wheels on formula track hubs, I did not have these few loose spokes. Sheldon's site for wheelbuilding is of course offline.
Thanks for your help.
10-26-06, 08:17 PM
You should probably re-true the wheel.
10-26-06, 08:24 PM
Have any idea how true the rim was before you laced it up? If you started with a "crooked" rim, that's totally understandable (and somewhat OK IMHO.) You need to build to true, not to XXX tension - within reason, of course.
If the wheel has been stressed/set and is true, I say go ride it and see what happens.
10-26-06, 08:26 PM
I don't know Park's scale but if 22-25 is your desired final tension I would back off 1/2 to 1 full turn first. Then balance tension, re-true then bring up to final tension.
10-26-06, 08:56 PM
typically, when I build a wheel I first true it up... then once it's true I start increasing the tension across the board, 1 turn on each spoke all the way arouond... recheck true, rinse/repeat till it's at the desired tension. I pre-set the spoke heads and elbows before I do truing/tensioning and as a result don't have to stress relieve more than once or twice typically.
Sounds to me as if the rim is bent, warped, or cracked. If it was me I'd loosen all of the spokes and see if the rim is bent. Then I'd decide how to go about straightening it or replace it. I keep my spoke tension within one Park deflection unit (per side on the rear).
10-27-06, 04:35 PM
I favor tension correctness over trueness, unless it's over 1.5mm out of true. I would absolutely get that tension figured out. You have a 24% tension variance there. A new rim should build to <5%. Especially one of those fancy French ones.
10-27-06, 04:58 PM
Have you plugged the numbers into the tension tnesion conversion calculator to get a better picture of what's going on?
you might be suprised at how much the tension can vary and still be a good wheel
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