I trued a couple of wheels and didn't realize until afterwards that my truing stand was a bit out of center. There's ~0.5mm gap between the locknut and dishing gauge feeler on one side of each wheel meaning that the wheel is off-center by ~0.25mm.
Is this enough to be concerned about? Is this going to negatively affect braking or brake pad wear?
Is there an acceptable range for dish or does it need to be spot on?
And to dish the wheel to center, do you think it'd be better to loosen one side of spokes or tighten one side before truing it again?
The nature of any mechanical adjustment is that you will NEVER get it spot on. Thats physics for you. I would have thought that its just a matter of tightening on one side and losening on the other. Then again I dont true wheels. I give em to the mechanic to do.
Originally posted by dorian I trued a couple of wheels and didn't realize until afterwards that my truing stand was a bit out of center. There's ~0.5mm gap between the locknut and dishing gauge feeler on one side of each wheel meaning that the wheel is off-center by ~0.25mm.
Is this enough to be concerned about? Is this going to negatively affect braking or brake pad wear?
Is there an acceptable range for dish or does it need to be spot on?
And to dish the wheel to center, do you think it'd be better to loosen one side of spokes or tighten one side before truing it again?
Thanks for any input.
Dorian
It is acceptable, but if you can bring it closer to perfect with another pass, make the adjustments. Make sure you remove any spoke wind up and stress relieve again.
Interesting discussion. I have no knowledge of wheel specs, but agree that 0.25 mm dish offset (.010 inches) is probably within the frame centerline tolerance in the first place, and not critical. The location of the brake mount bolt also has a tolerance...again, seems to me that within .010 from centerline of the frame for the brake bolt would be acceptable within a tight spec.
Also, seems to me an offset dish would only require a minute shift in lean angle of the frame to correct as you ride. If your CG is about 1 meter off the ground, then leaning .014 degress from vertical would correct the shift (arctangent of 0.25mm/1 meter)..certainly nothing you'd notice while riding.
Haven't built any wheels, but I'd think getting the optimum design tension in every spoke is a lot more important than measuring dish or runout tolerances to this level.
ask DHK mentions, maintaining a good balance in tension is very important.
althought 0.5mm isn't that much, if you do want to adjust the dish, a combination of loosening one side and tightening the other side is the way to go.
as to the art of adjusting the dish if u decide on that course of action......it all depends on the tension already on the spokes of the respective sides of the wheel. I would go for a loosen/tighten techinque, unless the spokes are already noticably tight or loose in which case i would do the opposite...if that makes sense.
Depending on the spoke tension on the wheels, sounds like a quarter turn to bring it in so it is perfect. Make sure you have stress relieved the wheels and retrue.
Thanks for all the replys. I got the dish pretty much as good as it's gonna get, but the tension now seems a bit high. I wasn't really paying attention to this before. So now I'm going to lower the tension in the whole wheel and start over once I get a tensiometer, which should be here Friday.
Originally posted by dorian Thanks for all the replys. I got the dish pretty much as good as it's gonna get, but the tension now seems a bit high. I wasn't really paying attention to this before. So now I'm going to lower the tension in the whole wheel and start over once I get a tensiometer, which should be here Friday.
Stress relieve and check spoke alignment. After you have done that, you may find that spoke tension is lower. Even spoke tension is a key to a reliable wheel.
