Bicycle Mechanics - Spoke tension

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View Full Version : Spoke tension


phantomcow2
03-20-05, 09:16 AM
Something i noticed is that when i build my wheels, and they are all true and pretty when i go over with the tensiometer i find it common that some of the "pairs" are almost opposite. Meaning that on my Tm-1 the reading for 1 spoke might be at 18 and the one next to it, in the pair might be at 22. This is very common on every pair, so i always go out after and sort of balance the two out and i end up alright. Im wondering if what happens to my wheels is a common thing, if not, how can i prevent it? If i cant its alright, i dont mind going after and balancing the tension im just looking to save time.


legalize_it
03-20-05, 09:32 AM
actually the hi-lo tension pairing is common, and a competent wheelbuilder will correct it. tighten/loosen corresponding spokes around the pairs to bring the lo tension up and the high tension down. its not too hard and you can get the tension pretty close all the way around. some say +/-20% tension deviations are good enough, but i try to get it around +/-10%.

phantomcow2
03-20-05, 09:33 AM
well yea i usually get around 20%, sometimes less. I just want to know if theres some technique during the actual building that will do away with this, or at least reduce it. Instead of going after all is done and correcting it


legalize_it
03-20-05, 09:55 AM
the way i do it is alternate trueing laterally/radially, and tensioning. adjusting the tensions as i go. if you alternate enough and adjust the hi/lo tensions by the time its finally tensioned and true it should be pretty close and not need too much more fiddling with the tensions.

Wheel Doctor
03-20-05, 10:02 AM
actually the hi-lo tension pairing is common, and a competent wheelbuilder will correct it. tighten/loosen corresponding spokes around the pairs to bring the lo tension up and the high tension down. its not too hard and you can get the tension pretty close all the way around. some say +/-20% tension deviations are good enough, but i try to get it around +/-10%.

It also depends on the rim construction, rim quality,rim rigidity, condition of the rim, spoke pattern, dish etc. These are all variables. I get some within +-5% and others the best you can do is +-10/15%. 20% is just ugly you should be at 20% before you even use a tensionometer. Provided you have brought up the tension properly.

Retro Grouch
03-20-05, 10:12 AM
It's quite common. When I started using a tensiometer, I was surprised at how much spoke tension varience I could have in a wheel that was both straight and round.

legalize_it
03-20-05, 11:08 AM
It also depends on the rim construction, rim quality,rim rigidity, condition of the rim, spoke pattern, dish etc.

i figured that goes without saying...

Al1943
03-20-05, 11:24 AM
im just looking to save time.

To me, saving time is not part of the wheel truing process.

With high quality parts I can get within 10% on an initial build. After the wheel has been ridden several hundred miles I can usually get closer.

Al

phantomcow2
03-20-05, 11:38 AM
To me, saving time is not part of the wheel truing process.

With high quality parts I can get within 10% on an initial build. After the wheel has been ridden several hundred miles I can usually get closer.

Al
No its not part of the process, just sometimes i dont feel like going out after trying to balance the tension and sort of truing it again. I figure if i can get more efficient why not?

Well i know i usually get it in good spoke tension when im all done, except on my last wheels they had a rather large "bulge" on the seam, also causing a radial bump.

Al1943
03-20-05, 05:43 PM
on my last wheels they had a rather large "bulge" on the seam, also causing a radial bump.

This sounds like a defective rim. I usually find some kind of small irregularity in the seam area, but a large bump on a new rim needs to go back from whence it came.

I really like your cow moniker!

Al

phantomcow2
03-20-05, 05:58 PM
yea it was a defective rim. I would complain but i mean i got those rims (sub IV from Sun) on sale for 15 bucks a piece! It doesnt have any effect of riding at all, it just menas it pisses me off because its a 1mm bulge and i dont like the way it looks when i spin the wheel hard and expect to see a pretty straight thing. Thanks, I made the cow thing in image ready