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Old 10-10-08, 07:42 PM   #1
aloysius
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Tensioning rear wheel

When adding tension to a non-offset rear wheel (in this case, a Mavic CXP-23), is it best to add equal tension to both sides, or is it better to add tighten the non-drive side more than the drive side? I seem to remember hearing that tensioning both sides equally will skew the dish to the drive side.
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Old 10-10-08, 08:16 PM   #2
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As long as you start with acceptable tension in all the spokes, it doesn't matter. You just want the rim to have the same dish on either side. Am I not getting something about your question?
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Old 10-10-08, 09:00 PM   #3
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It doesn't matter too much. I usually tighten evenly until I get to about 2/3 max tension, then worry about dish by tightening the drive side and loosening the non drive side. It's also acceptable to give an extra revolution or so to the drive side at an early stage.
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Old 10-11-08, 01:59 PM   #4
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Quote:
Originally Posted by aloysius View Post
When adding tension to a non-offset rear wheel .. is it best to add equal tension to both sides, or is it better to add tighten the non-drive side more than the drive side? I seem to remember hearing that tensioning both sides equally will skew the dish to the drive side.
If you have equal tension on DS and NDS (and equal spoke gauge, and spoke numbers), then the rim will end up smack bang in the middle between the hub flanges. There's no way around it, and which side you tension first doesn't matter.

If you're using a SS/track wheel, or a wheel bult for a bike with offset rear stays, then that's probably fine, but if you're using a "normal", rear wheel with external gears and the rim sitting in offset between the hub flanges - then you usually can't use the same tension DS/NDS (unless you run diff spoke gauges, or diff spoke numbers). The only way to get the rim into that position is to run a higher tension on the DS spokes.
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Old 10-11-08, 02:21 PM   #5
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Ah, I think I see what you're saying. For equal angular travel the DS nipples will tend to pull the rim to the side more than the NDS.

TECHNICALLY because of the flatter angle of the drive side spokes you should tighten those a few degrees less because of the trigonometry of the setup they will pull the wheel to that side more than the other. In practice the difference is lost among the other issues affecting the rim alignment during the building process. Again in practice you'll be bringing the spokes up to tension, truing and stress relieving in stages and all those things happening at once puts any slight difference in the pulling way down in the basement of issues.

I have noticed in the past that there is a tendency for the rim to walk to the DS side a little due to this issue but I just compensate for it during the various truings as I work the wheel up to tension. I certainly would not bother going out of your way to ensure you wind on the DS spokes by 3 degrees less of a turn each time or anything of that sort.
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Old 10-11-08, 03:14 PM   #6
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Quote:
Originally Posted by aloysius View Post
When adding tension to a non-offset rear wheel (in this case, a Mavic CXP-23), is it best to add equal tension to both sides, or is it better to add tighten the non-drive side more than the drive side? I seem to remember hearing that tensioning both sides equally will skew the dish to the drive side.
So is this a dishless wheel or a dished wheel? Telling us what the rim is only gives half the picture and your use of "non-offset" can mean a lot of things. Just to ward off a bunch of irrelevant speculation which we already have.
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Old 10-11-08, 04:12 PM   #7
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Just to ward off a bunch of irrelevant speculation which we already have.
Isn't it obvious that the OP is dealing with a front wheel drive bike here?
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Old 10-11-08, 06:44 PM   #8
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Isn't it obvious that the OP is dealing with a front wheel drive bike here?
It's a penny-farthing; sorry, but I'd have thought that this would be obvious. Really.

Seriously, I see that my original post was a bit ambiguous. I'm not building a new wheel; I'm adding tension to a factory built CXP-22/Ultegra 6600 rear wheel. I want to add a bit of tension to all of the spokes without throwing off the dish. Now, when I say the rim is not offset, I mean that the spoke holes are not drilled asymmetrically as they are on some rims (aeroheads are like this, yes?) to mitigate the disparity in spoke tension between the drive and non-drive sides. Does that help?

Last edited by aloysius; 10-11-08 at 06:49 PM.
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Old 10-11-08, 06:46 PM   #9
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p.s.
I don't have a tensiometer or a dish stick, so I'm sort of flying blind here. Maybe I should just leave it alone?
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Old 10-11-08, 07:31 PM   #10
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You've got a frame and brake pads don't you? Just tension it up to your requirements and then slightly tension the NDS a hair more to center the rim back between the brake pads.
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Old 10-11-08, 07:58 PM   #11
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Originally Posted by aloysius View Post
It's a penny-farthing; sorry, but I'd have thought that this would be obvious. Really.

Seriously, I see that my original post was a bit ambiguous. I'm not building a new wheel; I'm adding tension to a factory built CXP-22/Ultegra 6600 rear wheel. I want to add a bit of tension to all of the spokes without throwing off the dish. Now, when I say the rim is not offset, I mean that the spoke holes are not drilled asymmetrically as they are on some rims (aeroheads are like this, yes?) to mitigate the disparity in spoke tension between the drive and non-drive sides. Does that help?
Makes perfect sense. If you tighten each side the same, it will indeed start gravitating toward one side. As mentioned above, using your brake pads as a guide should help you even that out an acceptable amount. Be careful when adding tension if you don't have a meter. Too much is actually more catastrophic than too little.
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Old 10-11-08, 08:08 PM   #12
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Forgot to mention that you do have a sort of tensionometer. Tap the spokes with a plastic screwdriver handle and listen to the tone. Of course you need to know what tone to listen for. Can't help much there. There's some online freeware piano game programs and if you download one and get it going then I'd say you're looking for something around the G or A below middle C on the DS and maybe the E to F below middle C for the NDS spokes. At least tapping on the keys of Electric Piano 2.5 these sound pretty close. Get it from...

http://www.pianoeletronico.com.br/index-en.html
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Old 10-11-08, 08:45 PM   #13
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Good stuff, thanks very much.
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