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Old 05-09-11, 03:52 PM   #1
Plimogz
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Wheelbuilding: How do you go about evening up tension?

Well, trial and error learning has once again exhausted my patience, and I've come back looking for a better way that I haven't figured out yet...

What happens is this: I get the wheel pretty round and pretty true. The spokes are under enough tension that if I average the sum of all spokes' tension over how many I have, the result looks decent. But in order to get to this point, some spokes are decidedly tighter/looser than I would like them, but if I then endeavour to even out these differences in tension, true goes all out of whack. If I even out tension and then try to true, sure enough, differences in spoke tension creep their way back into the wheel...

So besides quite rightly pointing out how much I've yet to learn, does anyone have something like a convenient rule of thumb they go by when trying to even out tension?
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Old 05-09-11, 04:10 PM   #2
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I'd like some advice on this also. I just completed my first wheel build and this confused me somewhat . . . I guess I'd like to know how round rims tend to be. I'd have thought that if all parts are manufactured precisely then you ought to be able to tension all spokes similarly and expect things to be in true.
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Old 05-09-11, 04:25 PM   #3
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I use a Bicycle Research crank screwdriver for counting the turns
as you take the slack out of the spokes,
Then, those tools help you count half turns..
the spoke end pushes the tip of the driver out of the slot in the nipple,
then you get out the spoke wrench.
1/4 turn at a time, keep going around the wheel , a little bit at a time.
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Old 05-09-11, 04:27 PM   #4
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After I have trued the wheel first radially then laterally I begin to add tension. When I get close to 100kg on my tensiometer I begin to make them the same. Of course on the rear I only worry about the drive side. I shoot for a final tension of at least 110kg and sometimes up to 130 depending on the rider and number of spokes.
After the tension begins to come up I stress relieve the wheel each time I add more.
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Old 05-09-11, 04:29 PM   #5
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1/4 turn at a time, keep going around the wheel , a little bit at a time.
yes that is the best way. I used to turn the nipples down to the ends of the threads all the way around the wheel. then I do half a turn if the tension is still light I do another 1/2. then it get tricky.

that is how I used to do it when I worked in a shop. my favorite shop gives me an OK price for building wheels so I jst take my rims and hubs there.
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Old 05-09-11, 04:41 PM   #6
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Originally Posted by Plimogz View Post
What happens is this: I get the wheel pretty round and pretty true. The spokes are under enough tension that if I average the sum of all spokes' tension over how many I have, the result looks decent. But in order to get to this point, some spokes are decidedly tighter/looser than I would like them, but if I then endeavour to even out these differences in tension, true goes all out of whack. If I even out tension and then try to true, sure enough, differences in spoke tension creep their way back into the wheel...
Manufacturing tolerances and the rim joint preclude having an actual wheel which is perfectly true at uniform tension. Some rims come closer than others.

When getting as close as you can you can often move tension between a spoke and its neighbors. One or two tight spokes between two loose ones on the same side can often become one or two less tight spokes between two less loose ones.

Spreading large corrections out over multiple spokes (a half turn in the middle, quarter turn on the ends) helps avoid getting into this situation.

Where that doesn't work on rear wheels and low non-drive side tension is a concern you can compromise a bit on roundness with looser drive-side spokes next to an area of low non-drive side tension.
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Old 05-09-11, 05:07 PM   #7
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With rare exceptions - usually occuring in top quality rims - you are compromising:

Priorities Are:

1. Tension
1a. Dish
2. Trueness


=8-)
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Old 05-09-11, 05:17 PM   #8
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While trial and error may land you a decent wheel, you really need to keep tweaking the tension/trueness/roundness/dish so that it is a smaller tweak each time. At some point the tweak gets too small to matter.
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Old 05-09-11, 06:20 PM   #9
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With rare exceptions - usually occuring in top quality rims - you are compromising:

Priorities Are:

1. Tension
1a. Dish
2. Trueness


=8-)
If I'm understanding you here, you'd rather have a slightly out of true wheel with even spoke tension throughout, than one which is both straight and round, but has unevenly tensioned spokes? I had it the other way around. Time to rearrange my priorities, looks like.

On a related note, What's a reasonable amount of variation in tension which I should be shooting for? (keeping in mind that I'm new at this?) +/-20%? +/-5%?

And @zacster: I don't quite have the tweaking tension trick down. As I tried to convey in my OP, I keep trading off between even(er) tension and true. Even as I attempt to involve more spokes into my corrections, and force myself to switch more often between correcting laterally/radially or tension up/down -- I'm not quite seeing the light at the end of the tunnel.

Oh, and thanks for the advice, you fine BikeForums folks.
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Old 05-09-11, 06:39 PM   #10
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My 2 cents: even tension, and lots of it, will build the most durable wheel. Since I learn to properly tension a wheel, I haven't broken a single undamaged spoke. (Broke a couple after I jammed the chain into them, but that's another story.) My wheels tend to stay within 1mm of perfect true without maintenance for the life of the rim.

Jobst Brandt recommends adding tension until the rim starts to form an untrueable potato chip, and then backing off. Modern rims are very stiff, so I tend to go by my own calibration: when my hand starts to cramp, it's got enough tension.
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Old 05-09-11, 06:41 PM   #11
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I'll first say that I only have experience with building 7 wheels...but here are my thoughts.

I've noticed that one of my biggest mistakes is to start adjusting true too early. When I did my first wheelset, I was pulling my hair out trying to chase everything down and balance it while keeping it true. Finally I changed my approach. After first using a nipple drive to properly release the spokes at the same level of engagement all around (or you can alternately thread the nipples on until you see only a single thread showing) I start with 1/2 turn cycles. You'll go multiple times around the wheel, but instead of stopping to correct small variations, just keep winding the tension up slowly and equally around the wheel until there's a decent amount of tension on it (but not enough to quite approach completion. I think by correcting "true" too early, I was making adjustments to imbalances that were going to disappear on their own as the tension came up. If your nipple drive is releasing properly and your spokes are the proper length, simply bringing the tension up slowly and evenly seems (to me at least) to help keep things moving in the right direction. Once there is a bit of tension in the wheel, your real 'outliers' will become more obvious and you can address them at that time.

My first time fighting with this with new wheel parts had me completely de-tensioning the wheel multiple times to try again. Then I tried the above approach, and shortly thereafter my wheel was done. For my latest wheelbuild, (just this last Friday) I used the same technique and ended up with only small (easily manageable) adjustments and nice balanced tension in the end. Quite a difference. Don't give up, and listen to mrrabbit. Balanced tension is takes priority, and if you have to sacrifice something, make it the trueness.

-Jeremy
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Old 05-09-11, 07:29 PM   #12
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Good advice from others, above. I would add that I have never found a perfectly round rim. I have in some cases needed to file rim joints a bit, even on high quality rims. Normally I can get to within 1/2 mm of radial or lateral true with a good rim.
If you are really having a lot of trouble consider the possibility that the rim has been bent.
In one case I had to return a new wheel to my LBS because the rim was defective and would never be close to true.
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Old 05-09-11, 09:01 PM   #13
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Originally Posted by Plimogz View Post
If I'm understanding you here, you'd rather have a slightly out of true wheel with even spoke tension throughout, than one which is both straight and round, but has unevenly tensioned spokes? I had it the other way around. Time to rearrange my priorities, looks like.

On a related note, What's a reasonable amount of variation in tension which I should be shooting for? (keeping in mind that I'm new at this?) +/-20%? +/-5%?

And @zacster: I don't quite have the tweaking tension trick down. As I tried to convey in my OP, I keep trading off between even(er) tension and true. Even as I attempt to involve more spokes into my corrections, and force myself to switch more often between correcting laterally/radially or tension up/down -- I'm not quite seeing the light at the end of the tunnel.

Oh, and thanks for the advice, you fine BikeForums folks.

Exactly...tension+dish are my first priority...

...trueness plays second fiddle if the rim is imperfect.

Had a DT R450 turn out perfect 2 weeks ago. I had a very tight range of 24-24.5 on the Park Tool tension meter....which is very rare. That translates to 107 kgf to 113kgf. I also had the sucker all the way down to +/- .001 in. trueness. Haven't had a "perfect" rim for quite awhile until this one. Its companion was a tad off...

Typically I'll end up with a range of 23-25 on the Park Tool tension meter for my entry and mid-range rims I build up which translates to 95 kgf - 119 kgf. They often end up finishing in at .002 to .003 in. tolerance...

What makes the compromise situation even worse are rims with radial lacing. You have to make sure you don't overtension any ONE spoke nor undertension any ONE spoke. Thus it often means having to sacrifice trueness even moreso just to keep the "low" spoke and the "high" spoke in the circle so to speak.

My recommendation with radial lacing is that it's a lot better if you use quality rims....

=8-)
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Disclaimer:

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2. I like anyone will comment in other areas.
3. I do not own the preexisting concepts of DISH and ERD.
4. I will provide information as I always have to others that I believe will help them protect themselves from unscrupulous mechanics.
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Kahane, Howard. Logic and Contemporary Rhetoric: The Use of Reason in Everyday Life
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Old 05-09-11, 10:40 PM   #14
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Well, trial and error learning has once again exhausted my patience, and I've come back looking for a better way that I haven't figured out yet...

What happens is this: I get the wheel pretty round and pretty true. The spokes are under enough tension that if I average the sum of all spokes' tension over how many I have, the result looks decent. But in order to get to this point, some spokes are decidedly tighter/looser than I would like them, but if I then endeavour to even out these differences in tension, true goes all out of whack. If I even out tension and then try to true, sure enough, differences in spoke tension creep their way back into the wheel...

So besides quite rightly pointing out how much I've yet to learn, does anyone have something like a convenient rule of thumb they go by when trying to even out tension?
While you're bringing up tension: find the spot that is too high/low/out of lateral true. Before you apply the wrench, pluck the 3 spokes on either side of the hop listening to the tone. Often you will find a spoke whose tone is out of whack *and* bringing it into tension will have the desired effect of improving true. Lather, rinse, repeat, and keep going around the wheel not spending too much time in one spot.

I've recently taken to building dished rear wheels by leaving the NDS totally slack, getting the DS into even somewhat-low tension and radial round, only then tightening the NDS spokes to bring it into correct dish and lateral true. Seems to speed up the whole process with nice results.

Quantitatively? If you have an ear for tone I try to shoot for less than a minor third in tone between the slackest and tightest spokes on each side. With dial indicators I can usually get to that and 0.01" of lateral and radial runout on a new rim.

Last edited by zzyzx_xyzzy; 05-09-11 at 10:44 PM.
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Old 05-10-11, 02:14 AM   #15
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While you're bringing up tension: find the spot that is too high/low/out of lateral true. Before you apply the wrench, pluck the 3 spokes on either side of the hop listening to the tone. Often you will find a spoke whose tone is out of whack *and* bringing it into tension will have the desired effect of improving true.
That's going straight into my fledgling bag o' tricks.
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Old 05-10-11, 04:57 AM   #16
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I get the wheel pretty round and pretty true. The spokes are under enough tension that if I average the sum of all spokes' tension over how many I have, the result looks decent.
Decent is when each spoke is within 20% of the average tension. Usually that is pretty easy to accomplish. If that's where you are, there is no point in obsessing, just get on to truing.
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