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Old 06-02-10, 09:56 PM   #1
vantassell
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Wheel Building/Truing Process

Ok, so I got a new set of wheels that were badly out of true. I took this as an opportunity to really learn about wheel building. I laterally trued, radially trued, rechecked lateral true, then checked dish...and repeated (about 50 times). I didn't have a tension meter so i just kind of guess as to what I thought the spokes tension should be. I've realized that this isn't a good method for a newbie so I got me a park TM.

My question, how far in the truing process do I go while trying to keep spoke tension even? I've heard that in a perfect world with perfect rims/spokes/hubs I'd be able to build a true wheel that has perfect tension. But since the rim/spoke/hubs aren't perfect, in order to get a true wheel my spoke tension will vary a little.

Do you check spoke tension while truing? after truing? or only before truing and then let the rim decide how the spokes should be tightened?

How much deviation between the spokes do you guys allow for? (i.e. one spoke measures 23 on the Park TM, is it ok if the next one is 25?)

Also, is there any place that shows how much difference there is in tension between drive and NDS? How to disc brakes affect DS and NDS tension differences?
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Old 06-03-10, 04:36 AM   #2
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Ok, so I got a new set of wheels that were badly out of true. ..I didn't have a tension meter so i just kind of guess as to what I thought the spokes tension should be. I've realized that this isn't a good method for a newbie so I got me a park TM.
Wise decision. not only will it help you do better work, it'll also make it possible for you to engage in constructive conversation about the quality of your work.

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My question, how far in the truing process do I go while trying to keep spoke tension even?
It'd depend on if you're building from scratch, if you're servicing an already built wheel and it'd vary with the person. There probably aren't two people anywhere who'd do it in exactly the same sequence.

When starting from scratch, or from a wheel where I have reason to believe the tension balance to be OK, then I do the trueing first, then I check and adjust tension. If this reveals tension imbalance then tension balancing while maintaining true becomes a dual process.

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I've heard that in a perfect world with perfect rims/spokes/hubs I'd be able to build a true wheel that has perfect tension. ...
The impact of hubs on trueness is negligible, unless you do something challenging like using mismatched hole counts. The impact of spokes on trueness is so-so. Thin spokes can be prone to windup, but this usually represent itself as wheels not staying true during use. If the set of spokes you're using is uniform and of the correct length they really shouldn't affect true to any extent. Achieving true with spokes that are prone to wind up can be harder, but once there it shouldn't be an issue.
The rim is the big culprit. It can be off from delivery, it might have gotten dinged during riding.

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...But since the rim/spoke/hubs aren't perfect, in order to get a true wheel my spoke tension will vary a little.
Indeed. Usually you get better durability by prioritizing tension over trueness. But if (rim brake) clearence gets too bad at even tension, then you haven't got much choisce if you want to keep the bike rideable.

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...Do you check spoke tension while truing? after truing? or only before truing and then let the rim decide how the spokes should be tightened?
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How much deviation between the spokes do you guys allow for?
10% is probably a fairly common goal to shoot for. But it'd depend on price range, intended use, rider expectation and builder workmanship/pride.

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...i.e. one spoke measures 23 on the Park TM, is it ok if the next one is 25?...
haven't got the chart at hand, but as I recall the Park TM translation chart isn't linear. 23-25 might not be OK when translated to kilos.

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...Also, is there any place that shows how much difference there is in tension between drive and NDS?
Damon Rinard's spocalc will calculate tension difference (in %) if you input the wheel data into it. Might be more spoke calculators that have this ability.

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How to disc brakes affect DS and NDS tension differences?
Any design feature that leads to different spoke angles for the different sides will create tension differences. But a disc brake front will be less off than an average rear wheel. Disc brake rears usually have the NDS flange closer to center of the axle than older rim brake hubs, so they can have less of a tension imbalance thanks to that.
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Old 06-03-10, 02:44 PM   #3
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Based on the Park conversion chart 25 deflection units is 121 kgf for a 2 mm spoke, 173 kgf for a 1.7 mm spoke, and clear out of the ball park for a 1.5 mm spoke. That's more than what is recommended for any rim that I'm familiar with, and I run some pretty high tensions.

The tension differential between the drive side and the non drive side is whatever it takes to get the rim centered. From my experience with typical 9 and 10-speed road wheels the non drive side spokes have had about 63% as much tension as the drive side. The trick is to get enough tension in the non drive side spokes so that they don't break at the "J" bend from excess flexure and at the same time not exceed the recommended tension for the rim (by too much) with the drive side tension and also have a centered rim. I usually exceed the rim's recommended tension but not by too much, so far no rim failures.

Last edited by Al1943; 06-03-10 at 02:55 PM.
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Old 06-04-10, 04:31 PM   #4
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Wow, I hit the mother load. Thanks for answering all my questions, wow.

I think i'll just add into my process checking tension after I check dish, and start over truing the wheel if I have to adjust the tension too much. It's good to know that the tension might have some priority over trueness, but I think just going back and forth fixing tension and then trueness and then tension and then trueness i'll eventually get to a good balance.

I'll check out that spoke calculator to see the calculated difference, but 63% is a good estimate to know if i'm in the right range or not.

For the example of 23 vs 25 on the meter, I was just using those numbers as an example. I'll try going with a 10% spread.

Thanks a lot for the help guys.
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Old 06-04-10, 04:39 PM   #5
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120kgf is fine for rims with eyelets and deeper section rims. Really, it depends on the rim.

when you inflate a tire to what you expect to ride it at, then you'll see that 120kgf quickly drop down by 10~30kgf.
you obviously want to fix the tension in spokes that have fallen below 110kgf.
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Old 06-04-10, 09:05 PM   #6
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120kgf is fine for rims with eyelets and deeper section rims. Really, it depends on the rim.

when you inflate a tire to what you expect to ride it at, then you'll see that 120kgf quickly drop down by 10~30kgf.
you obviously want to fix the tension in spokes that have fallen below 110kgf.
Well, that seems to be very random. Another mechanic and I at work did some testing on that. On tubulars, the tension always dropped. On clinchers, sometimes it did, sometimes it didn't. Sometimes the drop was a lot and other times just a bit. I've never seen a 30Kgf drop from a clincher.

As for truing, that is the last part of the wheel build for me. I always build the same way. When I first lace the wheel, I put each nipple on the spoke with three complete turns. Once all the spokes are in the wheel, I put the wheel in the stand and turn each nipple one complete turn. I will do one complete turn of the nipple until the tension starts to get up there. Then I back off to and only do a 1/2 turn on each nipple. As I get closer, it becomes 1/4 of a turn.

When the wheel is close to the final tension is when I start truing. I'll get the wheel true and round. Once this is done, I will get out the tensiometer and check for tension. This is when I go for a balance of tension per spoke, trueness and roundness. When I am happy, I stress relieve and check for true, round and tension again, make any corrections if needed.
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Old 06-04-10, 11:02 PM   #7
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oh, right, I only see 30kgf drops, because I, sometimes, do the squeezing/twisting stress relieving and tire mounting in the same step.
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