Retensioning - am I close enough?
 

Wheel is dished, and laterally and radially trued. Am I close enough to equi-tension to be done, or is it worthwhile (for the non-obsessive) to tighten up tension range?

Wheel: Velocity Aerohead, rear
Mfr recommended tension, drive side: 110-130 Kgf

DS mean tension: 122 Kgf
range: -11% to +12%

NDS mean tension: 69 Kgf
range: -12% to +29%

On a new build you should be much closer than that. The variation is probably indicative of imbalances you introduced during the build, such as still having some hop when the wheel was already fairly tight, which now must be compensated for with excess differences in tension between different areas of the rim. (once tight, the rim can no longer move around the circumference to equalize).

Also look for unmatched tension between crossed pairs, it's easy to end up with one lose and one tight, and this can now be corrected, though it might require some adjustment on the opposite side.

If it's a repaired wheel it's perfectly reasonable, since uneven tension is how you compensate for and correct bends within the rim.

Ask Velocity they are great to work with, I built a set a Velocity wheels they gave good advice. I actually think you maybe fine. On my offset rear rim they said get the DS to same as you and the let the NDS fall where it is as long as wheel is true laterally and radially.

What FB said. Look for a pattern if mismatched tensions. For example, it's possible to build a straight and true wheel with too much tension on all the leading spokes on one side and all the trailing spokes on the other.
If you don't find any pattern or mismatched pairs, call it good.

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What FB said. The following resource from Park Tool may be useful in helping understand/visualize the solution:

http://www.parktool.com/blog/repair-...lator-for-tm-1

Your tensions seem good. I might tighten the drive side a touch, especially on 8/9/10 spd gearing with more acute dish. But you're clearly within a good range. Your variance seems good too.

Note also that variance in tension can be caused by many factors beyond your control. E.g. What spokes are you using? DT competitions? Double butted? I've got some older sets of spokes and just by hand feel, the stiffness and location of the butting can vary significantly.

Most tensiometers have quite a bit of error, too. And rims in their natural state can have some imperfections out of round. This means you can sum up the variances and find more than 10 - 15% variation. I expect that in the measurement. My key indicators on a build are the run-out in roundness. And second is the lateral true run out. If you have less than 25% measured variation in tension on a new rim and it's round and true to less than 1mm either way, the rest of the slack is going to be picked up by the tires (which have variation in height/width). In addition, if the profile of the rim is aero, or semi-aero, depending on the mfg., small tolerances in round require great variance in tension to pull back into true round.

One of the keys to distributing tension properly is to remove wheel after each round of tensioning and apply lateral load on the rims with both hands working around the rim, then flip wheel over and repeat (aka 'ping' the wheel). Then round/true/repeat. If you find a low spot (too tight), try to always loosen a group of 4 spokes in that group (assuming 3/4 cross lacing), ping the wheel, then repeat check for round/true. But I assume you already have done that to get to this state.

Lastly, after the 3rd or 4th iteration, I'm usually quite happy with a wheel and I install rim strip, tube, tire, and inflate. The real test is to ride the wheel under load for a mile or so. This works and seats everything into what is really close to the final state of the wheel. I then take that wheel out, remove tire/tube and then recheck tension and do a final tension/true. While a wheel never seems to be able to re-distribute tension perfectly in a shop, there's nothing like a ride with a real person to put that wheel to the test and come back with any loose spokes. Must be Murphy's Law or something! LOL! But the great part is that I find that post-first ride re-tensioning to be sort of the magical opportunity to put the wheel into a final stable true that will last a long time (or until accident ruins the wheel).

Thanks for the feedback guys. Sorry, I should have mentioned it's a used rim. I replaced a broken spoke along with a few other spokes with stripped nipples. The spokes are all double butted, stainless steel, round spokes. The old spokes are Wheelsmith 2.0/1.7 and the few new ones are DT 2.0/1.8 (I assume Competitions). I accounted for the larger diameter in the tension calcs in the OP.

Cool. I was a bit worried that the NDS tensions were a little low.

Sweet! I have the TM-1, so I'm going to download their spreadsheet, which gives a graphic representation of the tension in the wheel. I'm a sucker for this kind of thing.

Hmm, maybe I should ratchet up the tension a little. It's a Powertap with 10sp freehub.

Yeah, I've got the radial and lateral true to within about 1mm.

When pinging the wheel, I worry that I'm going to taco it, which might be keeping me back from applying enough force to effectively stress relieve it. I did hear two pings, but I'm guessing I should probably have heard more given that I only pinged the wheel after getting it up to just about final tension.

Good point. Instead of worrying about perfecting it pre-ride, I'll get it close enough and go for a spin and do a tune-up.

Fully inflate the tire and tube to riding pressure before the final truing and dish. You will probably find that the air pressure will reduce the spoke tension, and change the dish slightly. You want your best tension and truing job at riding pressure.

Give us an update I want here how it is, maybe hit a few bumps just to test.

I rebuilt a wheel with a power tap for a friend. He is about 225lbs and strong as an ox. Can generate over 800 watts for a short time on a climb. He actually broke 2 Mavic OpenPro rims.
I rebuilt the wheel the second time with a Sun rim and had to up the drive side tension to 130kg because he was breaking the NDS spokes at the nipple.
The power tap has a little extra dish because of the design of the hub which makes for lower NDS tension.

I was under the impression that the rim mfr suggested tensions are for unmounted wheels. I.e., they are factoring in the tension reduction that comes with an inflated tire.

You bring up a good observation. Often times, the spoke tension isn't what breaks a spoke, but abnormal stresses that suddenly occur at the ends of the spoke. And it's often counter intuitive that the spoke tension at rest is simply a pre-tensioning that allows the wheel to shift stress on-and-off spokes as the wheel rotates without sudden changes in tensile direction. And the non-drive side of the wheel is where the problems often are and either loosen unexpectedly or break at hub or nipple. And that's because they aren't tight enough.

This is a great tool used to visualize these tension differential.

I'm not sure about that, but I am sure they have a safety figure factored in. Check your tension, true, and dish both ways. Velocity rims are relatively stiff and may not show as much change as the lighter rims. On my rims there is about a 5 - 7% drop in tension with the tires inflated and the rim of the rear wheels moves toward the drive side about 1/2 mm. Bringing the dish back to normal reduces the tension differential slightly (that's good).
One of my friends rides Velocity Aeroheads and his spoke tension is so high it's clear off the Park chart.

I took some of the suggestions here about increasing tension, and ratcheted it up a little bit.

Per the Park spreadsheet:
DS avg: 135
std dev: 11

NDS avg: 76
std dev: 13

Here's what that looks like:
http://i175.photobucket.com/albums/w...nsionpass2.jpg

Using the visualization tool made it pretty easy to tighten up the range, to:
DS avg: 139
std dev: 7

NDS avg: 78
std dev: 7

And here's what that looks like:
http://i175.photobucket.com/albums/w...nsionpass3.jpg

I think it's time to put the rubber on the road and see how it holds up and maybe fine tune after a couple of rides. I am a little worried that the tension is pretty high (DS avg of 139Kgf), but we'll see.

Thanks to everyone for the tips, suggestions, and education in this thread and my other recent threads on related wheel topics. I feel a lot more confident about tearing down and rebuilding a wheel. :)

Prolly should've replaced the whole drive side with the 1.8s...

Seemed like a waste to replace perfectly good spokes when I only needed 3 new ones. I put those 3 on the NDS, just to make reading DS tensions easier.