Wheel build problem #2: Rim not round

Man this wheel has it in for me. Well, after fixing the cross lacing mess and getting it all trued up, tensioned and stressed…Turns out its not round either. How can I push/pull a 2-3mm bump out of a rim?

(Please experinced answers only.)

sorry about being inexperined :o , but still:
I would take it to LBS (check that all the spokes are same tention)

I checked. They are.

I would recomend LBS then, I’ve heard its hard to bash a rim into shape and that you need some kind of special tool

I was hoping for a stratigic way to tighten spokes and get rid of the bump.

Tighten or loosen spokes on both sides of the rim equally to fix roundness errors. It usually takes more adjustment than sideways errors; at least a half turn on both sides of the rim.

Did you build the wheel by doing up each spoke the same amoutn to get the tensions equal, rather than by checking the true and adjusting the spoke tension around the rim?

To quote sheldon:

For vertical truing, find the highest high spot on the rim. If the center of this high spot is between two spokes, tighten each of them 1/2 turn. If the high spot is centered over one spoke, tighten that spoke one full turn, and each of the two spokes next to it that go to the other flange, 1/2 turn. It takes a larger adjustment to affect the vertical truing than the horizontal truing. Vertical truing should usually be done by tightening spokes, gradually building up the tension in the wheel as you go along.

When building my 36" after the initial tightening I had some serious bump that needed to be sorted out, following this i was able to get it down to a minimum. Hope it helps.

hmmm well i once saw this vid on youtube where a guy was hitting the spokes with a hammer, it worked for him.

The following information comes from “The art of Wheelbuilding” by Gerd Schraner. "Radial Correction - If the rim is deformed inwards, nipples should be loosened. If the deformation is outwards, the nipple should be tightened. The neighboring nipples must also be adjusted in the same way. If the deformation is small, adjust the two neighboring nipples, i.e., the one to the left and the one to the right. "

Re: Wheel build problem #2: Rim not round

On Sun, 20 May 2007, Evan Byrne <> wrote:
>
> Man this wheel has it in for me. Well, after fixing the cross lacing
> mess and getting it all trued up, tensioned and stressed…Turns out
> its not round either. How can I push/pull a 2-3mm bump out of a rim?

Can you not just true it out?

Tighten the spokes through the bump, possibly slacken either side.
Maybe I’m not understanding the problem, but I’d regard this as part
of “all trued up”.

When I build wheels, I :
1: lace
2: tension about half way
3: get it round (radial truing)
4: finalise tension (radial truing having generally raised the
tension)
5: laterally true.
6: stress relieve
7: true
8: stress relieve
9: tweak

> (Please experinced answers only.)

I’ve never built a unicycle wheel.
I build my own bike wheels, though I do currently have one bike which
is still on its original wheels which I haven’t yet replaced.

regards, Ian SMith

|\ /| no .sig
|o o|
|/ |

In the past I have never had a rim that needed radial truing, I always just used beefy ass rims that took a lot of pull to go out of wack radialy.

I had a DX 32 a few years back… it needed redial truing from the box. Its not that common with beefy rims but it does happen. I’ve always done the same steps as what Ian said in the last post. It helps to have a good truing stand to put your wheel on so that you can see exactlly how dished the sheel is exe.

Sweet, The wheel is now perfectly round. However, the tension is messed. If I tension it now will those bumps come back?

To some extent. You need to consider tension, straightness, and roundness together, and come to the best compromise. It’s rarely possible to get them all perfect at the same time.

If you started with a decent rim, then the excursions are due to your work (sorry to say). So back off on the tension (say, 2 turns each spoke), true it nicely (both radially and laterally), stress relieve, then do 3-4 cycles of [tension 1/2 turn, true, stress-relieve]. Don’t worry about having all the spokes the same tension. When you’re done with the 4 cycles, then your spokes will be as close to the same tension as the wheel will allow.

When you have more experience building, you’ll be able to control more fully the tradeoffs between wheel strength and necessary trueness that Tom Holub was talking about.

A perfect rim (with no change in material properties at the <non-existent> joint) would basically have the same tension in all the spokes.

on this subject, I just tightened all the loose spokes on my freestyle unicycle, but now it seems to be out of true it several places. what should I do to fix this?

True it up! :stuck_out_tongue: Seriously. You can do it right in the uni frame with a couple of plastic ties for marking the rim. Take off the tire since it simplifies the process mentally. Sheldon or Schraner or Brandt will give you instructions.

I don’t belive the bumps were from my build. I tightened every spoke evenly the whole way. The rim is designed for maximum lightness so that might have been the problem.

You’ve got to accept responsability for the work that you do. If the rim was the problem, you probably wouldn’t be able to get it round. You need to accept that your work is the reason that the wheel didn’t turn out perfect the first time and that’s O.K. When you deal with mechanics , it’s very unlikely that you won’t have to tweak it here and there to get good results. Once you do this, you will learn from it and be a better wheel builder, mechanic… On the other hand, blame the parts, light, tools, you’ll always be looking for excuses.

After a lot of stressing its all perfect now. Thanks for the help.