mrmb

Been having a hard time with this one. Lateral trueness, dish, even tension....doing well. Got it down.

Some of my builds come out with perfect radial trueness and I don't know why. Others have a mm or two of "wheel hop" and no matter what, I can't get the "hop" to go away.

As I tighten the spokes (usually a group of 6) to pull IN the rim at the offending area of the rim with a HOP, then loosen the opposing spokes at the opposite side of the rim where there is a DIP....nothing changes in regard to radial trueness.

What am I overlooking?

mrmb

When I say "vertical trueness" I mean "radial trueness".

cxwrench

There are 2 very important things to look at when you're looking at radial runout...at least when building new wheels.
1. The new rim must actually be very round. Many are not and this causes problems.
2. Your starting point when putting nipples on spokes must be as close to exactly the same for every spoke/nipple as possible.
I have one of those Problem Solvers things that goes into an electric drill. The end looks like a flat screwdriver w/ a hole in the center that fits a piece of 2.0mm spoke. You can adjust how far it sticks out. The little piece of spoke stops against the spoke as it comes through the nipple. This will assure that every nipple is screwed on the same number of turns and gives you a very even starting point. I then add tension the same on all spokes and usually the rim stays very straight and round as I bring the tension up.
If you're working on a wheel that's been built and ridden this all changes.

Le Mechanic

Don't worry about the opposite side of the rim, just focus on the high and low spots where the radial runout is located. Having a round rim and getting the spokes started evenly will definitely help speed up the process, but it's simply a matter of tightening or loosening the spokes in a given area to raise or lower the rim in that area. The tricky part is keeping the spoke tension relatively equal while keeping the lateral runout in check. I find it easiest to do all of these simultaneously. I made a video a year or so ago on how I like to tension and true a just built wheel. Maybe some of it may be helpful.

zandoval 

OK Stud... Ya got me. Not that I rebuild wheels very often but it sure looks like I need one of these. How about a pic or a link?

Thruhiker 

Heres the one I use. You can get different lengths. As your screwing the nipple on the spoke will push the bit out. Not as cool as the problem solvers that's adjustable though. Might have to upgrade. Lolhttps://www.amazon.com/dp/B07GFQ7CD9/ref=cm_sw_r_cp_apa_glt_fabc_49ND5SQZ87WZG6NVMMEA

70sSanO

You can always back the nipples out so you have the same amount of thread showing on each spoke. Then just turn them in the same amount on each spoke to tighten. The idea is to have all the spokes threaded equally. Start at the valve hole and go all the way around.

John

tcarl

I work on getting the vertical trueness pretty early in the truing process when spoke tension is still pretty low. That seems to work better than later on when the tension is higher. You mention tightening the spokes in groups of six. Sometimes I'll do that many if it's a really big (long) hop, but usually will only tighten 4, or sometimes just 2 spokes.

Dave Mayer

Put the wheel on the truing stand. Find the specific point on the wheel that is too far out from the hub. Tighten the closest single spoke by 360 degrees. In order to prevent that section of the rim from going laterally untrue, tighten the spoke on the either side of that spoke you just tightened, by 180 degrees each. 180 x 2 = 360, so the lateral trueness of that spot on the rim is more or less maintained.

Repeat as necessary. Obviously, for a spot on the rim that is too close to the hub, then you need to loosen the closest spoke by 360 degrees, and then loosen 180 & 180 on either side.

JohnDThompson 

I use the Bicycle Research version:

cxwrench

zandoval Here ya go:
Problem Solvers Holy Driver

cyccommute 

+1. There may not be a spot on the opposite side of the wheel that corresponds to the problem area. Turning the wheel 180° and trying to to “fix” the problem is just introducing more problems.

oldbobcat

Hops usually occur because we ignore the radial trueness in our effort to attain lateral trueness. Generally, I can flatten a hop by tightening the spokes on both sides in the high section. If it's a wheel I'm building myself, I'm usually truing out the hop before the wheel gets too tight. If it's an old wheel, I'll carefully loosen the whole wheel by a half-turn and start over, paying more attention to the hop.

davidad

When I build a wheel I start by setting the nipples at the same depth, then getting the radial runout true. As the tension begins to rise I make minor adjustments to the lateral runout still concentrating on the radial. Rising tension makes it more difficult to correct radial runout errors.

deacon mark

In all the good responses in can still just be an issue with the rim itself. I have found that if the rim is well made and round, as long as you work all three together and start with nipples all in the threads the nearly the same, then radial seems to come out ok. I have also had rims that no matter what I did I could not get rid of the hop. I recently rebuild a Kinlin 279cx that had a pretty good hop. I could never get rid of the hop without cause problems with tension and lateral trueness. I bought a replacement and used the same spokes and nipples and the wheel came out wonderful and round without any stress in the build. Some rims are just not round out of the box.