Wheel building - getting rid of hop
 

As my intro to wheel building, I swapped out a damaged front rim on my easton EA90SL front wheel (24 straight pull spokes). I re used the same spokes, which is probably not the best idea according to a lot of posts I read after I ordered the new rim. :lol: Hindsight.

I checked the spoke tension before i disassembled the wheel and they were all around 120 (about 21 on that park gauge for 1.7mm spokes)

Laced it up and now I'm at the point where the wheel is pretty evenly tensioned all around, dished right and pretty true all around (not perfect yet but certainly in the ball park) and there is a noticeable "hop" in the wheel, so that is my next area of focus is to eliminate that and then finish truing.

The wheel deflects downward at about 3 o'clock and the upward deflection is at about 6 o'clock, so they are not on opposite sides of the wheel. I guess that surprised me a little bit. I don't have a run out gauge but the difference between the high and low points seems to be pretty large, like 5mm or so. I can't live with that!

so the solution according to Sheldon (and my brandt book) is to loosen the spokes near the low point and tighten them near the high point but I though I would ask one of you savants what I should expect to see as a result of that - since the tensions are good all around will that leave me with a section of lower tensioned spokes when I'm done? Is that acceptable?

I think its better to eliminate the hop before achieving substantial tension, I'd back them all off and start over.

radial true should be done at the early stages of tension. once the radial is set it will stay theere for the remainder of the build for the most part. i would loosen all nipple 1-2 turns and redo the radial true

Alright - it was difficult to see the hop when the wheel was looser. I'll give it a whirl.

Not if you use a truing stand! You canhave even tension and a totally untrue wheel. True first then tension.

Oh, I have a truing stand. :) I should clarify - it was difficult to quantify the hop, it was apparent that there WAS hop. No biggie, I'll loosen it up and redo. The only other thing I have going on today is staying out of the rain and smoking a brisket.

honestly, if i had a 5mm hop in a wheel with relatively even spoke tension, i'd toss it and start with a new rim. it's probably out of round, especially so in this case, after having read the description of the hop.

Why? You can have perfectly even tension, a perfectly round rim, and still have a hop. As others have said, radial true needs to be taken care of during the early part of a build, and maintained throughout.

keep the lateral true in check but don't be super anal about it and you will see the hop better. in the early stages of tension use big turns like 1/2 or full turns

That MIGHT have been the problem.

5 mm - That's a lot! I agree with the others to de-tension and start again. I tension in stages, correcting the radial runout first and then the lateral, progressing to the next stage only when right. Are you gauging tension by feel or by measurement.

It is possible to build a perfectly tensioned wheel (however you choose to measure it) with any level of true (or lack of true) in either direction, radial or lateral. Assuming the rim is not faulty of course. That is why the truing and tensioning processes need to be performed alternately and reiteratively. Early in the process the emphasis is on true, and having relatively even tensions just provdes a reference for undertanding the size of the changes being made. Later on the emphasis changes to even and proper level of tension. Then finally you switch back to ultimate true as the final adjustment.

My method, after lacing the wheel, is to put my thumb nail into the last spoke thread and tighten the nipple until my thumbnail stops it. That way I know all of the spokes are starting in the same place. Then I count turns on the nipples while I gradually built tension into the wheel. Since I start in the same place and tighten each nipple an equal amount, the rim should stay round.

Your fancy-boy wheel with 24 straight pull spokes will demand some extra attention to be sure that you're actually tightening each nipple an equal amount and not just spinning the spokes, some more than others.

+1

Getting radial right requires starting with it right.

I use a HF dial indicator on a magnetic base with my home built trueing stand. My wheels are ±.010" (0.25mm) radial and ±.003" (0.08mm) axial (side to side); much better than the tire manufacturers hold. My favorite rims are Velocity Dyad and Aerohead because they are round and square, so easy and fast to build.

Sorry Grouch, but your method is BS. Hey, I do it too, but I know it is not going to give me anywhere near round wheels, laterally true wheels, or even tensions. Not even as a starting point. The variation in spoke lengths, rim diameters around the circle, etc. make such an automated approach almost useless. I just do it, because I have to start somewhere. So I don't say don't do it, just understand the limitations of the method.

That's fine, but the dial gauge is totally unnecessary. Even the simplest of truing stands provides an indicator for roundness. No, it doesn't provide numerical information, but it tells you when you are hopping or dipping. Reiterative corrections around the wheel will round it out so that you can barely see any daylight between the indicator and the rim as it spins without touching. And even a tiny hop is visible. Nothing wrong with the gauge, just saying it isn't necessary at all. Not like a spoke tensiometer anyway!

Hey, if you think Velocity rims are round and flat, you gotta try Kinlin. I find Velocity to be horrible in comparison.

Uh - what, exactly are you saying? First you say it's BS, then you say "I don't say don't do it, just understand the limitations of the method." What is your point? Don't tell us what's wrong, tell us the method that you've found so much better.

I'm saying that you can do it, but it won't give you a wheel that starts remotely true or evenly tensioned. But since you have to start somewhere, why not. The BS is in giving too much credit to the method. I know of no way what will start you off true and evenly tensioned.

Grouch, please accept my apology. I shouldn't have said BS but rather just that I disagreed with the efficacy of the method. There was no reason for me to characterize your opinion that way. Sorry.

Even a 2.5mm difference from round (assuming the high and low are equally far off) is too much for a fairly evenly tensioned wheel. I would consider that rim to be defective.

FWIW, I once built a 40 spoke tandem wheel using a Hadley hub, Dyad rim and Alpine spokes that required no final truing at all. None. That obviously doesn't happen all the time, but it happened once. I think that speaks pretty well to my wheel building method.

I would agree with you if the rim started out that way before lacing the spokes. But a hop or dip of 2.5 mm once the lacing has been done and the preliminary tension applied could easily just be due to errors made in the early part of the process that will be ironed out as the truing and tensioning continues. It is not necessarily due to an initial defect in the rim. The real way to tell is how easily the wheel comes to final true and balanced tension. If it all smooths out easily, then there wasn't much wrong with the rim to begin with. The most troubling rim defects are the ones that need big spikes in tension to pull into shape like you sometimes have at the joint/seam.

So you started at the base of the threads as you described above and tensioned the wheel with equal numbers of turns at every spoke. And without changing the numbers of turns applied to each spoke in the slightest, when you had the average tension you wanted, the wheel was essentially perfect (in other words within expected tolerances) with regard to tension balance from spoke to spoke and lateral and radial true. Including any changes due to spoke stress-relieving, adjustment of the spoke line from hub to rim, spoke windup, etc. That is an amazing story. One in a million at least. Amazing!

That exact issue has been a headache for me - the spokes spin freely. I guess I don't have to worry about windup but it's also difficult to ensure all spokes get turned the same amount as I turn the spoke wrench. I put some old innertube around the jaws of some linesman pliers and I'm using that to keep the spokes as still as I can while turning the nipples.

The other wheel in that set came out almost as good but I did have to tweak a few spokes to make it true. When I got close I used a tensiometer to make sure all of the tensions were equal. I suspect that the relatively heavy duty rim flexes less than some others might and the relatively heavy duty spokes wind up less.