mlamb01

I have some new wheels, and I have a little bit of lateral out of trueness on the front wheel. Its a radial pattern, 24 hole. I took the tire off, put it on the truing stand, and equalized the tension and got the true almost perfect.

Put the tire on and pumped it up, and now I have a slight wobble. Its a brand new Conti GP4000, with around 200 miles on it. Mold lines are still on the tire...

Is there anything I can do to get the wobble out? I was thinking about truing it with the tire on and pumped up, but that just doesn't seem right. There are no visible bubbles in the tire sidewall at all, or anything that seems like a defect. Bead is centered on both sides...

AEO

it's fine, just tighten up the spokes with a fully inflated tire on the rim.
120psi tire inflated on the rim will cause spoke tension to drop, because the rim becomes compressed.

dsbrantjr

True the wheel with the tire on and inflated to working pressure.

davidad

If it doesn't rub don't worry about it.

rogerstg

It's fine for you to make some minor adjustments after the tire is on. BUT, if the adjustments are significant, your wheel tension is probably low.

hueyhoolihan

once i true them, i ride them a while (20-50 miles or so) and true again, and again, if necessary . it never even occurred to me to remove the tires.

cpt. Howdy

Every time I try to true a wheel with pressure in the tire, I break the spoke and pop the tube.

Every time.

mrrabbit 

One sign that a wheel has been overtensioned is when the wheel performs a slight s-wave wobble when the tire is inflated. If DEFLATING the tire results in the wheel returning to true or very close to it - then the wheel is overtensioned.

I would have questioned whether the rim is fatigued or not - but the note that it's a new wheel negates that possibility unless by "new" you mean "new" in terms of your ownership.

Since this is radial laced wheel, having a tensionmeter is more important...

Do you have one, and if so, what were your readings translated into KGF?

=8-)

mechBgon

It's routine to true wheels with the tire on and pumped up, go for it.

vredstein

This can happen if with single wall rims and rubber rim strips. When the tire is highly inflated, it puts a lot of pressure against the underside of the tube and the outside of the rim strip. The sharp slotted head of the nipple acts like a drill against the underside of the rim strip, boring a hole into it and through to the tube. The Not sure if this is your situation or not.

amandadun

How can you check rim tension?

fietsbob

be sure the spoke is not too long and wont poke thru the rim strip..

add up total spoke tension..
(need an accurate spoke 'tensionometer' for data collection)
..Tension against the rim, it is actually in compression ..

mlamb01

Yes, I have the Parktool TM-1. Average tension for the left and right sides without the tire on is 16.10. Don't remember exactly what that translated to in KGF, but I think it was about 130. I have the Sapim CX-Ray spokes. The wobble does appear to be a slight S-Wave. And this is a brand new rim, I have about 200 miles on it so far.

mlamb01

Yes, I have the Parktool TM-1. Average tension for the left and right sides without the tire on is 16.10. Don't remember exactly what that translated to in KGF, but I think it was about 130. I have the Sapim CX-Ray spokes. The wobble does appear to be a slight S-Wave. And this is a brand new rim, I have about 200 miles on it so far.

mlamb01

I should add that before I started tension adjusting/truing the wheel, the tension meter readings were like 15.6 and 15.9 for the left and right sides, but that was with the tire mounted and fully deflated. And intitally, one of the spokes was like 10% loose. Did not occur to me at the time that the deflated tire might still be exerting some inward pressure on the rim.

Now with the tire off, all the spokes are within 2% to 3% of each other, with one outlier being about 7% tighter.

mechBgon

How's the roundness coming out?

Kimmo 

Is that a bit on the high side?

mrrabbit 

This is a radial laced wheel. Although tension for lower count spoked front wheels will bump into the low hundreds - problem is:

Rather the rim being your limiting factor, in a radial laced wheel the hub is the limiting factor.

Sounds to me as though you are not only putting the hub at risk for flange failure - but you are overtensioning against the rim as well.

Bring the tension back down to about 105-107 kgf. (Under 110 kgf...)

True, stress relieve, if it holds, then install and inflate tube and tire.

If it still holds, then you are back in the ballpark in terms of where the wheel is supposed to be at tension-wise.

Crossing my fingers though that you haven't damaged the hub already...

=8-)

reddog3

According to the Park conversion chart, (Cx-Ray- 0.9x2.2 blade)- "16" would translate to 146 Kgf. Right on the edge of deforming the rim? Add tire pressure and the rim goes wobbly? I think maybe so. I'd back 'em all off and true and tension again.

For low spoke count fronts I've been pretty comfy at around 105-110 Kgf. I've only recently started doing a few low spoke count wheels so I don't have a ton of data. I've noticed that with tire inflation of 120 psi that tension is reduced about 5-7%. So far it all stays round and true. No post inflation tweaks required, but I keep a close eye on these wheels because they are going places they shouldn't. I resist the urge to bring the tension up after inflation.

reddog3

Right-o mrrabbit on the radial lacing. I have a couple rears out there radial laced with 8 spokes NDS. The supplier suggests that you can achieve equal tension on both sides. I can't get there and keep things in line and get "proper" dishing. I get about 90% of DS tension while keeping things real. Even at that I keep a close eye on the hub flanges. I only get to see these wheels every couple weeks but so far-so good.

mlamb01

Getting some interesting information here... Let me clarify a few things.

My Parktool tension meter, TM-1 is brand new. So it is possible the calibration would be off, and I really don't know how I could tell or adjust for this.

I've read 2 books on wheel building from Munson and Brandt, and have never built a wheel from scratch. I've trued a couple of wheels.

I run the front tire at 90 PSI, and I weight about 170.

Aluminum rim width is 23mm, and depth is 28 mm. Brand new wheel, it was bought prebuilt.

Again, before I go messing up something that does not need fixing, this lateral wobble that I am getting is maybe .5mm. Without the tire on, the wobble is probably less than .2mm. Mounting and inflating a tire seems to exagerate it. I'm getting these rough measurements by putting a feeler gauge between the rim and the gauge, when it moves the most away from the gauge.

I was expecting the wheel to come in rail straight, and it had a slight wobble. I like to have complete confidence in my bike, and I try to have everything on it as perfect as I can get it. I used the tension meter and with that I was able to improve the trueness, and get all the spokes within +/- 3% of each other, except for one that was +7%. During this process I think I ended up raising the overall tension about 5 kgf accidentally.

The info I found on the CX Ray spokes said they were 1x2.1, and to use value 22 in the chart. This is where I was getting the 137 kgf.

Which is more important? Spoke tension with the tire off, or spoke tension with the tire at riding pressure? I think at 90 PSI the tension was around 13, or 100 kgf.

If I need to lower the tension, should I just loosen all the nipples by 1/4, then recheck it?

Kimmo 

Spoke tension with the tyre at pressure, I'd say... you don't ride on bare rims. But surely it doesn't make 30kgf difference?

And even spoke tension is far more important than 0.5mm of runout. If you're gonna be anal, be anal about that compromise.

Works for me.

mlamb01

I'm at work right now, so I don't have access to the meter or the wheel to double check it. I'll recheck the inflated vs deflated later tonight. For reference, when I measure, I have the spoke horizontal, no load at all on the wheel, and hold the meter such that it is horizontal, so gravity will not affect the spring reading. I also try and get it in the center of each spoke when taking a reading.

mechBgon

Technically, you could hang a 100kg weight from a spare CX-Ray spoke and see what the TM-1 reads on its scale.

Ultimately, as long as rims, spokes and hubs are not utterly perfect and homogeneous, you'll reach a point at which you have to pick your priority and compromise a little. If it were me, I'd let the spoke tensions range a bit more, and dial in the true & round to at least ±0.1mm, which I bet you can achieve without too much trouble.

fuji86

I'd leave the rim trued as is, since you were able to true that without the tube & tire on, it's obviously a defective tire and the next tire you get may/will require you to true the wheel again. Are you able to isolate the area where the tire is defective ? If it's that bad, sell the tire and get a new one. If you can isolate the defect, snap a pic of it and post it. I'm curious just to see how lopsided it is. Maybe upload a video demonstrating the wobble ? Because if the hub is tight, rim & spokes are true, the defective tire could give the appearance it's wobbling or out of balance ? I've left truing to the LBS, but watching them do it, they true laterally & radially to the rim anyway. If the tire has a bald spot from skidding or the tire is just plain defective, there's not much you can do about that gap beyond replacing a defective tire. And with a bald spot or defect, I wouldn't want to correct the trueness of the rest of the tire to compensate for that.