gearhead82

I built my first wheel last week. It went great and I even had the lbs check it out for me before riding on it. They said it looked and felt perfect.

After a few rides I decided to check the spokes and trueness of the wheel. It seemed to have a little bit of runout and a couple loose-ish spokes, which surprised me. I took the wheel off the bike and deflated/removed the tire to make truing a bit easier. I put it in my truing stand and everything seemed perfect. Tight spokes. Almost no runout. I made no adjustments. Confused, I remounted/inflated the tire and put it back on the bike. Now I'm feeling loose spokes again.

Is it normal for the tire pressure to have a noticeable effect on the spoke tension? Is it standard practice to true wheels only with the tire mounted and inflated?

Rims are Velocity Chukker 36h and tires are 32c Gatorskins at about 90psi.

RISKDR1

I prefer tire off. It gives me better view of the rim against the truing stand reference parts. Also, sometimes the tire does not mount in perfect register with the rim.

xenologer

true with tires off, how else to check radial true? inflation shouldn't affect unless spokes too loose

WrightVanCleve

I've had my rear wheel out of dish after inflating the tire. I hadn't really thought about it till my last build. I've always had trouble getting dish correct on the rear, but when building it, it is almost perfectly dished. Then I did some research, didn't have net access as a resource years ago when learning, and found out that the pressure from inflating the tire can screw up the dish. I tested it and sure enough, in the stand without inflating, dished almost perfect to within a millimeter, after inflating about a centimeter off toward drive side. I do have a difficult time getting the rear right.

Now I factor in inflation before I feel the wheel is done. I think my next wheel will go better.

I build and true with tire off. Once built, if I'm just touching up the true, I'll keep the tire on.

I do wish I had net access when I was learning. I found out several things that my friend teaching me didn't mention. Last build was the first in quite some time so I decided to brush up and understand how a lot better than before. Even though the last wheel was still a bit out of dish when inflating the tire, I understand why and brushing up helped turn out a much better wheel over all compared to previous builds.

gearhead82

Ok, so I put the wheel on the truing stand with the tire installed and inflated (I'm using one of those Feedback Sports 1-sided stands). It was still true and dished properly. A couple of the non-drive side spokes just seemed a little on the loose side compared to when the tire was dismounted. I tightened ALL the spokes about 1 full turn and re-dished/trued the wheel. I'll check it out again next week after a few more rides.

FBinNY 

Yes, the tire's air pressure compresses the rim. The amount of compression depends on the rim and tire width and the tire pressure, but it can be significant. Standard guidelines for spoke tension factor this effect in, and you would have no reason to notice.

I suspect that your wheels were inadequately tensioned, especially the left side rear, so the pressure related compression created the slack you're feeling.

fietsbob

If you know the spoke is not too long, it wont puncture through the rim strip.
(one reason to take off the tire. before starting)

even mass produced wheels have gotten better in that regard..

Astrozombie

How about just deflated?

pdlamb

+1

Also, even if the spokes seem OK when the tires go on, they can unwind if they're not adquately tensioned. A few miles down the road and it'll be time to re-re-true.

Bill Kapaun

IF I'm truing a rim for the first time, I definitely remove the tire to check for hop and what I call wallow". Where the rim has flared in or out from hitting a curb. "Wallow" can be symmetrical if hit from straight on or asymmetrical if hit at an angle.
This especially important to know if you have a "one finger" stand, else you can really start chasing your tail.

davidad

Did you use a tension meter to build the wheel? 32 to 36 drive side spokes need 100 to 110kg of tension. Fewer spokes, more tension.

gearhead82

No tension meter.

If anything, I was afraid I had over-tensioned the spokes when I built the wheel, which is why I had the LBS check it out for me. My 36 spokes felt quite a bit tighter than a set of 32 spoke wheels I was comparing them to.

Either way, ALL of the spokes feel looser after a week of riding on them, which was exacerbated with the inflated tire. I think FBinNY is correct that the spokes were loose, otherwise I probably never would have noticed the difference with the inflated tire. I just don't think they started out loose though. I just need to diagnose whether they just got loose due to a little bit of stress relieving, or if the nipples actually backed off a little and need some loctite. I'll know more after a few more rides.

seely

What did you use for spoke prep?

robert schlatte

If the spokes are loose with the tire inflated, leave the tire on and inflated and bring the spokes up to adequate tension.

fietsbob

Double wall rim and a stiff rim strip & there is no tire-tube to spoke nip-head contact.

gearhead82

I used a little bit of nickel anti-seize on the spoke threads and a dab of grease where the nipple seats in the rim.

The rims are something like 32mm deep and I'm using plastic Veloplugs instead of tape so I'm in absolutely no danger of a spoke poking the tube while truing with the tire installed.

mconlonx 

I build wheels without tires mounted, but will true new bike wheels or tune up bike wheels with tire installed.

cycle_maven

I like to use a little boiled linseed oil as spoke prep- it will harden somewhat after a couple of days but until then it acts as a lubricant while truing. I wouldn't use anti-seize as spoke prep. But I've never had mounting a tire change a wheel I've built in any measurable way, either.

bike_forever

Minor tweaking is OK with the tires on!

seely

Boiled linseed oil is a pretty decent choice. I would second the recommendation to not use anti-seize. We use something similar to a blue Locktite, but for a beginner wheel builder it might setup too fast. There's roughly a 1 hour working time frame before it starts to set.

davidad

Anti seize or grease or oil is fine if the tension is high enough. When it is low and the bottom spoke is loaded the spoke becomes loose and the nipple can back out. Don't ask me how I know that!

dweenk 

Truing off, tweaking on.

GravelMN

I don't build a lot of wheels, but the few I have I've always trued and tensioned them tire off, then retrued and tensioned with the tire on at normal inflation. It usually doesn't take much tweaking after the tire is on, but I'm kinda OCD and feel better knowing that the wheel is true and properly tensioned on the bike, not just on the stand.

jyl

This thread made me curious. I did a quickie check. I deflated the tubular tire on one wheel, measured tension on a DS and a NDS spoke, then inflated to 140 psi and re-measured tension on the same spokes. There was no measurable difference - due to the precision limits of the Park TM-1 tool and my crappy eyes, I cannot rule out a 5 Kgf change but think I can rule out a 10 Kgf change. This is a low-tension wheel, DS is 95-100 Kgf and NDS is 70-80 Kgf (Fiamme Ergal on old Campagnolo high flange hub, DB spoke w/ 1.6mm center section).