peripatetic

I've been re-dishing and re-truing my 27" rear wheel on a ss conversion. Re-dishing went fine, but as soon as I started to true the wheel, I got a few stripped nipples. So I went and got replacements, came back, managed to get most of the wheel true, then some of the nipples (incl. the new ones) were too tight and got stripped as I attempted to improve the roundness of the wheel. From tightening the spokes, I decided that I couldn't tighten anything much further, and the thing seemed good enough as is. About 1/2 hour after I put the wheel back on the bike with rim tape, tube and tire, I heard the dreadful "pssssssssssssssssssssssss," and watched the thing go flat. It happened right at one of the nipples next to the valve--I could feel the air escaping through the nipple--so I figure that the spoke was overtight and sticking through the tube.

Anyone tell me how to correct my strategy to avoid overtightening things but still get the wheel true and round? Do I need to loosen all the spokes before I start truing/rounding? If so, how loose should I go? I don't have spoke prep, but I used a little grease on the nipples I replaced after reading an entry about this in the archives.

DiegoFrogs

If you don't have access to a spoke tensiometer to measure the tension non-subjectively, you should "feel" the tension in the spokes of a good wheel. You probably overtensioned the spokes. I've rounded off a few old nipples, but I've never "stripped" the threads.

I guess the answer to your question is that you don't always need to lower the tension in your spokes as the first step. To actually start you need to gauge the tension in the spokes, either qualitatively by comparison or numerically by measurement. Then you need to decide what tension would be appropriate. Adjust as necessary.

Retro Grouch 

You're probably not going to like hearing this but my guess is that your spokes are too long.

Without looking at your bike, I'm guessing that in the process of redishing your wheel you have run out of spoke threads on one side. That would account for having so much trouble tightening the nipples and causing several of them to round out. Too long spokes would also account for a spoke projecting through the rim strip and puncturing your tube.

peripatetic

RG, you're right, I don't like reading it. But you make sense. I just got the wheel fairly true, though I guess I really should get a tensiometer. About 1mm or less of wobble or roundness variation is probably okay for a round-town beater, no? The wheel's nothing special, I just don't want it to rub against the pads.

I didn't strip any threads, just rounded some nipples, BTW.

I think the flat was actually caused by my impatience at putting on the tube/tire--there was a small pinched section where the tube popped.

While I'm posting, anyone recommend a decent, reliable and low- or lower-cost tensiometer?

phidauex

Seems like you've got things worked out..

Typically what I do on old wheels is drip some lube on all the nipples after removing the tire, tube and rim tape, then wait a day. Then I back out all the spokes a few turns, and then begin my dishing and retensioning. It sounds like overly-tight spokes to me.. If a few of your spokes are too long, and they start to protrude from the nipple, just hit them with a grinder, dremel, or even just a flat file to shorten them a bit. As long as they aren't so over-long that you run out of threads at the nipple end, you'll be fine.

Good luck!

peace,
sam

peripatetic

Uh, nevermind about the tensiometer. Don't think I have the dough for something like that.

Sam, thanks for the tips, esp. re: filing the spoke and the pre-lube. I was wondering if there was a quick, available alternative to spoke prep.

Just wondering: are the spokes on a regular 5/6/7-sp. freewheeled wheel longer on the non-driveside to begin with? Or does the wheelbuilder always begin with the same length spokes? Now that I've re-dished, even though the wheel is centered, it seems like the drive-side spokes are lower tension than the non-drive-side spokes...

DannoXYZ 

Uh... you do know that you need to tighten/loosen spokes in pairs right? If you want to move the rim to the right, you tighten the right-pulling spoke by 1/2 turn and loose the adjacent left-pulling spoke by 1/2 a turn. This preserves the same overall tension on the rim. Or else you'll end up with a wheel that gets tighter and tighter as you true.

peripatetic

Yeah, I know about that. Thanks for checking, though.

The wheel's come out fine--newly centered and re-trued. I find the main problem occurs when I'm trying to get it rounder; I started to loosen some of the tighter spots instead of tightening the looser spots. It was weird, though: I had this one spoke that kept needing to be tightened, I even had replaced the nipple, but the adjacent spokes (on the opposite sides) were getting really loose. I got the spot close to decent, then just left it alone, rather than risk rounding that nipple, also. That spot still didn't feel quite right, though...

DannoXYZ 

" I had this one spoke that kept needing to be tightened, I even had replaced the nipple, but the adjacent spokes (on the opposite sides) were getting really loose. "

Sounds like you've got an S-bend curve in the rim...

dbg

Are you possibly reducing the "dish" when converting a multispeed rear to single-speed. If so you'll end up with drive side spokes too short and non-drive side too long. Just a thought.

Also the last time I had nipples stripping the threads I discovered a few larger guage nipples had slipped into the wrong bin.