WyoRider

Strange problem that won't seem to go away and no help from the good & competent folks at the LBS. I have Mavic CXP 23 rims with basic stainless spokes. Problem is, every few rides one of the little buggers unthreads itself. Maybe 300 miles, max, and one of them will go. I keep track of them with marker and it is not always the same one. Always the rear tire.

Some solutions I've tried:
- re-true wheel (twice). basically slacked them off and went through the process of tightening them back down.
- add some loc-tite. I know, not the preferred solution but this is driving me nuts.
- check the spokes every couple rides. This is the tried and true method but is there another fix?

Some more info:
Cannondale R1000
Ultegra 9 hub
my weight's running about 190 (overweight issue on the wheelset??)
original plastic style rim tape still on there - I am suspicious

Cheers & thanks

AndrewP

Uneven tension and not enough tension. Get a Park tensiometer - cheap at $50 considering the hassle it will save you. Dont forget to stress relieve the spokes after trueing.

supcom

Assuming the wheel is properly tensioned to begin with, I would replace the spokes and nipples. Perhaps these are cheap or from different manufacturers and not quite compatible? Get quality spokes and nipples from the same manufacturer and use them instead. I suspect that the spoke threads are slightly small for the nipple threads.

Good spokes/nipples properly tensioned do not back out after a few hundred (or thousand) miles. Loctite is not needed to build a wheel.

The bike frame has no bearing on this. The hub is not a player. You are not overweight for the wheels. The rim tape has nothing to do with the problem although I would use Velox tape after respoking the wheel because it's the right thing to do..

WyoRider

Thanks for the point about a tensiometer - basically I've been working at it by feel and true but this may be getting a bit uneven and incorrect (as indicated by the next posting). Cheers

WyoRider

I was contemplating the spoke/nipple replacement approach but didn't really want to take on the task of re-building. Well it is winter now and I'll have some time coming up to set up the stand. Might as well admit a bit of hopefulness/laziness on this one.

Sentinal5

Is this a stock wheel? If not, are you sure that you have the right size spoke and nipple (1.8 or 2.0). I have been building wheels for a well over 10 years and I agree with the other guys that you need to check the tension on your spokes when you replace them. While you don't need loctite, I have found that Honda ProLock 1 (blue bottle) works very well for building wheels. If you are on a budget, you can use a "paste" type toothpaste! Don't use the gel types. lightly coat the spoke threads and lace it up!

DannoXYZ 

Doing it by feel typically leaves you about 20-25% too loose most of the time. Once tension gets up to 100 kgf, it's really, really hard to tell the difference between that and anything higher. You'd want to be around 120-130 kgf on that wheel.

Also get double-butted spokes with the new rebuild. They stretch more before losing tension and will give a longer-lasting wheel. And blue loctite's is about perfect for holding the nipples in place, not too tight and not too loose. A lot of shop will use the wicking loctite to add it after-the-fact.

WyoRider

OK thanks everybody for weighing in - I have moved towards getting some double-butted spokes and will move on to a re-build of the wheels. This will be my first wheel build so I appreciate the advice for sure. With any luck the Wyoming roads will get clear of snow every now and then this winter and I can try them out on pavement instead of being stuck on the trainer.

77Univega

--- Try plucking the spokes as you increase the tension.
Here is a quote from Bicycling Magazine's book entitled Complete Guide to Upgrading Your Bike by Frank J. Berto, page 226:So I just checked my own spokes and sure 'nuff, G# above middle C is the most consistent pitch.

mechBgon

Linseed oil is another old favorite for lube-&-lock on the spoke threads. It sets up gummy after a couple weeks. Boiled linseed oil sets faster.

Using musical pitch in combination with true and roundness can help you even out the spoke tension among spokes on a given side of a rear wheel, or both sides of a symmetrical wheel. I have a couple of tensiometers and use them to gauge the approximate tension level of the wheel as a whole, but for evening out tension among spokes, frankly I find that my ears have better "resolution." But people all develop their own style and technique after building lots of wheels, so whatever works.

Note that musical pitch in absolute terms isn't a good way of measuring tension. The same tension will produce a higher pitch on a thinner spoke, and will produce a higher pitch on a spoke made of a lighter material (titanium being the chief example). So G# above middle C could result in much different spoke tension on DT Revolutions than it would on straight 15-gauge spokes, for example.

77Univega

--- Yes, that makes sense. So I searched out John Allen's web page entitled "CHECK SPOKE TENSION BY EAR" and he expands on his technique of using musical pitch to measure spoke tension:
www.bikexprt.com/bicycle/tension.htm#pitchtable

Avalanche325

I had the same problem on my MTB rear once. It was a couple stripped nipples (sounds painful ). I replaced them, retensioned the whole wheel, and all was good.