Re: [CR] First aid/replacement for a rim?

(Example: Production Builders:Frejus)

To: <classicrendezvous@bikelist.org>
Date: Wed, 3 Jun 2009 13:06:35 -0700
From: donald gillies <gillies@ece.ubc.ca>
Cc: marcus.e.helman@gm.com
Subject: Re: [CR] First aid/replacement for a rim?


I hope this is a 36-spoke wheel. If it's a 28-spoke wheel it will be much harder to get this wheel working perfectly.

I have a similar troublesome wheel (Mavic GEL 330), which weighs almost exactly what your rim weighs, about 330-350 grams. I think part of the problem is rider weight (200-220 lbs), the rim is really too light for frequent use with a heavy rider. A 330 gram rim is more for racing or for an 180 lbs or less rider. I experienced a total loosening of all the spokes on my wheel on one club ride, after it was trued at a very good LBS just a week or two earlier.

I finally got a broken spoke. The spoke was making a noise that i could not find, until it broke. I de-laced the wheel, added 9 new spokes, picked the best of the remaining 35 spokes, and heavily greased the nipples and nipple ferrules on the rim to get a tight seal when relacing my GEL 330 rim. Part of your problem could be bent/stressed spokes or nipples that don't turn freely (hence twisting the spokes), so if you plan to re-use old spokes, make sure to replace several of the worst and don't reuse any that have dings near the heads.

If your wheel is out-of-round, your only choice imho is to de-spoke the wheel and 'bend it round'. Fixing an out-of-round wheel with spoke tensioning is VERY difficult. top-end shops used to have a wire-puller device that could put a wire on the rim and then with a set of metal arms pressing on the rim, tighten the wire to pull out "blips" in a rim, or straighten dented tubes on a bike, in the same way. I am not experienced with fixing out-of-round rims in a home shop but you can probably find it in a high-end bike mechanics book or on the web. Use a NOS rim to compare with your used rim.

The rim should also be straight side-side. Fixing wobbling rims with the spokes is MODERATELY difficult. Once the spokes are off, lay the wheel on a very flat floor. If it rises up more than 1-2mm anywhere, you will also want to try flattening it so that it's very close to straight.

Once the rim is round and straight, you have a CHANCE of getting it true with even and tight spoke tensioning. Having tight tension is critical to having it STAY tensioned so grease or nipple prep is critical in respoking this rim.

By the way, if you have a heat-treated rim, there is NO CHANCE of straightening it once it's out of round or has a bad wobble, so in my opinion you should just throw away heat-treated rims and start with an untreated rim. Luckily, not many of these are sold any more.

- Don Gillies
San Diego, CA, uSA