Bicycle Mechanics - wheel truing
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08-01-02, 01:48 PM
I have bontrager race lite wheels on my road bike and want to try truing them myself. The problem is I have never trued wheels before (don't even own a truing stand yet). The wheels have 20/24 spokes. Is truing wheels with that many spokes different/harder than truing wheels with a regular number of spokes? Am I likely to destroy them and is it better to let the LBS do it?
I can't comment on how the number of spokes will affect the truing procedure but I would guess that it wouldn't be much different. Truing is pretty easy and you don't even need a truing stand for it. I just leave the wheels on the bike and flip it upside down. I use the brake pads as guides for lateral truing. You don't even need to remove tires for lateral truing. Roundness truing is probably a little harder since you have to remove tires and mount some kind of reference point to the frame.
This method may not give you a perfect truing job but it will be close enough. How long would a perfectly trued wheels stay perfect anyway?
08-01-02, 02:26 PM
I am not totally sure about your situation. But in mtb with either 32 or 36 spoke options it is FAR easier to true a 36 spoke wheel than a 32. When one spoke blows or even becomes loose the affect is negligable on the one with the higher spoke count. Thereby making it easier to return to original position. (
I refuse to buy reduced-spoke-count wheels because there is no way to true them accurately. The higher the spoke count, the more reliable and more repairable/maintainable the wheel, and the better its strength-to-weight ratio. I currently own 36-spoke wheels exclusively and will insist on at least 32 whenever I buy wheelgoods in the future.
In regards to attempting to true these wheels, let me give you a wheelbuilder's point of view.
First, any low spoke count wheel will be harder to true, and paired spoke wheels, like the Bontrager, are even more difficult. The problem is that each spoke carries a higher percentage of the load. If the rim is even slightly bent, it will be impossible to true.
Another problem with these types of wheels is that a spoke failure, especially on the rear wheel (which is the likeliest place!) often results in a wheel that will not clear the brake pads even with the brake QR open! I've seen it many times as I do a lot of volunteer wrenching on rides here in Ohio. People are very upset that they cannot finish a ride due to a single broken spoke! I try to keep a few spokes with me, but these days there are so many permutations of spokes and nipples, that it's difficult to keep spares around for every conceivable failure.
So why have these wheels become so widely embraced? In my opinion, because they look cool. Pretty shallow reason, but then look at the other dubious trends in the bike manufacturing business. Also, notice how individual rim weights are never listed? Those rims are very heavy!! So often, a customer will complain about frame weight, which doesn't REALLY matter all that much ;), then buy wheels that are 200+ grams heavier than what I could have built for them. I offer a lifetime spoke breakage and truing warranty, too!!
So, back to your question...
I see self-trued wheels nearly every day. Often, they are a mess of rounded of spoke nipples, mixed tensions, and accelerated fatigue. Without a tensiometer, anything but a very minor tweak should not be attempted, especially on low spoke count wheels. Not to sound alarmist, but your safety is also at stake. I've seen one these wheels turn into a potato chip during a turn in a crit. Man, what a mess. The guy had given his wheel a "quick true" before the race, gotten the tension to high and blammo! Ruined his day, his wheel, and the skin on his left leg!!
08-02-02, 09:13 AM
Welcome to the forums, cogito! :) By the way, did you mean to say "heavier" instead of "lighter" here...
then buy wheels that are 200+ grams lighter than what I could have built for them.
Already fixed it! Thanks for the welcome!:beer:
Since we are talking about tensiometers
(or tensionmeters, whatever).
other than the $99 wheelsmith model,
although the wife hasn't objected too much
I do believe this might push it a bit.
(honestly, it really will make me a better wrench. . .
and yes I will true your wheels . . . :lol: )
I really don't see any way around buying one
of these. (I don't have perfect pitch either!)
08-02-02, 05:54 PM
Hozan makes a very expensive dial-gauge tensiometer, or they used to anyway. Wholesale on it is/was about $300. I have a Wheelsmith myself, but for a practical, affordable, easy-to-find alternative, try a Cricket automotive belt tensiometer, which you can get from a good auto-supply store. Look for tensions in the ~90kg-100kg range on driveside rear spokes. edit: let me add that you should push from the front or rear of the spoke when using the Cricket, not sideways, because if you push sideways the spoke braces against the spoke that crosses it (assuming a crossed spoke pattern).
It's not really practical to try to get all the spoke tensions on the same side of a wheel to be precisely the same, IMHO. In a perfect world, sure.
My preferred technique is to look for an area where the wheel needs truing or rounding, and then look for a spoke that's tighter than its neighbors which I can loosen to accomplish the correction, or a spoke that is looser than its neighbors which can be tightened to accomplish the correction, or one of each of these. In this way, the tension of the wheel gets more consistent as I go. Obviously, on a rear wheel I only compare the spoke to its neighbors on its side of the wheel, unless the wheel is a dishless rear wheel of some kind.
The process above needs no spoke tensiometer at all... I simply pluck the spoke and listen to the tone (one reason why I have a hard time truing wheels in a noisy environment). If the wheel is being built, I'll do some truing and rounding, stress the wheel, true and round, stress the wheel until it's staying straight and round at a given tension. Then I check tension, raise tension a bit, and repeat the procedure. Every so often I check the dish to see if I need to bias in one direction or the other.
Hope that helps! :)
Unless one is truly "tone deaf," the pitch-pluck method of spoke tensioning is acutally quite decent, and it will immediately reveal a loose spoke.
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