Originally Posted by stillcovalent
What makes a wheel out of true? Does it depend on riding styles, aggresiveness, equipment, type of impact etc etc?
does keeping your tire inflated to the recommended PSI value help keep the wheel true for a longer period of time?
While getting hit by an SUV or hitting a spoke with a polo mallet, or even hitting potholes can cause a wheel to go out of true, the real
® mechanism for a wheel going out of true is the same as a bolt unscrewing under tension and vibration. The bike's spokes are really just long bolts with a nut at the end of them. If the nut...spoke nipple, in the case... isn't under enough tension or if the nut doesn't have something on it to keep it from moving, vibration will cause the spoke nipple to move.
Since the tension on each spoke is very, very high and the tension is balanced between all the spokes of the wheel, even a small movement of one spoke nipple can case the rim to move. The direction depends on the spoke and it's relationship to the other spokes around it.
Another part of the relationship is due to the nature of the fastener. Since the spoke is a very thin diameter bolt that is very long, it can flex and bend with use. When new, the spokes are bending to conform to all of the stresses that the wheel has to take during normal use. The spoke bends to conform around the hub and to settle into equilibrium with the other spokes of the wheel. These can cause a change in tension on the spoke nipple. If the changes are uneven...and they almost always are uneven..., the spokes with end up with uneven tension and the wheel won't be true anymore.
Another mechanisms is spoke twist. If the spokes had a little twist to them when they were tensioned during the build, riding...with it's constant loading and unloading of the spoke...will relieve the twist. Some spokes might end up tighter and others looser and the wheel will be untrue.
Tire pressure probably has the least effect on whether or not a wheel remains true. Riding style and impacts have more effect but probably not as much as you think. The build and attention to early maintenance of the wheel has the most effect on whether or not a wheel stays true long term.