After getting off work today and starting to ride home I noticed that my front wheel was severely out of true in more than one spot - about 2cm deflections each way! I'm not certain how it happened, but I suspect someone screwed with my bike. I'm quite certain I would have noticed the problem on the way to work, and I didn't take any especially hard impacts. I noticed that the wheel wasn't right where I normally place it (propped onto the toe board of a handrail) - it looked like someone had moved it. Many of the spokes were very loose and I know all of them were tight as recently as a month ago. Any idea on how this could have happened? I find it hard to believe that inadvertent bumping into the bike could cause this much of a problem.

I decided I shouldn't be riding on such an out-of-true wheel and set up makeshift shop. I borrowed a coworker's 100mm adjustable wrench (I had no spoke wrench to use) and started out by tightening all of the spokes that were noticeably loose. Then I started a normal lateral truing procedure. Unfortunately the spokes I needed to tighten more couldn't be tightened any more, and I was about to give up and call my wife. Then I had an epiphany and remembered a lesson from my Zinn book: beating the rim into shape. Some say this isn't a good idea, but I decided it was worth a shot. I figured if it didn't work I'd probably be replacing the rim anyway.

I was amazed to see that this actually works. I found the worst spot, and gave it three good whacks on the wooden table. The shape improved slightly. I was pleasantly surprised to see that after doing this, I was able to tighten the spokes that needed to be tightened for truing a little more. So I repeated this over and over... where spokes couldn't be tightened further, I whacked the rim. The worst spot was around the valve stem opening, but it was almost as bad 180 degrees out, and there were one or two more other areas that got whacked. I beat the hell out of the thing, which is why I think the problem didn't occur on accident. I probably hit it on the table over 30 times.

I was quite proud of myself when I ended up with a wheel that I thought was rideable. Some more truing is definitely in order, but indeed I got home with no problems. The question is, what to do now? I see no dents, cracks, etc. on the rim - is it OK to keep using after more truing, even if I need to whack it more? I hate to replace parts that are still usable.

Cheers,
Kevin

wow. when we get a wheel in the shop with that much lateral run out, we usually recommend a new wheel or a rebuild. i have used brute force to repair wheels for clients who "just needed to get home", but that type of repair does not usually last very long, and they soon come back for a new wheel.

Yeah... I tried to get it more true today, and I was able to get it a little better, but then I noticed that many of the spokes became quite loose in the process of beating the rim some more to accomplish the truing. I also found that the rim bulges outwards a bit on each side right at the valve stem hole. I'm going to have the rim and spokes replaced, and have the shop buy or build a spare wheel at the same time, which I was already looking to procure. Too bad I didn't have it already!

BTW, sorry for the double post... I don't know why, but lately whenever I post a message it often makes a double.

What I have done, on wheels for my own usage, (or for people fully briefed on the situation) is to unlace the rim, manually bend it back into flat, and then lace it up again.
In theory this would leave you with a rim that's weaker than before, but IRL I've had no more trouble from these resurrected rims than I've had from any other rim. I haven't taken them touring or DH-ing, but they seem to hold up well for service on beater bikes.
YMMV though, so do it at your own risk. Any signs of cracks and wrinkles, scrap it.

Does not sound like normal use would cause such problems.. Yesterday , on a group ride we had a minor accident. I was behind a friend and he purposely ran into the back of a car when the motorists opened the door and he choose to run into the back of a car instead of hitting her being 'doored,'. He slowed down considerable by braking but the impact was pretty hard.. The crash destroyed the lens on her rear turning light. Looked to me like he started to go over the car , but his chest hit the window in a way that prevented him from being flipped over the car..
The only problem with his bike is he needed to tighten his steering tube.. I was totally surprised that some wheel damage didn't result because the wheel hit hard..
. Any idea who would do such a thing.. . ? Rims are too critical, I'd not trust it..
Besides a handrail. Was it outside. ? Maybe a car backed into it ?.

I'm almost positive it happened while the bike was locked up. I would have noticed it on the way in - it was bad enough to feel vibrations. I do ride over a few RR tracks that are pretty rough, but I take them slowly, and I find it hard to believe the wheel could have gone from being in true to having 2cm deviations riding over them in one day anyway (I've been doing so for awhile). My best guess is that someone grabbed the handlebars and turned the wheel into the handrail with a lot of force (or repeatedly). The two bends in the rim are 180 degrees apart. The bike wasn't in anyone's way. it was inside where no cars could get to.

People are a bunch of *******, you know? Nobody would do that if I was around.

Bike racks that have slots for holding the wheel can do this sort of damage when someone bumps the bike.

I don't think so, I believe that the stem would shift before the wheel would take any damage that way. But some bike racks will easily do that kind of damage if the bike is toppled over, either accidentally or deliberately.
If the bike was upright when you found it I'd go with the accident theory. It's not even certain that the person who knocked your bike over knew that it had suffered any significant damage.
But if you found it on the side I'd go with deliberate vandalism, it's all too common. Maybe not during a regular week day, but Fridday/Saturday evening/night - sure.

Well, that's what happens when the load on a wheel becomes more than the rim can take, it warps into a taco/saddle shape, which relaxes the spokes. You can get there by simply increasing the spoke tension a tad too much. It's actually an old wheel building tip to take the tension up to where the rim begins to warp, then back off just enough to get it back to true. These days its gone out of fashion, because it's suspected to cause more than its fair share of cracks around the spoke holes. If not spoke tension then any other source of force, hike a good hit/bending can also cause this.

Wheels are immensely strong when they see a "clean" load (ie straight through the plane of the wheel) particularly symmetrical ones like a front.
I've seen impacts that's bent forks to the point where the wheel has no longer cleared the down tube, and the wheel has been perfectly fine.
The point of collapse for a static wheel I've seen quoted as being somewhere around or above 300 kilos.

Thanks for the information. FWIW, the bike was locked with a chain around the top-tube, so I doubt it was knocked over. I don't think it can be knocked over. I do believe you about the stem shifting first - I was thinking the same thing.

But I still don't have a better explanation. I'm almost positive the wheel was absolutely fine before this - and even if it did happen while I was riding and I didn't notice then, which I highly doubt, is it possible that a rim could suddenly bend 2cm from hitting something? I hadn't tightened any of the spokes in weeks. I didn't ride any differently.

I took it to the LBS today, and they replaced the wheel while I waited, re-using the exisitng tire, tube, (snap-on) rim tape, and disc brake rotor. They split a wheel set with me, saying most people trash the rear so they'd sell me just the front. $60 for the wheel and $6 labor. Made my day, and I asked them to rebuild the original wheel with a new rim (and hopefully spokes) so I'll have the spare front wheel I was looking to get.

LBS said it was vandalism. They also said I might have been able to get the wheel true without whacking it by loosening the spokes on the same side as the deviation after tightening the spokes on the opposite side of the deviation - I had not thought of that at the time. Live and learn.

I think it's time to get one of those spoke tension meters, even if I don't plan on building wheels. Here's a question: if a spoke's tension is at spec. but it needs to be adjusted for truing, what do you do? Does being true have preference over being properly tensioned, or vice-versa? Or do the two usually go hand-in-hand? In other words, how does one balance being true with being properly tensioned?

Then the most probable cause is vandalism. There are plenty of ways to damage a wheel if that is your intention. I've seen a guy taco his front accidentally once. He'd been stradding the bike, rocking the bike back&forth against a locked front brake as to check for headset play. Then he repeated the exercise, but now with the wheel at a 90 deg angle to the frame.

IMO, not w/o spilling the rider. Wheels are really strong laterally, so apart from snakebite punctures and low spots you pretty much have to hit them at an angle to do damage.

Well, kinda-sorta. Loosening on one side and tightening on the other is pretty much the definition on how to true a wheel. But if you started out with a decently tensioned wheel, which then takes a hit bad enough to bend the rim - then the spokes on the convex side of the deviation will be fairly slack already to begin with. Slacking them even further might get you true, but is unlikely to give a lasting result.

If tensions are OK, and the rim straight, then tensions are maintained by performing an equal amount of increases and decreases. Basically if you tension one spoke a half turn, then you de-tension its neighboring spoke with a half turn as well.

For durability purposes tension have preference over true, but it has to be balanced against brake performance and ride characteristics. A badly untrue rim braked wheel will eventually brake and ride poorly, at which point it's time to give some priority to trueness instead. If it's not rideable it really doesn't matter how durable it is...

A rim that's straight to begin with, and a decent builder - then trued & tensioned will go hand-in hand. Poor build on good material, or average build on poor material - then the results can be anything.

Pretty much up to mechanics preferences and rider requests. For a disc-brake MTB ridden on trails true is not critical, so preference can be given to tension. For a road bike with narrow clearances true can become a limiting factor.