The rim on my rear wheel (a Mavic Ksyrium Elite) got a nice dent and bulge this evening from hitting a large chunk of metal that was lying in the road. The chunk of metal punctured my tire first, which instantly deflated the tire, and then the rim landed with a thud further up on the piece of metal. It isn't cracked. I had my LBS look at it and they think it is still okay to ride, but it got me wondering how big would a dent have to be before it would be necessary to replace the rim.

Thoughts? At what point would you decide to replace a rim because of a dent?

I'm the last guy to recommend an unnecessary replacement, but I'm amazed the bike shop didn't advise you change it.

I'd replace the rim for almost any dent... show us a pic.

Take this from someone who was cursed with dented rims for most of his 40 year riding career. Every time I had new wheels I dealt with the worry of when and how the dent would come. Usually it would be a rain filled pothole that I didn't see or the other favorite culprit, a railroad crossing.

Anyway there's lots of latitude about what's OK and what isn't, but here are two main considerations.

1 - do the sides bulge and cause pulsing when you brake? This must be fixed otherwise you'll have poor brake modulation and risk the wheel locking in an emergency stop. A decent mechanic can get it reasonably smooth again with a hammer and file, or at least down to a tiny pulse which wears smooth over time.

2- do you feel the hop (or drop) with every revolution as you ride? What's acceptable here is strictly up to you. If it's slight and doesn't give you migraines, no problem. Or, if worse, it might get to you over time, motivating you to shell out the dough for a rebuild. (then you can be like me and wonder how long your luck will hold out this time)

Here are some pictures. The mechanics recommendation was that I use a crescent wrench to bend the aluminum back into place, and then use a file and some sandpaper to smooth it over.

It'll never be perfect again, but with a few minutes of skilled "blacksmithing" it could be so good that you forget it's ever been dented (unless you look).

I wouldn't ride it as is, so if you have good hands tap it back out, otherwise ask the folks at the LBS if they have someone who can fix it.

BTW - every once in a while the rims crack as you're taking the dent out, if that happens, you gave it your best shot, and now need to buy new.

That is dead meat on a stick. Get it replaced.

I tried to straighten a dented rim that was no where near that far gone and had no luck at all getting it leveled to my own standards. I tried about three times and gave up.

I'm fussy about how my wheels ride and my brakes feel. The constant pulsing while riding and more noticable pulsing while braking over the month or more of messing with it drove me nuts.

Mind you my rim was a medium depth V section and the bend went into the triangular V area. Nothing I did with the tools I have available would have gotten the kink out of that locked in box section. All I was left with was messing around with the portion that formed the tire channel. And whatever I did was not enough. As the saying goes YMMV but frankly I suspect you'll never get this rim to feel right. And certainly not without a lot of "autobody reforming" to the metal to straighten it up as much as practical.

Replacing it is always an option, and he doesn't give that up if he tries to salvage it first.

I've seen much worse made to ride (but not look) as good as new. In short he has nothing to lose by trying to save it, except possibly destroying it when it might have been saved by a more skillful craftsman.

The absolutely worst possible outcome is having to replace it, which is where you're starting out in the first place. If nothing else, he can use it to hone his skills before replacing it. Who knows he might dent the next one, though not as badly and the practice will have stood him some good.

I've bent it back now, but it isn't perfect. The inside lip of the rim that holds the tire's bead is a little misshapen. I'll try riding on it and seeing whether it pulses. I had been considering purchasing new wheels before this happened, so perhaps this will just spur me to do that.

Normally using the crescent wrench with a little e-tape does the trick just fine - rough stuff will remain.

However, judging from that last photo - you can see that the damage made its way all the way down to and past the rim seat into the body of the rim itself. Basically you hit hard enough to start a buckle of the rim...but it ended there.

My advice...the rim is compromised...rideable...but compromised. Start a budget for a new purchase in the meantime...this old rim can be kept as a 911 backup in the closet - quick ride, spare spokes, etc...

=8-)

I'm with mrrabbit on this one. I would definitely replace the rim as soon as possible. From the first picture it appears there may be a small crack developing in the bead seat. From the last picture it appears that the rim is bent all the way through, the wheel is no longer round and never will be.
I'm not sure you can buy just the rim, you may have to buy a new wheel.
Sorry for your loss.

i would keep working at it until you decide it is satisfactory or not. you should be mostly concerned about the lip holding the tire on.

I fixed a similar dent with a crescent wrench and file and didn't have any problems. Of course, that was a much beefier 36-spoke touring wheel. I still would take the approach of "try it and see" suggested by a couple posters. Good luck.

Yep, I think mrrabbit has it.

I wouldn't throw it away, but I wouldn't ride it everyday either.