Dirt Bike Rim Repair
This article was originally published in the June 2017 issue of Dirt Rider.
So you have a newer bike and your wheel hit something that caused a big dent on one side of the rim. You don’t want to buy a new rim, but you are not sure if you can fix the one you have. This repair will require an intermediate mechanical skill level. A few items you will need that not everyone has are a hydraulic press (a small one will work fine), a propane torch, and a wheel stand. The most important of these would be the hydraulic press—I would not suggest attempting this repair without one. Here are a few photos and tips of how you can make that rim look really good and save a few bucks at the same time.
1. Determine if the rim is damaged on one or both sides. Remove the tire and clean the rim thoroughly. If the rim appears to be damaged on both sides and you try to repair it, you will be left with a severe flat spot. If that is the case, it is a better idea to replace the rim.
Make sure the rim is not cracked. We would not suggest welding a rim and then trying to straighten it. If the rim is damaged to the point that it cracked, just go ahead and replace it. In this photo you can see this dent is quite big. I would say this is very close to the limit of what can be repaired.
2. Loosen the spokes in the area of the damage to reduce the tension. Typically you will need to loosen at least the three closest spokes. You may have to go up to five; however, if the effected area covers more than five spokes, you should consider replacing the rim. Be sure to loosen each spoke slowly no more than a quarter turn before moving to the next spoke.
3. Using a hydraulic press, align the rim so you can press on the area that is damaged. Support the opposite side of the rim with something like a piece of wood to minimize scratches. This dent was large enough that I would not attempt the repair without a press. A smaller dent you might be able to repair in a heavy-duty vise, but it’s going to be hard. Be careful when using a vise, as it will be much harder to control the wheel, and you don’t want to scratch or damage the rim. It would certainly be helpful to have a friend help you hold the wheel if you work with a vise.
4. You can heat the rim with a propane torch a little in the area you are trying to bend. They are available at most hardware stores starting at $20. This will help the rim return to its original shape and help prevent cracking. Be careful not to heat the rim too much. Do not point the torch toward the spokes, as you could easily damage them. This is also a step that will require reasonable judgment. If you find yourself heating it too much or it requires too much heat, you should consider replacing the rim.
5. Begin to apply pressure to the damaged area slowly. As you apply more pressure you can continue to apply some heat. Go slowly—this is very stressful on the rim and there is no need to rush. Lift the press and check to see how much farther you need to go. You will most likely need to repeat this several times.
6, 7, 8. Once you are getting close to where you feel the rim is straight, you can add a small piece of flat steel to help make a larger flat area, still heating the area you are trying to repair. At some points you might have to push down fairly hard on the other end of the wheel to counteract the force from the press.
9, 10, 11. As you can see, we were able to get this rim back into fairly good condition. You will still most likely have a small flat spot that is manageable. Flat spots are pretty much impossible to remove. You can now true the wheel either on a wheel stand or installing it on your motorcycle and using an indicator that you can attach to the motorcycle. A little duct tape and marker/pencil/straw—just about anything that won’t scratch your rim will work fine. Keep in mind the rim will never be as good as new, as the bending and heating will weaken the rim a little in that area.