How To Straighten Bent Bicycle Rim And True the Wheel

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Bending anything on a bicycle weakens it and could cause the part to break while someone is riding the bicycle causing injury or death. Some of the instructions in this article may not be clear enough for anyone to follow as I intended.  Therefore, if you try to follow the instructions below, you do so at your own risk.  These instructions are just to give you a general idea of how some people do things and if you try to follow my instructions you could do something that I did not intend for you to do and it could cause injury or death.
Aluminum alloy rims are much more difficult to straighten than steel rims.  Also, the metal is more brittle and will crack or break easier than steel rims when you are bending it.  After you bend an aluminum alloy rim, check it for cracks and do not use the rim on a bicycle if it has any cracks in it. 

Straightening a bent rim:

I have straightened hundreds of bent rims using these methods, so I know that the methods work well.  Anyone can do it, but the more you do it the better job you will do. 

If the rim is bent sideways like when something hits it from the side, and the bend is a fairly long bend ( a foot or more), you can easily straighten it like this:  Get a limb from a tree or a piece of wood that is about 3 feet long and 7 inches in diameter.  Place the limb on the ground.  Place the wheel on top of the limb so that the two places where the rim is bent the most touches the limb (place each end of the bend on the limb).  Place your foot on the part of the wheel that is on the ground to hold it on the ground while you use your other foot to press the bent part of the rim down until you bend it almost straight.  You may have to do this several times to get the rim as straight as you can.   Sometimes you will bend it too much and you will have to turn the wheel over and bend it the other way. 

If the rim has a short bend, you will need to do it like this:  Get 2 pieces of wood or 2 limbs and place them about 4 inches apart, or the length of the bend.  Place one end of the bend on one of the limbs and the other end of the bend on the other limb with the convex part of the bend on top.  Place the end of a board at the center of the bend and hit the other end of the board with a heavy hammer or a heavy piece of wood.  The board should not be placed on the lip of the rim because it would cause the lip to bend inward.  Place the board so that it will not bend the lip of the rim inward when you hit it.  Before you hit the board, place your foot on the wheel to prevent the wheel from flying up when you hit it. 

Another way to straighten a short bend in a rim is to place the middle of the bend on the end of the round limb with the convex part of the bend touching the limb.  Then press down on each side of the bend.  Use 2 flat boards to press down on the rim to avoid bending it at the place where you are putting pressure on it.

 If a rim is warped because it has a broken spoke or because a spoke or spokes are looser on one side than the other side  in that bent place, you may not need to bend the rim to straighten it as described above because the rim may not be bent, or may not be bent much, and you can get it back true just by tightening a few spokes.  But, sometimes when something hits a spoke hard enough to break the spoke, it also causes the rim to bend and you will need to bend it back as described above.  

If the rim is not actually bent, or if it is bent only a little, just tighten 3 or 4 spokes (or all the spokes along the bend, plus a little tightening of spokes just past the ends of the bend).  You will need to make more turns of the spoke nipples on the spokes that are nearer the center of the warped place.  

When you get through tightening spokes, all of the spokes in the wheel, ideally, should be the same tightness; but, sometimes if the rim is bent a little, in order to get the wheel true, you have to leave 3 or 4 spokes on one side a little tighter that the spokes on the other side.    If the warp was caused by some spokes being too loose and the rim was not bent, then all of the spokes should be the same tightness when you finish.  

When you do the final fine truing, when you find a spot that is not true enough, pull on all of the spokes around that spot to see if some spokes are tighter on one side than on the other side.  If you find that some spokes on one side are too tight, you may be able to loosen those spokes in order to get that spot true instead of tightening spokes on the other side.  If you have to tighten spokes much tighter on one side than the other side at a warped place in the rim, you need to straighten the rim by bending it as described above before trying to true it by tightening spokes. 

Don't turn a spoke nipple much with the tire aired up because the nipple could drill a hole in the tube  as you turn the nipple. 

If the sides of the rim are bent inward making the rim narrower, use a large adjustable wrench to fit over the edge of the rim and bend it out. 

If the rim has a flat place like it ran into a tree, you can bend it back like this:  Take the nipples off the spokes in the flat place and take about 4 nipples off  past each end of the flat place.  Get 2 limbs and place them on the ground so that the  limbs are the same distance apart as the length of the bend.  Stand the wheel on these 2 limbs so that one end of the bent places touches one limb and the other end of the bent place touches the other limb.  Hit the inside of the rim with something round and heavy made of wood.  Or, you could put a piece of steel that is rounded about the same as the rim, pad the steel with an old inner tube, place the steel at the center of the bend, place a board on the steel, and hit the board hard with a heavy piece of wood.  This will bend the flat place back round again.  Check to see if it is the same distance from the hub as the rest of the rim.  If it is, put the nipples back on the spokes and tighten the spokes. 

If the rim is not round enough and is not  bent, you can get it round by loosening some spokes and tightening some spokes.  If all of the spokes are tight, you will need to loosen some spokes around the spots that are too close to the hub, then tighten the spokes around the places where the rim is too far from the hub.  The spoke at the center of each low spot will need to be loosened more that the spokes on each side of it.  The spoke at the center of each high spot will need to be tightened more that the spokes on each side of it.

If the sides of the rim are bent out, lay the side that is not bent on a flat piece of wood and hit the part that is bent with a hammer.

When all of the spokes in the wheel need to be tightened, do not tighten them all the way the first time around.   If you tighten the first spokes as much as you can, it will pull the hub away from the center of the wheel.  Partly tighten all of the spokes the first time around with the same number of turns of each  nipple.  After you partly tighten all of the spokes the first time around, they all should be a little loose after you finish.  Next, go back and tighten all of the spokes again with  the same number of turns of each nipple.  After you go around about 3 times, most of the spokes should be as tight as you want them to be.  A few of the spokes may be much looser than the other spokes, and you can tighten them if the rim is round.  Check the rim for roundness by seeing if the brake shoe hits the center of the side of the rim everywhere when the wheel is turned; or, you can see if the rim is the same distance from the hub everywhere. 

If the rim is not round, you may correct the HIGH SPOTS if ALL of the spokes are still a little loose.  If all of the spokes are tight, you should first correct the low spots by loosening about 6 spokes at the place where the rim has a low spot, loosening spokes more at the center of the low spot and less on each side of the center.  To correct high spots, places that are too far from the hub, Tighten spokes at the high spot. 


After you finish tightening the spokes, some of the spokes may be sticking up out or the nipple and you will need to file them off or they will punch a hole in your tube. 

You can see videos on youtube showing how to straighten bent rims.  My guide on  Google's blogger.com website shows how to see the videos I selected by other people.  Look under "WHEEL"  in that guide.
   
How to install Bicycle Parts, all kinds. See videos on youtube

DISCLAIMER 

I am not responsible if anyone is injured because they followed the instructions in any of the articles I wrote, or in any video or article by others that I recommend.  Some information in the articles that I wrote and in the videos and articles by others that I recommend could be dangerous, and anyone who tries to follow the instructions in those articles and videos could be seriously injured.  Repairing or servicing bicycles can be dangerous.