As a bicycle repairman I often get asked by friends and neighbors to fix their bikes. One common problem is the straightening of wheels. The techniques you are about to learn are for fixing the wheels from what I call department store bikes, and are not necessarily the top quality bikes you get from an independent bike shop. These tricks are for helping out your neighborhood kids and your local homeless person who, unlike serious cyclists, usually cannot afford new wheels. Most likely they could buy a new bike for the same or less cost than repairing the wheel at a bike shop, but to help out until they become better bikers, or have more money, you can fix their wheel for them.
The wheels get bent usually by people doing things they don’t know any better to do, or doing things they shouldn’t. Like hitting speed bumps at full speed, or riding over a street drain, crashing into a pole, or trying to jump a curb. Sometimes it is from trying to do tricks with their bike that it wasn’t designed to do, like ramp jumping. The common term around here is “taco”; to have tacoed your wheel is to have bent it so that your bicycle can no longer be ridden.
First things first, the tools you will need. You will need a rubber hammer, a regular hammer, a block of wood, your regular tools of course, and your grill or trash can. You will learn about each as we progress through the lesson.
Find out how the wheel was bent. If it is bent from impact then it is a bit easier to straighten than a wheel bent by leverage. Impact bending comes from hitting something or landing after a big jump and so forth. Leverage is from things like the wheel slipping between the grates of a storm drain, causing the rider to stop suddenly and fall over, bending the wheel as a result. You can usually see for yourself how it was bent. If the wheel is out of round and/or uneven it is usually because of an impact accident. If the wheel has bent spokes, it is most likely because of a leverage style accident. Do not be afraid to say no, if the wheel is too badly destroyed and it would cost more than your time to fix it, then let them know their wheel is trashed. If there are broken spokes and you do not have any spares I highly recommend that you tell them they need a new wheel. If they cannot afford it, hire them to clean your yard or something and buy them either a wheel or a new bike. (Most department stores usually have a clearance bike or two on their shelves) You can always tell them that you can try but make no promises. One thing to avoid is giving the impression that you can fix it and it will be like new. Also be wary of those “tempered” individuals that will try to make you buy them a new wheel because your fixing wasn’t good enough. Remind them you are doing them a favor, if what they want is perfection, they can take it to a bike shop.
If the wheel is bent from impact you will fix it with impact. Remove the wheel from the bike. Before taking it off mark the adjustment on the brakes. Use a piece of electric tape on the cable just before you loosen it, or a colored magic marker, something to show you where the cable was before you took off the wheel. Go around it and make sure all the spokes are tight. Not so tight they break but tight enough so no threads show. Remove the tire and tube. Set the tire on top of your trash can so the rim lies on top of the edge of the trash can, if your trashcan is too large, try your grill. I have one of those round charcoal grills that works out just perfect. I used to use my trash can until one day while trying to straighten a twenty inch tire the mouth of the trash can was too big. So I took the screen off the grill and the wheel lay in there just fine. Although grills were not designed to be bicycle repair platforms, if yours is not too rusty it should work fine.
The next step is to take the block of wood and place it over the center. I use an old piece of 4 by 4 about six inches long with a hole drilled in one end so it fits over the axial. Start with the wheel laying high side up and smack the block of wood with your hammer. A few good smacks usually bends the rim of the wheel back to close enough. Be a bit careful here as the wheel acts like it is spring loaded, and that it will bounce. A hard smack can result in a hefty bounce, which if you are not aware of the result, could come back and slap you in the face.
If the wheel was bent due to leverage, it is a bit more difficult to repair, once you have the tire off, give it a close exam. If there are broken spokes or cracks in the metal, it is not reparable. As long as there is no bend greater than 45 degrees you can fix it. To un-bend this kind of damage you will first have to apply reverse leverage. Lay the wheel so that the bend is resting on your block of wood. Using your body weight apply pressure to the two sides of the rim on either side of the bend. Push slowly or it may over un-bend and then break. You will note there are two bends in the wheel. One will be bigger than the other will, so un-bend the bigger of the two first. Gently un-bend each side, as you go make sure any bent spokes are also straightening. Spokes easily respond to your finger pressure so gently un-bend them, by pulling up gently on them. You may have to unbend one half way then un-bend the other side half way and alternate this way until you have it un-bent to close enough.
Once you have the wheel close enough mount it back on the bike. Retighten the brakes where they were before. Do not install the tire and tube yet. If you have a spoke tool that is best, if not then a small crescent wrench will do. Spin the wheel slowly and see where it is rubbing on the brakes. Where it touches the brake loosen that spoke a quarter of a turn. If the rim sticks on the brakes too firmly, then note that spot and give it a smack with your rubber mallet. This is called smack and loosen, a backyard technical term… If the wheel rubs on the frame either you need to unbend the wheel some more or straighten the frame. We can talk about frames in another article.
Make a mark on the rim so you know when you have made a complete revolution. You may need to make more than one. Continue the smack and loosen until the wheel turns without rubbing on the brakes. Remember you are not truing the wheel just straightening it so it can be ridden again. Truing wheels takes patience and the right tools; this is backyard bicycle repair and should not be expected to be perfect. If it were, then you would be working in a bike shop and getting paid to boot.
Once you have the wheel where it makes a full rotation without rubbing anywhere, check the rim for loose spoke nuts and metal burs. You don’t want to poke holes in the inner tube as that causes yet another problem. To tighten a spoke nut, a small straight screwdriver works fine. If you find a metal burr you may need to use a file or medium grit sandpaper to remove it. When you have the inner surface smooth replace the inner tube and tire. Inflate the tire and remount the wheel. Give it a spin to make sure the tire pressure di not re-warp the wheel. If it did a few slow rotations of smack and loosen will move it back to where it will turn freely. Then check it out to make sure the nuts are tight and the brakes work. Give the bike back to the person and have them test ride it while you watch. They usually will ride off and be happy that they can ride their bike again.
A few last thoughts before you advertise your new skills. Be aware and remind your customers that the fixed wheel is not going to perform like new and will be easily damaged again. Tell them to be careful and not to expect to win any races. Beings as this is backyard bike repair I must mention to always keep safety in mind, if you do not have any common sense or mechanical aptitude these skills may not be in your best interest. Do not do anything that will cause injury to yourself or others, also don’t go trying to repair tires on the side of busy streets or in other less than safe areas. You can move to a safer environment, bikes are not that heavy. Needless to say, but I will say it anyway, if the person who wants their bike fixed is injured have them get medical attention first, the bike will wait.