When some people get a bent rim, that may spell the end of their bike usage. It doesn’t have to be the end as straightening a rim is not that costly if you take it to a bicycle repair shop. I recently took a bike rim to a repair shop after a few initial attempts to straighten it myself. The repair cost for my rear mountain bike rim was $17.
Alot of multi-tools for bikes come with a small tool for tightening/loosening the spokes on a rim in order to straighten it out. Where the spoke comes out of the hub of the tire there is a nut that is often called the “nipple”. You need the right sized wrench for tightening or loosening the nipple. I purchased a circular Raleigh tool from Canadian Tire with three different sized wrenches to try to straighten my tire. Unfortunately, none of the three nipple wrenches were exactly the right size so I was in danger of stripping the nipple if I kept on trying to fix it myself. That is when I decided to take it to a bicycle repair shop.
Generally the industry standard for bicycle repair tools is a brand called Park Tools. They offer quality nipple wrenches at a reasonable price, often under $15. If you are going to “true” the rim yourself, you might want to bring the rim into the shop and try out the nipple wrenches or ask a service person which one to purchase. Some of the better bike multitools might have the right size nipple wrench for your rims so that is an option as well which would give you some other tools you might want to take with you. The ability to straighten a bent rim when you are in the middle of no where might be a useful skill for a hardcore cyclist.
If you need to get your rim straightened at a bicycle repair shop, you might save yourself a few dollars and make their life easier if you remove the rim from the bike and remove the rubber tire from the rim as well. This makes their job easier.
You can pay alot of money for a rim compared to the cheaper rims you might have on a bike you purchase from Canadian Tire or Walmart. The cheaper rims are often only “single walled” as compared to “double walled” rims. A double walled tire has a second wall on the inside of your tire riding over the spokes which makes it stronger and less likely to puncture your tire. The bikes we offer have some good components on them but they are not the expensive double walled rims that a hardcore cyclist might be willing to pay for. If you take our mountain bikes down the side of a mountain you might be risking catastrophic rim failure. They will take a good beating on some rough terrain but not that type of beating.
Straightening a bike rim is often where the DIYers who might fix most things that go wrong with their bike will decide to take it to a bicycle repair shop. Often it is worth letting people with the proper tools do the job for you if you have a significant bend in your wheel. For a slight bend that causes a brake rub, it might be worth your while seeing if a cheap bike multitool from the dollarstore has the proper nipple wrench on it, checking out some youtube videos on what is involved in straightening a rim, and making the effort yourself to “true” your rim.
Fatbike rims are often strong enough as single walled rims. Adding an inner rim involves a covering a bigger rim surface and often a single walled rim is considered sufficient.
Rims come with more or less metal which can determine how strong they are, even as a single walled rim. Also, rims can be make from different materials than steel such as aluminum and carbon. When you are shopping for an expensive bike these are some of the rim related features you might look at.