When you have to travel with your bike wheels, wheel bags come in handy. There are three basic types of bicycle wheel bags: hardcover, soft cover, and cardboard. A hardcover wheel container will be molded from plastic or some similar material and will keep shape and form whether you carry your wheels on the airplane or check them through as baggage. As such, hardcover wheel containers are bulkier, heavier, and will often induce higher airline fees to check them in, not to mention that it is highly unlikely that you can carry these wheel compartments onto an airplane itself. Soft cover wheel bags are made from ripstop nylon or similar cloth-like materials and may have some degree of foam or other padding to protect your wheels. But overall, soft cover wheel bags are no more than carrying bags for your wheels, not offering much protection from impacts of any sort. At the very least, they make it easier to carry your wheels from place to place and they do keep grease and dirt from your wheels from rubbing up against your clothes or other bags or other things. Cardboard boxes are often available in a roughly 30" x 30" shape, which will contain 700c or smaller wheels with no problem. These wheel boxes can be used to ship bicycle wheels via US mail, FedEx, UPS, or other services, and are useful for when shipping wheels when you are flying. Wheel boxes can be bought, but you can likely find used wheel boxes at your local bike store just by asking. One thing that bike riders like to do is to put race decals or stickers on wheel bags, to commemorate races or other noteworthy and memorable rides they have competed in order completed.