I am buying these rims for a build, you'll need a single speed freewheel sprocket, as most bikes come with cassette style gears. To convert it to single speed, you'll need a chain tensioner and a single speed chain. Single speed chains are stiffer, so they won't flex and run off your gears. Edit: make sure you use proper size rim tape on theses rims so your tubes don't pop. I recommend buying cruiser tires (typically 26x2.125) as I saw in the review that they fit on the rims. That way you don't buy fatter tires that might not be able to clear the frame, as these rims are wider than your typical 26 inch ones.