Vuoristorata, a side friction roller coaster

A side friction roller coaster is a type of roller coaster that usually consists of a wooden track and a distinctive lack of upstop wheels on its cars. The cars sit on top of the track and are held to the track with the friction created by the side-friction wheels.

These are one of the oldest types of roller coasters in the world, pre-dating more modern wooden roller coasters. An example of one of this type of ride is Leap the Dips at Lakemont Park, which is the oldest operating roller coaster in the world.