Steel, ball-bearing wheels that allow sections to roll freely along door tracks.

wheels on the sides of the door that run in the Tracks.

a stationary training device that allows you to train on your bike indoors.

an indoor training device consisting of three long cylinders connected by belts. Both bike wheels roll on these cylinders so that balancing is much like actual riding.

Relatively small-diameter cylinders, or wide-faced sheaves, that serve as support for ropes.

Relatively small diameter cylinders which are free to turn while supporting ropes Strand - An arrangement of wires helically laid about an axis. or another wire or fiber center to produce a symmetrical section

A device with three or four cylinders in a frame. You can balance a bicycle on them and ride indoors to maintain fitness and work on pedal stroke.

The rollers are the wheel part of the roller assembly that roll freely using ball-bearings.