What is that thing called?

[daveymark]

You put your bike on it so you can excersice indoors, you just rest the back wheel on it so it can spin in the air.

What is it?

 

[wedi42]

bicycle trainer
edit
like this?

 

[speg]

A brick?

 

[Analog]

a jack stand?

 

[MercenaryForHire]

Originally posted by: speg
A brick?

No, that's what you throw at bicycles.

- M4H