How Does a Bicycle's Friction Drive Work?

[twistedmind]

Can anybody help me with these forces, I appreciate the effort.
The roller shown sitting on top of the circle which is the bictcle tire is spinning counterclockwise imparting a tangential force on the bicycle wheel.
Is the roller creating the force to drive the wheel forward, or is the entire assembly moving the bicycle forward?
whas that question too long?
thanks

 

[rcgldr]

Assuming that the roller, assembly, and bicycle tire are all connected as a unit, the roller is applying an "internal" (within the bicycle system) force to cause the tire to rotate. At the contact patch between tire and pavement, the tire exerts a backwards force onto the pavement, coexistant with pavement exerting a forwards force onto the tire.

It's the pavement's forward force that propels the motorized bicycle forwards.