Wikipedia defines it as:
“Cycle ball, also known as “radball” (from German), is a sport similar to football played on bicycles. The two people on each team ride a fixed gear bicycle with no brakes or freewheel. The ball is controlled by the bike and the head, except when defending the goal.”
http://en.wikipedia.org/wiki/Cycle_ball
The description does the actual reality of Cycleball no justice whatsoever.