Mountain Bike
The Mountain bike is a novelty vehicle in GTA San Andreas. These bikes are the hardest to find on the game, as they don't spawn in as many places as the other bikes, and are rarely seen with pedestrians. This bike is used in Mount Chiliad challenges 1-3. It is faster than any of the other bikes on the game, but is not suitable for tricks or stunts - which will result in the player falling off most of the times. Overall it is a good bike to ride when speed is an element, but stunting is not required.
These bikes also have a glitch, that when backing up with Square (on the PS2), and tapping X (once again, on the PS2), CJ will stretch out of proportion.