Note: This article covers Imperial Speeder Bikes. You may be looking for the Rebel Speeder Bike.
"Speeder Bikes are very fast and see widespread deployment in ground forces. Because of their light armor, they're an easy target when stationary, making them best suited to anti-infantry operations."
~In-game description of Speeder Bike (Empire)
The 614-AVA is an upgraded version of this, trading health for more speed and damage
An excellent combination of small size (for a vehicle), speed, damage and health, the Speeder Bikes are virtually identical to the Rebellion version but are far more dangerous in Empire hands because of Repair Droids. A group of Empire Speeder Bikes backed up by Repair Droids are only threatened by Rocket Turrets, Y-Wing traps (which everything is vulnerable to) and heavily over-powered donated troops in a Squad Center. Accompanied with a good turret killer like the AT-MP Mark III and careful air strikes aimed at Rocket Turrets in particular, an Empire Speeder Bike squad can be absolutely devastating to an enemy base.
Speeder Bikes are usually asked for when someone needs troops in their Defensive Outpost in a squad war, but that doesn't mean you can't use them in your main base. They are excellent infantry killers, and enjoy the fact Rebels are more infantry-based.