Deadly Prospect by Fleur Beale

Lincoln MacKenzie doesn't expect to get into motorbikes, but when his uncle takes him for a ride, he's hooked. He's never done anything so exciting in his life. Trouble comes quickly though. His father is seriously injured in an accident and while his parents are away, Linc's 13 year old brother gets involved in a local gang. Linc is caught between wanting to ride, putting up with his nagging grandmother, thinking is father might die, and trying to keep his brother away from his mates. The story culminates when Linc must face the gang and ride for his life. Really exciting, easily read and especially great if you want to know all about bikes.