The motor cross motorbike and a Renault Clio collided in Sheepridge Road shortly before 6pm on Saturday.
A West Yorkshire Police spokesman today said: "At the time of the collision the Renault was performing a ‘U’ turn by Wigan Lane and the bike was travelling towards Fartown from the direction of Deighton.
"As a result of the collision the male motorcyclist was taken to hospital in a serious condition."
Officers are appealing for anyone who witnessed the collision or saw the motorcross bike prior to the collision are asked to call 101, quoting log 1450 of Saturday 21 May.
Information can also be passed on via the force's live 101 webchat system.