Police in Bedforshire are looking for a gang of about 20 mainly Asian youths between the ages of 15 and 20.
The boy was attacked while cycling next to a river in Bedford on Thursday night.
He was punched and kicked before the gang threw his bike into the water.
Nose broken
The boy's nose was broken in the attack. He also suffered black eyes and cuts and bruises.
The gang stopped the boy as he cycled along the river in Queens Park, near the Prebend Street Bridge.
When he told them he was not from Queens Park, they punched and kicked him in the head and body until he fell to the floor and threw his bike into the river.
The boy was treated in Bedford South Wing Hospital for his injuries.
Police said all the attackers were Asian, other than one who was a mixed race black youth.
Their victim described three of the group. One was mixed race, 15 years old with short Afro hair, wearing a light blue baseball cap and grey hooded top with dark blue jeans.
Gelled hair
The second was Asian, 5ft 11in tall, 20 years old, with skinhead hair and a thin pencil-style goatee beard. He wore a red baseball style T-shirt and black Adidas track suit bottoms with three white stripes.
The third was Asian, around 20, 5ft 11ins tall with with short gelled hair which was pushed forward.
PC Darren Wright is treating the attack, which happened at 1840BST, as a racially-motivated assault.