Hamilton police say they are following strong leads after a man was stabbed in the neck and had his ear bitten in half when he chased suspected thieves.

The 32-year-old man suffered wounds to his neck, arms, head and torso, including an ear being bitten in half, when he disturbed two men allegedly trying to steal his bicycle and chased and struggled them.

Detective Sergeant Ricky Thompson said the investigation team had been able to interview several witnesses who had come forward following the attack on MacFarlane St early this morning.

"Several people have told us they heard the disturbance on the street and looked out to see what was going on, from their statement we've been able to piece together a sequence of events and are now following strong leads in relation to who was responsible."

The man's ear was severed but remained attached. He had left hospital and been interviewed by detectives.

Mr Thompson said the attack would have been very noisy and anyone with information should contact police immediately.

One attacker was described as a Caucasian of medium build, about 180cm tall, with a "Justin Bieber-style haircut".

He was wearing jeans and a dark hooded sweatshirt and may have had a black BMX bicycle with white handle bars.

No description was provider of the second attacker.