A HAVE-A-GO hero who chased down a bike thief has urged cyclists to better protect their bicycles.

The man, who asked not to be named, spotted a thief attempting to break the lock and make off with a bike in Summertown on Sunday.

The bike, potentially worth more than £400, was locked up outside Sainsbury's in Banbury Road about 4.30pm.

The passerby, who was walking past, said: "My girlfriend noticed someone acting suspiciously around the bikes, so we watched him.

"When we realised he was up to no good we shouted and he just looked at us [and shouted rudely back].

"That is when he started to step it up a gear, as I think he was panicked'.

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The onlooker said the thief was using another bicycle seat to snap the lock around the more expensive bike.

He added: "I immediately started to run after him down South Parade, but he was on the bike by that stage"

The have-a-go hero was unable to keep pace with the thief and returned to tell the bicycle's owner the bad news.

It's fourth time he has interrupted bike near Summertown and said it was a huge issue for the city.

He urged cyclists to use both a combination lock and D lock to help protect bicycles from thieves, and to register serial numbers online.

Police have been asked for comment.