A thief was forced to leave behind the £8,000 bike he took from the Giant store in Cambridge as it didn't have any pedals attached to it.
According to the Cambridge News, shop staff and members of the public chased the man as he fled the store along Hills Road last Thursday.
Regular customer Jennifer Green was locking her bike up nearby when she saw the man make off with the Giant Defy SL and took off after him.
"It was a split second thing. I heard a shout and looked round, and saw a man running down the road chasing a man running with a bike," she told the paper.
"I didn't have time to process it, I just thought 'oh bloody cheek to grab someone's bike', and went after him.
"If he had been cycling away I would have been much slower on the uptake, but he had made a poor choice taking one without pedals."
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The thief reportedly threw the bike to the ground when he realised he wouldn't be able to escape the chase and made off in a black Audi.
Police describe the man as white, 6'1" athletic build with short light hair, between 20 to 30 years old, wearing black trousers, red/orange Nike shoes with orange laces, and a grey fleece with a black Ferrari jacket underneath.
Anyone with information is asked to contact police on 101, or call Crimestoppers anonymously on 0800 555111.