The Carrera Vulcan bike was left behind in Bomber Wood at the rear of Kingfisher Close, Hartlepool, after police officers were alerted to the fires being lit.
As the youngsters “made off”, the bike, which has distinctive green and yellow markings, was left behind.
The incident took place on Sunday April 3.
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Anyone with information is asked to contact PCSO Fowler or PCSO Duffield of the Hartlepool Neighbourhood Police Team on the 101 number.
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Police officers are appealing for help to track down the owner of a discarded mountain bike
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