Staff running a cycling speedway club in Sheffield are devastated after raiders broke into their premises and made off with a fleet of bikes.
A container belonging to Sheffield Cycle Speedway Club was broken into between Thursday evening and Friday morning at their track at Graves Health and Sports Centre, in Norton.
More than a dozen customised bikes - worth up to £250 each - were stolen.
The club's vice-chairman Robert Mawhood is now appealing for anyone with information to come forward.
He said the bikes are unsuitable for roads and pavements and should only be used on a cycle speedway track.
Mr Mawhood said: "The container seems to have been cut by an angle grinder. A generator was stolen and we're not sure if the same people stole the bikes or they left the container doors open and others took the bikes.
"The bikes aren't usable for anywhere else. They have specialised handle bars, no brakes, a single freewheel cog setting, no lights and no gears.
"They are all set up for racing on a cycle speedway track.
"I am devastated about the theft. Some people just don't seem to appreciate what people have put in to help out the community and youngsters and then that needs replacing."
Mr Mawhood said the bikes have been donated from former racers or bought from a specialist company in Birmingham. Some of the smaller ones have been customised from donated BMX bikes.
Four of the bikes and a frame have been returned, while youths have been seen riding on others in Lowedges, Jordanthorpe and Greenhill.
Mr Mawhood said: "Fortunately we have a stock of bikes at our other track at Cookson Park, so we'll have to use them until such time that we get the bikes back.
"This isn't ideal as we'll have to keep transporting the bikes backwards and forwards."
The club has produced the Women's World Cycle Speedway champion Vicky Brown and its under 18s are national team champions.
A South Yorkshire Police spokesman said: "Police are investigating the reported theft of pedal cycles from a business premises in Sheffield last week.
"Enquiries are ongoing and anyone with information is asked to call 101 or email firstname.lastname@example.org quoting crime number K/94553/2017."