Thieves are targeting homes where cars mounted with cycle racks are parked outside, a senior Lancaster policeman has warned.
Sergeant Guy Hamlett urged city residents to ramp up security where it may be obvious to criminals that they have valuable possessions.
Lancashire Police have declared October Bicycle Awareness Month after thefts rocketed during the summer’s heatwave.
The general trend in the number of bike thefts is, however, downwards, Sgt Hamlett said.
He told the Guardian: “We are seeing an increase in sheds and garages being broken into.
“What we think is happening is thieves are seeing almost signposts outside people’s houses, such as cycle racks on the roof or people with vehicles which have writing on the side about cycling clubs.
“We really want to get the message out for people to stop signposting their valuable property.”
Bikes in the £500 to £2,000 bracket appear to be the ones being most-commonly stolen, Sgt Hamlett said.
He went on: “The key crime prevention message is please remove your bike racks and store them out of sight when not in use. Use a strong lock on sheds, garages and outbuildings.
“If possible, make sure your shed door doesn’t have exterior hinges which criminals can attack as a way of gaining entry.”