Riders are being warned to be on their guard after bike trails in Derbyshire were sabotaged with potentially-lethal traps.
It comes after routes were targeted by yobs who have placed branches at head height and left rocky obstacles and tyre-piercing pins on bike trails.
The cycling community in Derbyshire is becoming increasingly concerned by the growing trend and fear it is only a matter of time before someone is seriously injured or even killed.
In recent weeks thick branches have been cut down and fixed at head height along a bridleway in Bradwell, carpet tacks have been laid across a road in Bamford and a wall of rocks have been constructed across a path in Aston in the Peak District.
A number of pictures have also been circulating on internet forums showing how riders have been forced to pick up dozens of pins from roads in the Peaks. In addition, there have been reports of similar sabotage incidents in west Sheffield, Doncaster and along the Trans Pennine Trail.
A police spokesperson said officers are aware of “trail sabotaging and take all reports of this nature very seriously.”
Fulwood man Chris Maloney, who writes the Keeper of the Peak blog that promotes cycling, said these attacks are putting people's lives at risk.
The 37-year-old father-of-two said: “These are just idiots with a vendetta. The traps are designed to stop people cycling and enjoying the outdoors.
“If someone sees these obstacles late and comes off their bike then this could cause very serious injuries or even put people's lives at risk. It needs to stop.”
Dexter Johnstone, secretary of campaign group Cycle Sheffield, also condemned the vigilante actions.
He said: "The people doing it are complete idiots. It is incredibly dangerous and there have been stories in the national media about people being seriously injured as a result.
“It is illegal and the people doing so should be arrested and prosecuted."
Mr Maloney said he does not really know why someone would do such a thing.
He accepted that, like within any group, there will be a small section of cyclists who on occasion go too fast.
But added: “Whatever people's gripes are there is absolutely no justification for putting people's safety at risk.
“We have a mantra in the cycling community of being respectful and thinking about other people enjoying the outdoors.”
Mr Maloney described how huge efforts have been made in recent years to encourage more cooperation between walkers, runners, cyclists and horse riders.
This includes regular meetings to discuss ways of improving things such as access to routes.
But he said vigilante actions go completely against this joined-up approach and is “not in the spirit of the great outdoors.”
He added: “If the people sabotaging the trials have an issue then I would like to invite them to one of our meetings to discuss this, rather than setting traps that can hurt people.
“We need to find a way so that we all get along.”
In a statement, police said: “Our officers are aware of reports of alleged trail sabotaging and take all reports of this nature very seriously.
“Trail sabotaging has the potential to cause serious injury, and we would encourage anyone who comes across evidence of this, or any suggestion of this taking place, to report it to the police via 101.”