James FitzGerald, owner of Justebikes, warns that electric bikes modified so they can go faster than the legal limit of 15.5mph have not been tested above that speed

Retailers are selling powerful electric bicycles with motors capable of breaking the regulations limiting their speed.

Commuters have been filmed zipping along busy roads in London on battery-powered bikes that appear to be travelling faster than legal limits.

So-called ebikes have an electric motor that is used to assist the rider’s pedal power. Traffic laws state the motor must cut out at 15.5mph and must have a maximum power of 250 watts.

Powerful electric bikes clocked at up to 28mph

Ebikes with bigger motors and capable of faster speeds are classified as mopeds and must be registered with the Driver and Vehicle Licensing Agency (DVLA), taxed and insured.

In February a cyclist who posts YouTube videos under the name “CycleGaz”, posted one of himself being overtaken by an ebike in central London. CycleGaz