A new generation of electric bicycles able to do 80km/h are likely to result in serious injuries, according to a road safety expert.
The bikes, being released in Australia, look like normal pedal-powered bicycles but have the assistance of a battery-powered motor on either the front or rear hub, or through the crankshaft.
Professor Don Aitkin, who chaired the NRMA/ACT Road Safety Trust, said, if an e-bike hit a pedestrian at 80km/h, it could inflict serious injury.
In Australia, the bikes do not need to be registered, or their riders licensed, because regulations are supposed to cap their speed at 25km/h.
Some commuters were using bikes designed for off-road use, or heavily modifying their own cycles - and there was little current laws could do about it.
The internet was full of examples of e-bikes being ridden fast and dangerously in heavy traffic on Australian streets, the ABC reported.
Videos featured electric bikes capable of producing 1000 watts or more, designed for off-road use, being used to keep up with cars on the open road.
Canberra retailer Simone Annis said some riders were making dangerous modifications using imported components to create their own 'Frankenstein' electric bikes.
"We see people all the time with bikes which are just hideous bikes, with not very nice kits on them, which they've bought over the internet.
"Obviously we wouldn't encourage that, and it could be highly dangerous riding a really, really fast bike with brakes that don't work properly and so forth," she said.