Sinclair is working on successor to the C5

Eighteen years after he tried to tempt city dwellers to take to the roads in an electric tricycle invisible to lorry drivers, Sir Clive Sinclair announced yesterday that he is again attempting to revolutionise personal transport.

The inventor of the ill-fated C5 confirmed that he is working on a secret successor to the plastic three-wheeler that was condemned as a death-trap by motoring groups when it was launched in 1985.

Sir Clive has produced a prototype of his latest solution to the urban transport crisis, which is being developed with an unnamed company specialising in electric motors. But the man whobrought the nation creations from the ZX Spectrum computer to the world's smallest AM radio refused to discuss the design.

A spokeswoman said: "It is a new product aimed at getting people around town, but we're not saying anything more."

Unlike the C5, which required its owners to risk all by driving on the road, the new vehicle, due to be launched next year, is understood to be designed for use on pavements.

Sir Clive, who was credited with pioneering the home computing revolution by putting millions of ZX Spectrums in teenagers' bedrooms, revealed his project as he road-tested the only similar product on the market, the Segway. The hi-tech scooter, stabilised by gyroscopes, is selling well in the United States, where it is used by postal workers, amusement park staff and even police.

But the originator of its would-be British rival believes he has spotted a gap in the market because the Segway is too heavy at 40kg (88lb) and too fast for crowded European streets.

Sir Clive told BBC News Online: "In London, there are lots of people milling around - a heavy vehicle like that ... and doing 15mph, if you hit someone it would just knock them for six."