Ending a year of speculation, inventor Dean Kamen yesterday unveiled the product formerly famed as Ginger, and now known as the Segway Personal Transportation Device.

Apple CEO Steve Jobs, who saw the device last year, suggested the product will "transform the way cities are built".

However, Trevor Baylis OBE – UK inventor of the clockwork radio – remains "sceptical" about Segway.

"I saw devices like these in the 1960s," Baylis told Macworld. "Ginger is not a million miles from the Sinclair C5, and we already have electric scooters."

Segway is a two-wheeled personal-transportation system that is "driven" by body movement. It does so through its use of a technology called Dynamic Stabilization.

Dynamic Stabilization simulates the way the human body moves, so that Segway will move forward when its rider leans forward and reverse when its rider leans back, the company said. This is achieved by having gyroscopes and tilt-sensors that monitor the rider's centre of gravity around 100 times per second, the company said. The devices contain ten microprocessors.

Sidecar sweep Baylis warned: "The trouble with gyroscopic controls is that they can develop a mind of their own. It's like a motorbike and sidecar; when turning corners, the sidecar begins to pull one way, while you struggle with the bike to turn in the other direction. It's gyroscopy that keeps a bike on the road."

He conceded that what he had seen of Ginger's controls so far had seemed very "elegant", but added: "What happens if you bump into someone or something? What do the gyroscopic controls do then?"

"I like absolute controls", said Baylis, "not controls which give the vehicle a mind of its own".

Three models of Segway be available initially: the i-series, the e-series and the p-series. The i-series will be designed for range and speed across different terrains; the e-series will be used in business applications and will be able to haul up to 75 pounds beyond the rider's body weight; and the p-series will be targeted at densely populated areas. Degway is expected to ship in late 2002 and will cost $3,000.

Other features include a maximum speed of 17km/h and very low fuel consumption - the device will travel 17km for a full electrical charge. Charging up the device costs around five pence.

Baylis concluded: "With Segway the biggest invention involved the media hype."