Riding the vogue for eco-conscious products, companies ranging from battery to tire to motorcycle makers in Japan are looking to cultivate a market that beats even hybrid cars in green credentials: electric bicycles.

Japan's motor-assisted bicycles use a small electric motor and battery pack mounted inconspicuously on the bicycle to propel the rider, constantly adjusting the motor's force to the speed and resistance of the pedalling.

That makes cycling up a hill or while carrying a heavy load a cinch, winning over a growing number of elderly and housewives in Japan. Sales of electric bicycles more than doubled from 2000 to 315,000 last year, as they became more affordable and practical.

"Once you've ridden one of our motor-assisted bicycles, you'll never go back!" a spokesman at Yamaha Motor beamed, urging reporters to try out a few of Yamaha's 17 electric bicycle models during a test-ride.

The motor switches off automatically once the speed reaches the 24 km/hour legal limit for assisted riding, classifying the vehicles as bicycles, unlike the popular electric bicycles sold in China, which would require a licence in Japan. Yamaha Motor, Japan's No.2 motorcycle brand and top maker of electric bicycles, expects more of a tailwind for the market.

Thanks to advances in rechargable batteries, Yamaha's standard electric bikes have a range of 39 kilometres, or 67 kilometres using an optional mode that activates the motor only when desired. That's about double the range of its first model introduced in 1993.

Charging time has shrunk to two hours from 10, with one charge costing around 10 cents. One catch though is that batteries need to be replaced roughly once every two years, and they cost at least €176 each.