Unveiled at the Tokyo Motor Show, Honda's Riding Assist-e is an all-electric concept motorbike that constantly assesses its position and moves the steering bar to ensure the heavy machine stays upright.

For years, international bike manufacturers have experimented with various forms of gyroscopes to stop motorcycles falling over, said Hiroyuki Nakata, the engineer behind the idea.

"But if you wanted to keep something as heavy as a motorcycle standing, you need a large and heavy gyroscopic device and you need to keep turning it," he told AFP.

Honda's device, however, is only the size of a lamp and can be rigged above the front wheel.