Planet Sinclair


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O 1997

Last updated
26 Feb 1998

Look, no feet!

THE GUARDIAN - 16 July 1997


Yesterday in London, Sir Clive Sinclair launched what he describes as a substantially improved version of his battery-powered bicycle propulsion system, Zeta - zero emission transport accessory. At 100 (including VAT, postage and packing), Zeta II is two-thirds the price of its predecessor; it comes in two parts, a driving unit and a battery pack; it drives the front wheel rather than the rear; and it has a more efficient motor, writes John Stansell.

Zeta II can power a typical cycle on a flat road at 12mph for five miles, or up to 15 miles if the cyclist pedals as well as using the power assistance. The system can be used on public roads legally by anyone over 14 without needing tax, insurance or a driving licence. But the noise could be a drawback - it sounds like an angry hair dryer.

The original Zeta - whose battery was mounted in the same box as the motor and control electronics - was attached by a clip to the rear forks, just above the back wheel. This caused problems on some cycles, when the clips slipped, twisting the unit and sometimes derailing the drive belt. Sinclair claims the new system - which fits to the bolt through the front forks holding the brake callipers - cannot twist and the belt cannot be derailed.

The drive unit - which, like Zeta I, uses a flexible rubber belt that moulds itself to the shape of the wheel has been modified so that the greater the power required, the higher the downforce on the tyre, which he claims prevents slip.

Sinclair also says that the separation of the battery unit and motor has cut the overall weight, because it allowed the design team - led by Alex Kalogroulis - to use plastic mouldings rather than aluminium alloy. The 12V battery is a standard lead acid type which can be discharged and recharged 500 times at a typical recharging cost of 1p and a battery life of about five years.

Sinclair investigated other types of cell - notably nickel cadmium - but the added cost and recharging problems of Ni-Cad cells convinced him that lead acid was still the best solution.

People wanting longer range can buy a spare battery for 30 or install a larger one, but Sinclair says that a survey of 100 of the 10,000 Zeta I users in the UK found that only 5 per cent wanted longer range.

Sinclair has long held the view that electric propulsion would meet the transport needs of the millions of people who only make short journeys, and would have a major effect on pollution. He says he would like to develop a lightweight four-wheeled car, but is inhibited by the cost, the lack of a suitable battery design, and perhaps by the legacy of the unfortunate C5 three-wheeler. He is currently developing an ultra-lightweight folding cycle using composites and other advanced materials to get the overall weight below 2kg.