Zeta II

This article was published in 1997, in Newsletter 14.

The Zeta II (Zero Emission Transport Accessory) is Sir Clive Sinclair’s latest gadget aimed at providing the British public with electrically powered transportation. It consists of a lead-acid battery strapped under the bike’s crossbar, a motor with a belt held above the front wheel by two metal poles, a couple of brackets, and a piece of string with a lever.

The idea is that you engage the Zeta II once you have built up some momentum by pedalling, and the motor then whizzes you along at about 10 miles per hour. A switch on the handlebar allows you to turn the motor on and off, and a lever with a bit of string drops the motor onto the wheel. Sinclair claims that you can get a range of 5 miles out of the device, or up to 14 miles if you pedal as well. The battery comes with a charger which takes 14 hours to recharge, consuming about a penny’s worth of electricity.

Photo of Zeta II (40k)

When the device arrived it was missing the installation instructions, battery leads, and axle brackets. It took two phone calls to the help line to reach an operator who understood the problem. I was promised that the relevant parts would be despatched immediately. Three days later the rest of the kit arrived in the post.

I first tried to fit the unit to my partner’s 1969 BSA town bike, and failed. The metric threaded bolt required to fit the Zeta II to the forks did not fit the Whitworth thread of the front brakes. I could therefore either have a Zeta II or front brakes, and the brakes won. In the instructions Sinclair recommends that you buy a new brake with a metric thread.

I then tried to fit the unit to my new Trek hybrid bike, and almost succeeded. After removing the front reflector I could slot the relevant bolt through and clamp the unit to the front. It didn’t even tangle with the brake or gear cables. However, then I discovered that the front support stanchions for the device did not reach the axle, and so I could not fix the motor unit safely to the bike.

I finally got round to buying new brakes for the BSA and successfully installed the device. Here are my observations:

  • 8-10 mph, the speed at which the Zeta II propels you, is very slow.
  • The electric motor whines loudly enough to turn heads as you pass by.
  • The ‘assistance’ you get from the device is almost undetectable.

If you don’t pedal, any slight head wind or incline causes the motor to go into overdrive, and the temperature cut-out mechanism switches the motor off within minutes. You then have to wait about 10 minutes before it starts working again.

In conclusion, although the idea behind the Zeta II may be fine, something is lacking in the execution. You need to be very mechanically minded to fit it, and even then you are likely to run into many troubles. Once you get it working, the propulsion you receive is minimal. Finally, Sinclair’s manufacturing and quality control processes could do with some improvement. In my opinion the Zeta II is only suitable for extremely interested hobbyists with far too much spare cash.

If you still want a Zeta II you can order one at a cost of £95 plus £5 postage and packing by phoning (01993) 279300.

Keir Finlow-Bates