Zapping along

This article was published in 1999, in Newsletter 25.

Yes, Cambridge Cycling Campaign has gone motorised! There are quite a few varieties of electric bike on the market now, and we’ve tested add-on kits from the German manufacturer Heinzmann and the American ZAP (Zero Air Pollution).


The Heinzmann kit consists of a hub-motor, a battery pack on a specially made carrier, a speed control twist-grip, and of course a charger. The hub motor can be fitted to front or rear wheel, but fitting to the rear wheel restricts the options on gears, and the front seems to be the most popular choice. The quality of the fittings and the electrical connections is very good, and the carrier is neat, with the battery pack sliding into it leaving a normal rack to carry panniers or a bag above.

Riding the Heinzmann can be done without turning the pedals at all, just turn it on, twist the grip, and away you go. Riding in this way the battery will last for 12-15 miles, cruising at a fairly constant speed even up hills. Using the pedals to provide some more power will extend the range, up to about 25 miles, but the speed of travel will stay much the same.

Once up to its governed speed the motor resists any added power through pedalling, and it will even resist gravity pulling down hill. Simply closing the twist-grip control completely disconnects the motor though, and the bike can be pedalled or allowed to freewheel, without any drag from the motor. It worked best simply riding at its natural speed, shutting the motor off on the level or downhill and assisting it gently uphill.


The ZAP kit is rather different. The motor drives a steel wheel which rubs against the tyre, and the battery pack is in a bag with Velcro straps to allow mounting wherever convenient. Control is by pushing a lever to move the drive wheel against the tyre and then holding a spring-loaded switch closed underneath the handlebars. The ZAP does not seem to have a built-in speed control, but relies on the power output being insufficient to propel the bike at more than 15 mph. ZAP’s electrical connections were insubstantial, and looked as if they would not resist water for long.

The battery charger was not as sophisticated as the Heinzmann’s, and took twice as long to recharge. Riding the ZAP-equipped bike took a different technique too; the motor would continue to assist while pedalling faster or going downhill, but was not as capable of maintaining its speed going up hill. The range was shorter, about 10 miles letting the motor do all the work and 15 miles or so giving it some assistance with the pedals. With the motor switched off there is still considerable drag, and the rider has to reach awkwardly behind the down tube to push the lever to bring the drive wheel off the tyre.

Both kits have options on accessories, including lights for the ZAP, and can be supplied as a kit or built into a new bike. The Fold-It with Heinzmann as tested costs £1150, with the motor kit at £700, and the ZAP-equipped ‘ElectriCruizer’ is £630 or the kit only at £350. Higher powered motors are available for both, but may be illegal for use in the UK (both Cambridgeshire and Suffolk Police were unsure of the law, but 200W is the limit).

The bikes with their motors and batteries were pretty heavy, at 26 kg and 25 kg, which is roughly the weight of four carrier bags of shopping on top of the weight of the basic bikes. Once the battery has run out they are no fun to pedal uphill and this really is the major factor in their usefulness – you must never run out of battery power!

So can they do a useful job? Well yes but they are not intended for a fit cyclist; better to carry 500 g of bananas for energy than 13 kg of battery and motor that will only last 20 miles. The appeal of electrical assistance is to someone who considers five miles a long way to cycle. With one of these kits those five miles can be extended to 15 or 25 miles at a lower level of effort than the five would have taken. Do not exceed the 15 or 25 miles though – the penalty is too high.

The bikes were kindly provided by the local EV Network members Domain of Histon, on 01223 235636 and their web site is at They offer a discount for Campaign members.

Mike Causer