Now fast and sleek, electric bikes have overtaken their nerdy image. James Daley reports on the current favourites

Not so long ago, anyone who rode an electric bike was considered to beeccentric. But improvements in technology have sparked a surge in the popularity of electric bikes. While just a few hundred were being sold every year at the end of the last decade, the industry managed to shift some 20,000 in 2005.

Furthermore, manufacturers have moved beyond the single-gear, throttle-operated prototype to design a new generation of e-bikes, which have gears and which, in some cases, merely "assist" the rider, rather than do all the work for them.

Dan Hornby of Sakura Battery Company Limited, the largest UK importer of electric bikes, says that one of the key attractions is that this new breed of bike allows you to make short journeys without needing a shower at the other end.

Once you've decided whether you're looking for a bike to assist you, or one that will do all the work, there are a number of other tough decisions to make. Perhaps the most important of these is to consider how heavy a vehicle you are willing to take.

Electric bikes must by law weigh less than 40kg, but the lightest weigh as little as 17kgs - a significant difference if you need to carry your bike up and down stairs every day. Although the material the frame is made of is crucial, the type of battery you opt for can also make a big difference. The old-style lead acid batteries are the most common and by far the cheapest. However, they are also the heaviest. Although replacing a lead acid battery will not cost the earth, it could add as much as 7kg to the weight of your bike.

The most up-to-date bike batteries are either nickel metal hydride or lithium polymer. The latter is lighter, but as much as £200 dearer than its nickel-based alternative.

Weight is not lithium batteries' only advantage, though. Alan Mckeown of Vita Electric in Hampstead, north London, says that they also tend to have a slightly longer life-span and take a little less time to charge. However, Sakura's Hornby believes that the differences are not yet great enough to justify the price differential.

Most electric bikes currently manage about 20 miles on a single charge, regardless of battery type. And with a maximum speed of 15mph (a legal requirement), this tends to be more than enough for most users' needs.

Hornby says that many in the industry have been calling for a lift on the 15mph cap (although most bikes could manage higher top speeds, the ones that are sold in the UK are restricted due to the law). However, given that electric bike riders do not need a licence, do not need insurance, and only need to be 14 to use them, he believes it would be dangerous to relax the rules.

On average, electric bike batteries take about four hours to charge in full. But Mckeown warns that, if they are not used for long periods, battery performance can decrease rapidly.

With demand having increased significantly in the UK, more and more companies - including well-known brands such as Giant - are pouring money into improving technology.

Mckeown says that several companies are looking into powering bikes using hydrogen fuel cells, which would be even more environmentally friendly than electric models (while electric bikes do not produce any emissions, they still consume electricity).

Already, too, the aesthetics are much better than they were just a few years ago, with many of the batteries now hidden inside the frame, rather than stuck to the outside of it. Indeed, the Swizzbee and Sakura's Mustang Chopper are better-looking than the average pushbike.

In the future, however, Hornby predicts that electric bikes will be better-looking still, batteries will last even longer, and the weight will continue to come down.

Electric dreams

* Swizzbee

With its Heinzmann engine,one of the fastest models. Unrestricted, it can get up to speeds of more than 45mph.

Price and weight: £2,500, 26kg

Battery: 24 volts, 7 amp, nickel metal hydride (or 10 amp lithium polymer for extra charge).

Charge time: 3-4 hours

Range: 20-30 miles

* Sakura Shopper

It has a step-through design, plus storage. It's one of the more competitively priced bikes, and comes with a powerful 14 amp battery.

Price and weight: £639, 39kg

Battery: 36 volts, 14 amp, lead acid

Charge time: 8 hours

Range: approx 20 miles

* Giant Twist Lite

One of the lightest bikes. Riders have the option of using their feet, the engine, or a combination.

Price and weight: £899, 20kg

Battery: 12 volts, 6.5 amp, nickel metal hydride

Charge time: 3 hours 50 mins

Range: 18-27 miles

* Dahon Roo El 2006

When it is released in September this will be the lightest bike on the market. A foldaway model.

Price and weight: £1,399, 17kg

Battery: 6 volts, nickel metal hydride

Charge time: 3 hours 40 mins

Range: 30 miles

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