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The Extra Mile

It’s seemingly becoming an all-electric world, so let’s take a look at e-bikes, or pedal assist electric bicycles, which are a growing feature of the British transport scene. If you’re an eco-minded motorist, they should interest you, as an efficient method of independent local transport in place of a car, whilst people of all ages find them a great way of getting about on holiday, and for longer day trips of up to 50 miles.

There’s a wide spread in what you can spend on an e-bike – anything from £500 to £3,000, and good machines are available under £1,500. Let’s get “range anxiety” out of the way first. As always, range is dependent on battery capacity, which may range from 8 to 20 Amp hours for the almost universal 36-volt lithium-ion batteries used, or around 0.4 to 0.7 kilowatt hours (kWh). Batteries weigh only 2 to 4 kilograms, and typically take you from 20 to 80 miles, depending on bicycle efficiency, battery capacity, and riding conditions. For most trips to the shops and back of up to 20 miles, range anxiety is not an issue – and most e-bikes are quite ridable with pedal power alone, if the battery does give up. Most batteries charge fully from flat in 3 to 6 hours, using a charger plugged into a domestic 13-amp power point, and many offer the convenience of being easily removable from the bike for charging. Some owners even like to have a spare battery, costing £200 to £300. Overnight charging suits most people, and electricity costs are low enough to be negligible.

What essential features differ between one e-bike and another? Aside from price, and thus often quality, they almost universally employ BLDC (Brushless DC) drive motors. There are two variants – hub-mounted motors, where the motor sits in the middle of a wheel, either front or rear, or “crank-mounted” motors, where the motor drives the pedal crank, using various forms of power transmission. Crank-drive systems are superior, allowing more sophisticated electronic power control systems that monitor speed and the gradient of the road, and use torque sensors that measure the effort applied at the pedals. Hub mounted motor systems are cheaper, and may offer little more than an accelerator, or simple switch to set one of several levels of power assistance. On flat roads, both systems offer more than acceptable cruising speeds with minimal pedal assistance, but pedalling harder increases the battery range. Both types come with either hub gears or derailleur gearing, which you use in the normal way for different speeds and altering gradients.

There are a number of single speed e-bikes that mostly overcome the need for gearing, but may present more of a challenge to pedal if the battery power runs out. G-Tech’s well-respected City Bike is a good example of a single speed, belt-driven (no oily chains involved) e-bike, but those with ambitions of riding in hilly country will need a bike with a decent number of gears; hub gears are generally preferred, and easier to use, but derailleur gears suit serious cyclists who have previously used them on non-assisted bikes. 

The legal aspects of riding e-bikes require no registration, licence or insurance, but riders must be over 14 years old, the electric power unit may only supply a maximum of 250 Watts, and the maximum speed is artificially limited to 15.5mph. Throttles may only assist the bicycle rider without pedalling up to a maximum speed of 6kph – i.e. for starting assistance only, and beyond speeds of 6kph, the throttle cuts off if the rider stops pedalling. With the cyclist pedalling, the throttle will offer power assistance up to the speed limit of 15.5mph. 

Helmet use is not obligatory, but surely sensible? This is no buyer’s guide to e-bikes, merely a brief appraisal of the principles involved, and how efficient they are. Take your car for a six mile return trip to the shops, library, post office, or even the pub, and even an efficient diesel car will cost you 60 to 80 pence in fuel; with running costs like depreciation and insurance to consider, along with the inescapable high emissions of a cold diesel engine. Using your e-bike, and with a shopping basket, a backpack, or a set of panniers, your costs are 2p in electricity at most, with zero emissions. You’re also helping cut road congestion, avoiding parking problems (although a good security lock is essential), and getting as much, or as little, exercise as you choose!

Victor Harman 

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