JARGON BUSTER

PEDAL-ASSIST/ PEDELEC (PEDAL ELECTRIC CYCLE)

Terms that describe e-bikes with motors that only provide assistance when the rider is pedalling. As soon as the cranks stop turning, the power cuts off. This is the only type of e-MTB that can be legally used on UK trails.

MOTOR

The electrical system that provides power. Can also be called the drive unit or engine. Motors built into the front or rear wheel are common on cheaper hybrid or commuter bikes, but mountain bikes generally use a ‘mid-drive’ system, where the motor is mounted at the junction of the down tube and seat tube, replacing the bottom bracket. Here, it forms a part of the bike’s suspended mass and lowers its centre of gravity, which can improve handling and suspension performance.

BATTERY

Normally removable (for charging or to fit a spare), the battery can be integrated into the bike’s down tube or sit on top of it. It’s usually connected to the motor using wiring with a waterproof connection.

CONTROLLER

Frequently mounted on the handlebar near the left-hand grip, the controller’s buttons can be used to toggle between motor modes and to cycle through different screens on the bike’s display unit, if fitted.

DISPLAY UNIT

Sometimes this is mounted on the bar or stem, but it can also be integrated into the bike’s top tube or elsewhere. It can display multiple bits of useful information, including battery charge and current mode, along with speed, predicted range and cadence.

MODES/SUPPORT LEVELS

Most motors feature user-programmable or selectable support levels. These change the amount of power and torque supplied. ‘Eco’ generally provides the least support, while ‘Boost’ or ‘Turbo’ unleashes full power.

WALK ASSIST

A feature most e-bikes have, where they’re able to propel themselves at low speed without the rider pedalling, making it easier to push them up steep sections.

WATTS (W)

The measurement of e-bike motor power.

PEAK POWER

UK law limits motors to 250W of continuous, standard power. Many manufacturers claim peak power outputs higher than this, but this output is only in certain circumstances and for short periods. If a motor doesn’t deliver as much power as expected, it may be because it’s reached a 250W continuous peak and is ‘throttling back’ to avoid exceeding the limit.

SUPPORT PERCENTAGE

How much the motor augments a rider’s pedalling inputs. A drive unit with 100 per cent support will essentially double the rider’s power – so if they put out 50w, the motor will also provide 50w, amounting to an overall system power of 100w. Support percentages are directly related to motor peak power, and usually in the region of 300 to 400 per cent.

TORQUE

The amount of twisting or rotational force the motor provides. A higher torque value, given in Newton metres (Nm), will make the motor feel more powerful.

WATT HOURS (WH)

A standard measure of electricity, equivalent to the power consumption of one Watt for one hour. E-bike battery capacity varies greatly, and as technology improves so does energy density, where more power can be contained within the same space.

OVERRUN

Motor assistance usually continues for a short period after the rider stops pedalling. This is called overrun and can be useful on technical climbs, where you need to change your pedal-stroke timing to avoid ground strikes.