BQ’s e-bike glossary

Watt are you torquin’ about?

E-bikes and the systems that offer pedal assistance come with a whole new vocabulary. And while navigating Queensland’s new e-mobility laws, it helps to have your head around some of the terms, to avoid being taken for a ride by an e-device retail cowboy! 

Watts, watt-hours, torque, peak power, continuous power, cadence sensors – what does it all mean? 

Understanding the terminology is particularly important when talking about e-bike power. A legal e-bike in Queensland must have a maximum continuous rated power output of no more than 250 watts. That doesn’t necessarily mean the motor can never produce more than 250W. Most compliant e-bike systems will produce above 600W for short periods, which is ideal for hilly areas, toting kids in a cargo bike or for a step-up feature on the local mountain bike trails. 

That’s just one important differentiation – but here is a complete glossary with some explainers. 

Amp-hour (Ah) 

Amp-hours describe a battery’s electrical charge capacity. 

You’ll often see batteries advertised using both volts and amp-hours. Multiplying nominal voltage by amp-hours gives an approximate battery capacity in watt-hours. 

For example, a 36V, 14Ah battery has a nominal capacity of about 504Wh. 

Assistance level 

Most e-bikes offer multiple assistance levels, often with names such as Eco, Tour, Trail, Sport, Turbo or Boost. 

Higher modes generally provide more assistance for a given amount of rider input, but typically use more battery energy. Lower assistance modes can extend range and may provide a more natural riding feel. Most good e-bike systems have at least one dynamic setting, where the system won’t waste energy if you’re just cruising, but it won’t limit the support on offer when you really give it the beans. Top systems let you tune that delivery of support via an app, but in general, the people who get paid a salary to set them do a pretty good job. 

Cadence 

Cadence is how quickly you pedal, measured in revolutions per minute (rpm). 

Some e-bike motors are designed to provide their strongest or most efficient assistance within a particular cadence range. Changing to an easier gear and increasing your pedalling cadence can therefore help some mid-drive systems perform more effectively on steep climbs. 

It is not uncommon for riders new to e-bikes to forego using the gear range, instead relying on the modes of the e-bike system and torque. Not only will this wear out the drivetrain faster, but you don’t actually utilise the performance of the system. 

Cadence sensor 

A cadence sensor detects pedal rotation rather than directly measuring how hard you’re pushing on the pedals. 

On simpler systems, detecting that the cranks are turning can be the trigger for the motor to provide assistance. The result can feel less directly connected to rider effort than a torque-sensing system, although the sophistication of cadence-based systems varies considerably. This is typical of a very simple e-bike system, delivering a disconnected ride. 

Derestricting / chipping 

Derestricting, sometimes called chipping, is modifying an e-bike’s hardware or software so its motor continues to provide assistance beyond its designed or legal limits. 

A bike modified so that its motor continues assisting beyond the legal 25km/h assistance limit is not a legal e-bike for use on Queensland public roads, paths and trails. 

Similarly, software limiting or “locking” a high-powered device doesn’t necessarily turn it into a legal e-bike. The underlying motor and device still need to meet the relevant requirements. 

E-motorbike

A bike that gains forward momentum via a throttle, and not the pedal system. Pedals may be present, but if the throttle assists beyond the legislated 6km/h, or the output or speed limits are beyond those determined by the EN 15194 standard – it is an e-motorbike. This includes electric trail bikes.

EN 15194 

EN 15194 is the European standard for electrically power-assisted cycles, commonly referred to as EPACs. 

Queensland’s e-bike rules use EN 15194 as the relevant standard. Among the key requirements for legal public use are a maximum continuous rated motor output of 250W, pedal assistance that cuts out at 25km/h, and throttle-only assistance limited to 6km/h. 

EN 15194 means much more than a 250W rating. The standard includes safety and performance requirements and testing covering the motor management system, electrical system, charging system and other aspects of the complete e-bike. For consumers, EN 15194 compliance therefore provides a useful indication that an e-bike has been designed and tested against an established set of safety and performance requirements. Look for the compliance sticker! 

EPAC 

EPAC stands for Electrically Power Assisted Cycle. 

It is the terminology used for the type of pedal-assisted e-bike covered by EN 15194. The important word is assisted: the electric motor assists the rider rather than turning the bicycle into an electric motorcycle. 

Hub motor 

A hub motor is built into the hub of the front or rear wheel. 

Hub motors drive the wheel directly rather than transferring their power through the bike’s chain, cassette and gears. They can offer a relatively simple and cost-effective e-bike system and are common on value-focused urban and commuter bikes. 

Most aftermarket hub systems won’t easily comply with the EN 15194 standards, so check for compliance markings. 

Maximum continuous rated power 

This is the important figure behind the 250W limit for EN 15194 e-bikes. EN 15194 is a widely recognised safety and performance standard for electrically power-assisted cycles (EPACs), and is the standard referenced by Queensland’s e-bike regulations. 

Maximum continuous rated power relates to the power output the motor is rated to sustain under defined operating conditions, reaching a point of thermal equilibrium rather than continuing to build heat. 

For an EN 15194 e-bike, this maximum continuous rated power is 250W. The motor may produce considerably more power for shorter periods, such as when accelerating or tackling a steep climb, without changing its 250W continuous rating. 

That’s why saying a compliant e-bike motor “can’t produce more than 250W” is misleading. 250W describes its maximum continuous rated power, not its peak output. 

Mid-drive motor 

A mid-drive motor is positioned around the bike’s bottom bracket and crank area. 

It transfers power through the bike’s drivetrain, allowing the motor to take advantage of the bike’s gears. Centralising the motor and its mass can also provide balanced handling, which is one reason mid-drive systems are common on e-mountain bikes, performance e-bikes and many cargo bikes. 

Motor cut-off 

The motor cut-off is the point at which the motor stops providing assistance. 

For a legal e-bike in Queensland, motor assistance must cease at 25km/h. It is important to remember that this isn’t a speed limiter for the bicycle itself. You can pedal or coast faster than 25km/h; you’re simply doing it without assistance from the motor. Many cheaper e-bike systems will exhibit a lot of drag once the assistance is removed. A high-quality e-bike will still feel much closer to a normal bike, albeit a heavier one. 

Newton-metre (Nm) 

A newton-metre, abbreviated to Nm, is the unit of measurement for torque. 

Peak power 

Peak power is the higher output an e-bike motor may be capable of producing for short periods, such as when accelerating or climbing. 

An EN 15194-compliant motor rated at 250W maximum continuous power may therefore produce considerably more than 250W momentarily. 

Peak power and maximum continuous rated power are not the same measurement, so a peak-power figure shouldn’t automatically be used to determine whether an e-bike meets the 250W continuous-power requirement. Peak power helps you start on hills, keep a heavy load moving for short bursts, and tackle technical climbs on an eMTB. 

Pedal assist 

Pedal assist means the motor provides assistance while you pedal rather than replacing pedalling altogether. 

For a legal e-bike in Queensland, the pedals must be the primary source of power. Motor assistance must stop at 25km/h. You can ride faster than 25km/h, but the motor can’t continue helping you above that speed. A good e-bike system tapers the support off around that point, so it doesn’t feel like you have hit a patch of mud! 

Range 

Range is the distance an e-bike can travel using its battery. 

Unlike a car’s fuel-tank capacity, there’s no single reliable range figure. Rider weight, cargo, hills, wind, temperature, tyres, tyre pressure, surface, motor efficiency, assistance mode and rider effort can all have a major effect. 

Manufacturer range estimates are therefore best treated as a guide rather than a guarantee. And based on the above, the range one rider gets on a given ride may differ from another – even on the same route with the same e-bike system. 

Range anxiety 

Range anxiety is the concern that you’ll run out of battery before reaching your destination. 

The good news? A legal e-bike is still a bicycle. If the battery runs flat, you can keep pedalling – although the additional weight of the motor and battery may make the trip home a little harder! 

It pays to keep an eye on your battery level indicator and moderate your use of the support if range anxiety weighs heavily on your mind. 

Throttle 

A throttle lets the rider request motor power without applying force through the pedals. 

On a legal Queensland e-bike, throttle-only motor assistance is limited to 6km/h. Above this speed, the rider must pedal for the motor to provide assistance. 

This is quite different from high-powered throttle-controlled electric motor bikes that can travel at substantial speeds without the rider pedalling. These are illegal to use in public areas unless they are a registered vehicle. 

Torque 

Torque describes rotational force. On an e-bike, a higher maximum torque figure can help a motor provide strong assistance when accelerating, climbing steep hills or moving a heavily loaded cargo bike. 

But torque isn’t the same thing as power. Motor design, software, gearing and the way assistance is delivered all contribute to how powerful an e-bike actually feels. 

On an eMTB or e-cargo bike, the combination of a higher torque rating (and using the gears of the bike) makes climbing hills easier. The lower gears let you maintain the cadence needed for the motor to deliver the output you need. For e-cargo bikes or eMTBs, expect 75Nm or greater – unless you are looking at lightweight eMTBs. 

Torque sensor 

A torque sensor detects how much force the rider is applying through the pedals and allows the motor system to adjust its assistance accordingly. 

Push harder and the motor can provide more assistance; ease off and assistance reduces. This can create a responsive and natural-feeling ride. A modern e-bike system reacts to how you ride, allowing nuanced input from the rider. If you’re barely turning the pedals over, you’ll have barely any assistance. Push harder, and the pedal-assist system will do the same. 

Some systems will communicate this by percentage of support, with around 400% being in the upper reaches. That would mean you are getting out 4x what you’re putting in – but that will only happen when the torque is high. 

Voltage (V) 

Voltage describes electrical potential. Common e-bike systems use nominal voltages such as 36V or 48V. 

Voltage is only one part of an electrical system’s specification and shouldn’t be treated by itself as a measure of an e-bike’s power or legality. 

Walk assist / walk mode 

Walk assist provides low-speed motor assistance while you’re pushing the bike rather than riding it. 

It can be particularly useful with heavier e-bikes when pushing up a ramp or steep hill. Queensland rules allow throttle-controlled assistance up to 6km/h. 

Watt (W) 

A watt is a unit of power. On an e-bike, watts are commonly used to describe the power produced by the electric motor. 

However, a watt figure needs context. 250W maximum continuous rated power and 600W peak power, for example, aren’t necessarily contradictory specifications. They are measuring different things but using the same way we measure power. 

Watt-hour (Wh) 

Watt-hours measure energy and are commonly used to describe an e-bike battery’s capacity. 

A 500Wh battery can theoretically supply 500 watts for one hour, 250 watts for two hours, and so on – although real-world e-bike range is far more complicated. Your EV or house battery uses kilowatt-hours, a far bigger unit of measurement but the same concept. Your toaster might run at 2kW, which would burn through a house battery pretty quickly – except you don’t tend to use a toaster for hours on end. 

Everything from assistance level and rider weight to hills, wind, tyre pressure, tyre tread, temperature and riding speed affects how far a battery will take you. Some e-bike systems have a nifty range estimator built into the head unit or app. Generally, a larger Wh figure means more energy is available and therefore you have more range. 

For the rules covering where and how you can legally ride an e-bike in Queensland, see Bicycle Queensland’s E-bike laws explained guide.