You pay your money and you take your choice but when you purchase an e bike (also known as Battery Bikes) what are you actually paying for? For whatever reason, many of us still feel the need to assess any bicycle based solely upon its purchase price when we have little regard or understanding of the difference in features, technology or materials that can otherwise have a significant impact on its price and performance.
First up is the battery itself. Battery technology is a very dynamic and fast moving field right now. Though many manufacturers will happily quote the nominal voltage of their machines, often what’s more pertinent is the actual make-up of the battery itself since the different technologies vary wildly in their performance and cost. Lead Acid (Pb) batteries are traditional, old school technology. Invariably found on cheaper machines, they penalise the rider through their increased weight and relatively slow recharge cycle times. Nickel based technologies (Nickel Metal Hydrides or NiMH) are lighter than lead acid batteries and are more user friendly although they do suffer from losing their charge over time even when not in use. Lithium based battery technology offers a welcome reduction in weight, increased energy density and by far better recharge characteristics and shelf life. Laptops and mobile phones are now commonly powered by Lithium based cells and since their adoption in these products (which used to use Nickel based cells), overall size and weights have tumbled whilst run times and performance have increased.
Secondly, the way that the motor is controlled can vary. Some, invariably cheaper e-bikes, employ a simple switch which offers no control over the amount of power that is being made available to the motor. Whilst this is a cheap and workable solution, this can make the bike feel awkward to ride and, if being ridden alongside a friend or partner, both riders have to start together else the gap between the two cannot be easily bridged.
An evolution of the switch is the twist grip which allows the rider to vary the amount of power being sent to the motor. This type of control overcomes many of the drawbacks of the switched operation although it is still effectively powering the motor at all times and requires the rider to continually apply some throttle in order to maintain momentum.
By far the most technically accomplished solution is the use of a torque sensor within the crank assembly, or a drop out sensor which measures chain tension. This effectively senses how much effort the rider is having to input and increases or decreases the motorised assistance accordingly so as to preserve the battery’s energy and increase the battery bike’s usable distance between charges. As you encounter an incline or need to accelerate, instinctively the rider will push down harder on the forward crank. The sensor picks up on this torque increase and automatically increases the power to the motor but when on a straight, or coasting downhill, the rider needs no power assistance from the motor to maintain their constant speed (as sensed by no torque being input through the crank) and so the system automatically switched off or decreases the power to the motor.
Motor and battery technology aside, battery bikes then share common features with normal bicycles. Suspension forks and suspension seat posts all aid rider comfort whilst disc brakes or powerful V type brakes increase braking consistency and power which can be an important consideration given the additional weight that an e-bike carries over its non-powered traditional cousins. Aluminium continues to be used to provide lightweight and strong frames and normal, derailleur gears can provide the ability for the rider to optimise their pedal speed with their chosen road speed and conditions and if you are considering an e-bike for a daily commute, then the addition of racks and panniers will be appreciated as will be the inclusion of lights, chain guard and mud-guards.
In conclusion you need to choose the best battery bike you can within your budget, but perhaps more importantly go out and have a test ride, not just of one bike but of several because they all feel slightly different to ride. So many people think that having ridden one sort they will all feel the same and that’s just not true, it’s a bit like thinking that a Mini will feel exactly the same to drive as a Ferrari, they both work as cars but are worlds apart to drive. So go and have a test ride and choose the bike that you feel most comfortable riding – you are more likely to use the bike if you love being out on it, this will make you investment and time spent choosing well worthwhile.