Electric bike motor: everything you need to know to make the right choice

It's possible to convert your bike into an electric bike! After all, when you love your bike and feel good on it, why change? Electrifying your bike witha conversion kit is an increasingly popular solution, and a good alternative to buying an electric bike. However, it's not always easy to choose an electric bike motor. Between the different types of motor, the power expressed in W, the torque expressed in Nm, it's easy to give up for lack of knowledge. In this article, we explain what you need to know to choose the right electric bike motor. Conversion kit, price of electrification, characteristics of the different types of electric motor... You'll soon know everything there is to know on the subject!

When you want to ride an electric bike, your first instinct is to buy one. However, conversion kits are now available to turn a conventional bike into a super-electric bike.

These kits include all the parts needed to upgrade your traditional bike. In general, you'll find at least an electric motor, a battery, sensors, cables, a screen and the screws and bolts required for assembly. Some kits also include a braking system more suited to electric-assist bikes, or an adapted crankset.

You may be hesitating between buying an electric-assist bike and a conversion kit.

The first difference, and the one that generally determines the choice, is the price. Electric bike conversion kits range from 500 to 1000 euros, so it's clearly a less expensive solution than buying a good-quality EAB.

From an ecological point of view, it's also a better idea to buy only what you need to electrify your bike than to buy a VAE, as it saves precious resources.

But, even if it's a good choice economically and ecologically, how do you actually go about installing a conversion kit? The operation can be carried out by anyone... in theory. In reality, however, you need to be used to DIY. If you haven't touched a screwdriver in ten years, it's best to trust a professional mechanic. It'll save you a lot of trouble...

Opting for DIY? Bravo! To make installation easier, conversion kit manufacturers use specific colors and shapes to help you identify the various parts.

Not all kits are compatible with all bikes. It is therefore advisable to find out in advance whether your bike can be fitted with a conversion kit. 

Another point to watch out for: traditional bicycles are not designed to go as fast as an electric bike, or at least not all the time. So you'll need to make sure that the braking system and transmission are up to the job. Your safety is at stake.

If the general mechanics of your bike are already outdated, opt for an electric bike instead - don't take any risks.

A bike fitted with a conversion kit is no longer covered by the manufacturer's or vendor's warranty. This modification is considered too important for the warranty to remain valid.

As a result, in the event of an accident, the insurance company may refuse to cover the damage. To be insured, you would need to have your bike certified, but this is a very costly operation, and there are few organizations offering this type of service.

Your bike will also be harder to sell. Buyers may be reluctant to purchase a bike that has undergone such a transformation, even if it was carried out by a professional.

If you simply want to replace the motor on your electric-assist bike because it's failing, or because you'd like to upgrade to a more powerful one, the choice is quick: opt for the same type of motor, and if possible from the same brand (Bosch, Shimano, Yamaha, Bafang are the leaders in this field). To help you make the right choice, a comparative article is dedicated to Bosch and Yamaha electric bike motors.

For those who want to electrify their muscle bike, we give you a quick explanation of the different types of bike motors.

This is the type of motor found on entry-level electric-assist bikes or on city bikes. They're clearly not the most efficient, but they're very practical for urban riding, where the cyclist has to stop and restart frequently because of traffic or traffic lights.

To put it in a nutshell, a sensor measures the wheel's (and therefore the bike's) rotation speed. Electric assistance is more powerful when the bike is going slowly, and weaker when the bike is going fast. Less natural assistance, but very practical for stop-and-go situations.

Some manufacturers offer kits that can be easily installed on the front wheel. This is less technical than installation on the rear wheel, since you don't have to deal with the transmission. It's also less complicated than installing a pedal motor.

The system is the same as for a rear-wheel motor: a sensor measures speed and provides inversely proportional assistance. Beware: a front-wheel motor requires a little mastery, as it can be surprising to be driven by the wheel that is also the steering wheel. Be very careful when choosing this type of electric motor.

This type of motor is found on sporty electric bikes and high-end bicycles. Here, the sensor measures power output and provides proportional assistance. The idea is more to boost the rider's natural power than to assist in slow phases. It's a real pleasure to ride, because you get a real feeling of fluidity. It makes you feel particularly powerful.

Like the others, there are obvious drawbacks.Maintenance is more difficult, and this type of engine puts much greater strain on the transmission. In the case of a conversion kit, you'll need to ensure that your chain is in good condition to cope with such power.

To compare two engines, the simplest and most reliable way is to look at the torque developed, expressed in Nm (Newton meters).

Engine torque is the force exerted by the engine on the wheel. It is most pronounced when starting off or at low speed. Once the bike is underway, torque is less pronounced.

To put it another way, let's start with your own cycling experience. You've probably noticed that the hardest part is starting up. When the bike is stationary, you have to use your thighs to get it moving. You have to push hard to get going. But when you're at full speed, it's easy enough to pedal. The motor feels exactly the same.

So you can see why low torque is good enough on flat ground, and why high torque is needed on more uneven terrain.

Your choice should be made according to your use. For urban use or a stroll on flat ground, 40 to 50 Nm are more than sufficient. For sporty outings on rough terrain, don't be afraid to go up to 100 Nm.

Obviously, as with a car, the more powerful the engine, the more energy it will consume. To choose the right conversion kit, you also need to take a look at the battery capacity: 300 Wh are enough to feed a weak engine, while a powerful engine will need at least 625 Wh.

Be careful if you choose to electrify your bike ! Your riding sensations will inevitably change, so it's important to adapt to them before taking it out on the road.

Start, for example, by testing off-road in a quiet, open area. Familiarize yourself with the power of electric assistance and how it affects the bike's behavior. We wish you all the best on your (not really) new augmented bike!