Electric motor: choosing your equipment

Electric motor: choosing your equipment

When you want to equip yourself with an electric bike motor kit, many questions arise and finding all the answers is not easy: the internet is full of scattered and sometimes contradictory information. In the following lines we will condense a few answers.

The question of the electric motor location is one of the first questions you ask yourself.

In general, front electric motors are less powerful, used for light assistance and/or smaller bikes such as a folding bike that can easily be carried on the train or in the lift.

A rear electric motor kit will provide more power and torque, for bikes designed for long rides or very hilly paths.

Here are a few answers:

Why do Nine Continent electric bike motors seem a bit heavy?

Rear motors are of the Nine Continents RH205S type: these are direct drive motors, with no reduction system. In exchange for the higher weight than a geared motor, the main advantage of this type of motor is that it accepts high power, up to 3000W, without modification!

It opens easily and some enthusiasts take the opportunity to drill the side cover and increase the cooling required by very high power. It is little known in Europe but it is the most popular in North America because of its ability to absorb anything without flinching. Modified, it even won the famous Pike's Peak race.

A RH205S motor opened after 10000km: the inside is hyper clean, like new. Note that the motor opens easily after removing 9 screws:

On its side, a geared motor of the 8FUN type is light... Because it has a rather fragile nylon gear system: the motor will not run at 1000W for long without trouble: the probability of destroying the nylon parts is 100%. 

Also note that many 8FUN motor models are almost impossible to open (even with the special tool): it is a bit of the cheap disposable Chinese mindset, not designed for maintenance or repair. These are small motors well known on the European market where the oil lobby managed to impose a legal power of 250W, suitable for a folding bike but unusable for people looking for a real alternative to the petroleum vehicle... The end of fuel! 

An 8FUN motor (barely) opened: everything is bathed in a black, foul-smelling grease:

Despite the grease, the planetary gears did not survive a power of 1300W (which makes the 9C purr!):

What about mid-drive motors?

These motors are beautiful pieces of technology and fit into the bottom bracket. This makes it possible to offer (very expensive) bikes that are less in the "electric scooter" spirit and more in the assisted bike spirit (the choice of a cyclist who wants to keep pedalling): one or more sensors manage the assistance by making sure the cyclist is pedalling and modulate the assistance according to their effort. These beautiful mechanical parts have a high cost, are complex and put strain on the bike's drivetrain (chain, cassette).

Why are Chinese motors inexpensive?

Given some exorbitant prices here and there for certain integrated electric bikes, the low price of Nine Continents electric bike motors distributed by Power-E-Bike may puzzle the potential buyer, who will wonder about quality.

If it's cheap, it's no good, right?
That's not exactly it, we will see below.

China being the big supplier of electric motors for bikes, the most frequently used motors come from there. In 2010 China had 200 million electric bikes and production is around 10 million per year.

The Chinese need reliable motors, with variable power (from small folding bikes to delivery tricycles) and also inexpensive.

In addition to the domestic market, China also supplies Europe and the United States. With a motor production counted in tens of millions each year, economies of scale are very significant and the price of these motors is hyper competitive: initially intended for the local market, delivered to the international market the price seems derisory by Western standards.

In Europe, moderate-power, Europeanised 8FUN Bafang type motors (<250W) are very present in integrated products or "legal" kits. In North America it is rather the Nine Continents that is the king of the market thanks to its price, reliability and ability to withstand high power: the legislation is less restrictive!

In (almost) all cases these Chinese-origin motors are hub motors, i.e. integrated in the wheel, allowing simple installation on almost all types of bikes, even the most specific ones such as small folding bikes, recumbent bikes, trikes, cargo bikes...

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