You are thinking of converting your bicycle to electric but aren’t sure where to start. This Electric bike conversion guide will explain how you can add electric assistance to your bicycle.
It can be very rewarding to convert a bicycle into electric assist if you are prepared to make the leap. A conversion to an electric-assist bicycle can be a rewarding experience. It is also cheaper than buying an ebike from a manufacturer.
Let’s assume you have an old Trek and Cannondale mountain bikes in the shed. A decent mid drive 26 inch ebike conversion kit with battery will typically cost around PS600 (780). This is a significant savings when compared to purchasing a mid-drive electric bicycle that’s been factory-built.
While the Decathlon E-Stilus looks great, you won’t see much difference from PS3000.
Converting a bicycle to an electric motor is not something that everyone can do.
It is also important to remember that an retro-fit motor for electric bikes may not be as reliable over the long-term than a Bosch/Shimano step motor found on factory-produced bikes.
You need to consider your intended use before you can choose the motor that is right for you.
If your home is flat with few inclines then a small geared motor hub motor will be sufficient. But if your home is in an area of steep hills then a mid drive would be more appropriate.
The final decision will depend on your personal needs. Both motors have their place on an e-bike, but it is worth noting that mid-drives are generally more efficient than small hub motors.
Hub motors for direct drive
The direct drive hub motor motor is the simplest type of electric bike propulsion. It is made up of an outer shell and a large circle of powerful magnets.
Motors drive the wheel directly by running when the motor is turned on (hence the name). Simply put, the wheel is a motor with a shaft attached so that the shaft (the body of the motor) spins instead.
This is a simple design but it comes with a price – the motor must be very large and heavy to produce enough power. A smaller motor spinning slowly won’t produce enough torque. The speed your wheel needs to turn is very slow so the motor should be as large as possible to produce torque at low speeds.
The positive side is that direct drive hub motors can handle a lot more power and are inexpensive. If you are looking to buy a high-performance electric bike for a low price, a large hub motor might be the best option.
Geared Hub Mower
Motors with small geared hubs are more efficient than motors with direct drives. A planetary gear reduction system connects the motor case to the stator. Each rotation of the motor case makes it spin much faster. This allows for the motor to operate at higher speeds (and is more efficient), while still allowing it to spin at a slower speed.
Another benefit of a geared motor hub motor is that there is virtually no resistance to pedalling if it is turned off or runs low on power. This allows you to pedal just like on a regular bicycle.
While geared motors are generally maintenance-free, it is possible for the nylon planetary to wear down over time if you do a lot. These gears are relatively inexpensive and easy-to-replace.
Front Hub motor vs Rear Hub Motor
Front wheel conversion kit for electric bikes
There are pros and cons to installing a front or rear hub motor. For electric wheels, the front hub motors can be more easily fitted. You don’t need to worry about changing out gear cassettes or freewheels.
The best option for a front-wheel conversion is a small, geared motor hub motor. These motors are small, lightweight, and produce decent torque.
You can buy larger, direct drive front wheel electric bicycle kits. Although they are typically more economical and more powerful, the larger motor can make it difficult for them to fit onto bikes with disc brakes. They are also much heavier and less efficient.
The pedal assist is another benefit of a front hub motor. This means that the bike can be driven by both wheels when you use it. The electric front wheel gives you assistance, but you pedal to power the rear wheel.
For off-road riding, electric front wheels can be a problem as they have a tendency spin on bumpy ground. This is especially true when climbing steep hills.
Rear Wheel Electric Bike Conversion kit
A rear wheel hub electric motor is often the best option to add electric help to a bike using a conversion set. Removing the rear wheel requires a bit more work. You will need to use a special tool.
A motor pushes rather than pulls you (as a front motor). A smaller geared motor at the rear of your vehicle will appear more discrete.
Rear hub motors have another advantage: they can be used on uneven terrain much more easily. The rider weight is all concentrated on the back wheel so wheel spin is significantly less.
This set-up has one problem. It can be slow to replace an inner tube in case of puncture. I highly recommend a Schwalbe Marathon Plus puncture resistant tire to reduce the risk.
Mid-Drive Motor
The preferred drive system for more expensive electric bikes is the mid-drive motor. These motors are more efficient and produce more torque than hub motors.
It can be complicated to fit this type of motor. To make installation easier, the bottom bracket must be removed from the bike. After this is done, it’s easy to move on. Keep in mind that most middrive kits only fit standard threaded bottom bracket shells measuring between 68mm and 73mm wide, and about 33.5mm dia.
A mid-drive system, when installed properly, will give your bike a look and feel similar to an expensive ebike.
Mid-drive motors come with a couple of drawbacks. They have a higher pedalling resistance and require periodic maintenance, such as tightening the motor. There will only be one chainring at the front.
Mid-Drive vs. hub motor
All the above information being considered, it comes down to your budget as well as the type of riding that you intend on doing.
I have found that small hub motors can be a lot easier than mid-drives long-term. The pedalling resistance is another thing to be aware of. With the motor off, both the direct-drive motor hub motor and mid-drive motor produce significant resistance.
Mid-drives perform better when climbing hills. A 250w Bafang Bafang SBBS01B will produce close to 100% more torque that a geared hub motor.
Hub motor kits look more DIY. They will have an external controller (usually stored in a frame bag), a pedal assist sensor, and lots of wiring that needs to be tidied up. Mid-drive motors are cleaner looking and more neat.
Conclusion
A small, geared hub motor will provide a little help when you’re trying to climb hills but allow you to pedal on your own for most of the time. Mid-drive might be the best choice for you if your goal is to be able climb very steep climbs easily.
