When planning your electric bike build, one of the first questions you should ask yourself before you pick your conversion frame is…do you want a front wheel drive or rear wheel drive?
In this article we will pick out the pros and cons of both.
If you already own the frame you plan on converting, your task is much easier, you just need to determine if the bike (and your commute) would be better off with front wheel drive or rear wheel drive (or both?).
Picking a hub motor to install:
If you plan on installing a high power motor (over 500W) you are best going with a rear hub. Understand that a high power motor is heavy (up to 25lbs) so when deciding on whether front wheel or rear wheel drive, decide first where you would be most comfortable with all that weight, and how much power you want.
If you go with a geared hub motor (BMC, MAC, Cute, Bafang, etc) its possible to get a powerful motor in a much lighter and smaller package.
When you buy your hub motor or hub motor kit, be sure to specify if you want front or rear drive. Since the spacing is different between front and rear dropout you cannot use the same kit on the front or back. Most people opt to go with a rear hub motor when weighing benefits with rewards, but it all depends on personal preference, and what you want out of the bike.
Front Wheel Drive
All wheel Drive if you pedal! in snow, mud, and rain it can’t be beat.
Keep the rear pedal gears clean, and the same as if there was no motor.
Potential to use any shifting system on the rear including Internally Geared Hubs. IGH’s are sweet. Read our story about Rohloffs on E-bikes here.
Bike is more balanced if battery is in the popular and convenient rear rack.
Harder to smoke motor because the front wheel slips during intense climbing.
Traction problems at low speeds especially off road
Traction problems when climbing off road at low speed
Potentially dangerous if not set up correctly because of front drop outs snapping
Cannot use ultra powerful motor.
Probably requires a torque arm (read story)
Looks clearly like a hub motor up front (not a stealthy as rear drive motor)
Front suspension is not recommended, especially at high power levels.
Can be tremendous safety issue if not hooked up correctly (front wheel locking up is bad)
Rear Wheel Drive
Overall quality of ride is better with a rear drive.
Beefy rear drop outs are harder to break than front forks. (safer!)
Better traction when climbing up hillls offroad.
Limited as to the rear cassettes you can use.
Motor is hidden by gear cassette and rear disc brake, looks cleaner and more stealthy
No issues when choosing suspension forks, front disc brakes, or upgrading to hydraulic.
Installation is more intense than front hub.
Rear hub motor can take up to 7 speed freewheel, so bikes with 8 and 9 speed systems will require either downgrade to 7 speeds, or a slight frame spreading to accommodate 8 or 9 speed freewheel.
Rear disc brake may not be an option, requires fussy fitting if its even possible.
IGH hub (ie Rohloff) is not possible. Read our article about Rohloff on ebike here.
Changing rear cassette is required.
Bike becomes back heavy and unbalanced, especially if battery is rear mounted.
Rear flat tire becomes a huge pain. Recommend upgrading tubes and tires.
All Wheel Electric Drive
For extremists, or for those who don’t like deciding between front and back…you can go with both a front and rear hub motor. Now you have all the power and traction possible. Lets weigh the pros and cons to such a set up starting with the cons:
Heavy…twice the added weight.
Cost…twice the added cost of an electric bike.
Maintenance…twice the chance something will break.
Complex…with two motors you will need two controllers and maybe two batteries.
Efficiency loss…one motor is more efficient than two motors.
Less steatlhy (twice the wires to hide)
All wheel drive!!
Awesome for traction when climbing or on soft surfaces such as snow or sand
Slightly higher top speed, and alot more torque
Cool as hell
Runs cooler for mega hill climbs
Reliability…less of a chance of the bike leaving you…always have a second motor.
Read our extensive write up on Torque arms here.