What’s The Best Type Of Ebike Motor?

The answer depends on intended use and how much you’re willing to spend.

Mid Drive Yamaha
Center-drive motors offer the most natural-feeling pedal assist, but come at a premium price.Jeff Allen

The best ebike motor configuration depends largely on what you plan to use the bike for, followed by budget. With those in mind, your choice is easier. For this article, we’ll consider the top power rating to be 750W (there are more powerful motors, but 750W is the current federal limit for ebikes).

Front Hub Motor
Front hub motors are simple and affordable, but lack the power of other drive systems.Jeff Allen

Up Front

Front hub motors are usually the most affordable, due to power rating and simplicity. The most common offerings are 250–350W, which require fewer magnets and less copper wire, holding cost down. There are 500W and 750W available, but price and weight both increase. With no freehub/freewheel to design around, and only one common fork dropout spacing of 100 millimeters, this layout simplifies manufacturing, inventory control, and DIY kit conversions. Flat changes are also slightly easier to execute compared with a rear-drive bike.

The big drawback is power. Front hub motors tend to have the least torque and power. Driving the front wheel by motor and the rear by human can create a kind of push-pull feeling that is unnatural, and steering can also be affected. Suspension forks are not recommended.

While some front motor advocates cite better front/rear weight distribution as a plus, that benefit is canceled out by potential adverse handling effects, in our opinion.

Budget urban commuting and casual pavement riding are where front hub motors shine—when big power isn’t warranted (exceptions: tricycles, where the front motor’s drawbacks are less pronounced).

Rear hub motor Aventon
Rear hub motors pack a powerful punch, but can be a hassle if you get a flat rear tire.Aventon Bikes

Out Back

Rear hub motors have a power advantage, as the rear dropouts can stand up to the greater torque and 500–750W motors. In the US, where the Class 1 limit is 20 mph (rather than the European standard of 25 kph, or 15.5 mph), this extra power is a plus. And that power becomes a must for 28 mph ebikes. The way power is applied directly to the rear wheel makes rear motors ideal for use with a throttle.

Rear motors are more expensive than front motors, as complexity increases with the need for a freehub/freewheel. Variations in rear dropout spacing and axle types can make it a nightmare for DIY conversions and can lead to broken spokes, even with heavy-gauge ones. The weight of the hub motor makes it ill-suited for full suspension, hampering bump performance via added unsprung weight. And rear flats are a nightmare.

Rear motors are best for riders wanting or needing more power, or those looking to incorporate a throttle. There are also some new electric road bikes with small 250W rear hub motors that can be very stealthy with an integrated battery for a clean, traditional appearance. The low power isn’t an issue in this segment, where the rider wants to still be the main propulsion.

Why Not Both?

There are a few bikes with both front and rear hub motors. The power sticks to the usual numbers discussed previously, with the rear hub packing more watts than the front. Electric motors are effectively tuned by the wire gauge and how it’s wound. Single-motor bikes usually split the difference between torque and speed, but a dual-motor system allows the rear to be optimized for big torque to get you going, before handing the drive over to a front hub tuned for speed. Interestingly, this approach can increase the battery range over a single motor.

Using two motors means increased cost and weight, and getting a dual-motor system to work in harmony is complex. It’s the worst configuration regarding flats. So what’s it good for? Heavy loads on cargo bikes. There are some mountain bikes that use this system for all-wheel-drive traction, but its drawbacks often outweigh the traction benefit.

Bosch-eBike PerformanceLineCX
Bosch’s Performance Line CX center-drive system.Bosch eBike Systems

Stuck in the Middle

Center-drive systems offer a number of advantages, and are widely considered to be the best option. Foremost is their energy efficiency, typically pushing into 75-plus miles per charge in their lowest mode. Since they drive the cranks, just like a human-powered bike, they offer the most natural-feeling assist—which makes them the choice of more performance-oriented bikes, especially given their lighter weight.

The motor’s placement on the bike means full-suspension bikes aren’t penalized by added unsprung weight. And when coupled with a downtube-mounted or integrated battery, the extra weight is centered on the bike. This style also allows the motor to amplify its effective torque through the cassette’s gear range (just like people do), and provides more wheel options. Flat repairs are as easy as on a traditional bike.

Unfortunately, center drives are the priciest configuration, and typically require more regular maintenance. Q-factor (the distance from the outside of one crankarm to the outside of the other crankarm where the pedals attach measured along the bottom bracket spindle) can also be an issue, as the motor placement between the crankarms can make for a wider Q-factor. Center-drive systems can also put additional stress on some bike components, and changing gear ratios is not always an option, depending on the system.

While there are center-drive motors offering throttle assist, a rear hub drive is better for the application, and trikes typically stick to hub drives to keep cost down.

So what’s center drive good for? Just about everything. It’s almost mandatory for performance mountain and road ebikes and is good at most everything else, if you’ve got the money.