Hub Motor Options

Overwhelmed by all the different motor options? Even though it seems like a lot, we have a well curated list of motor models that allow us to accommodate almost every bike type and power requirement. This page is intended to give a good summary review of each model and how they compare in different applications.

Basic Motor Table

Motor Series	Motor Type	Weight	Notes
Bafang G310 / G311	Geared	2.3 kg (2.5 kg Rear)	Quiet Helical Gears
Shengyi SX1 / SX2	Geared	3.0 kg (3.2 kg Rear)	Quiet Helical Gears
eZee	Geared	3.8 kg	Front, Freewheel or Regen Option
GMAC	Geared	3.8 kg	Rear Regen Only
Bafang G62	Geared	4.9 kg	Fatbike
Crystalyte SAW20	Direct Drive	3.0 kg	Folding Bike (75mm)
Grin All-Axle	Direct Drive	4.0 kg (4.3 kg Rear)	Supports All Dropouts, including Thru-Axle
Nine Cont. FH212 / RH212	Direct Drive	6.4 kg (6.7 kg Rear)	Good Power for Price, if a bit heavy

Our most popular geared hub motor conversion systems are the Mini G310/G311 or slightly larger SX motors for those wanting a lighweight and silent setup,  and the higher end GMAC and eZee kits for those wanting awesome hill climbing torque and regen. For direct drive hub motors that fit standard bike frames, both our  All-Axle hub and the more cost-effective but heavier RH212 / FH212 have been equally popular, but if you have a modern thru-axle frame then it's All-Axle all the way.

In addition to these common options, we also have a number of specialized kits for niche applications; such as the SAW20 with 75mm axles folding bikes, Wheelbarrow motors for material moving, and the G62 motor for fatbike conversions with 170-195mm rear dropouts. For a detailed list on what motors would be compatible with your particular bike frame, have a read of our Bike Compatibility Guide. Here’s a summary breakdown of the current packages that we've put together at Grin, from smallest to largest. 

 

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Crystalyte SAW20

Bafang Mini Geared G3 Series

Shengyi SX Series

G62 Fatbike

eZee

GMAC

Grin All Axle

FH212 / RH212 Kit

Benefits of a Hub Motor

Hub motors are the most versatile and easiest way of converting a bike or trike over to electric assist. Unlike aftermarket mid-drive systems such as the Bafang BBSHD, they don't put any additional stress on your existing drivetrain and operate with complete independence of your pedal transmission. If your chain breaks, derailleur snags, cogs gets loaded in snow etc. the hub motor will continue to propel the bike even when your legs can't. Not to mention the huge advantages of having regenerative braking. 

There is a considerable amount of misinformation in the online ebike space about mid-drive bikes being superior than hub motors. In most cases the arguments are false generalizations, and result of people extrapolating from the fact that most low-cost factory ebikes are hub motors and expensive brand bikes are Bosch or Shimano mid-motors. Unless you are mostly into recreational trail riding and offroad mountain biking, a suitably powerful hub motor will usually serve you needs just as well with far lower maintenance and better dependability.

Have a look at our Why Hub Motors article for a more detailed explanation on the benefits of hub motor systems, especially for commuter ebikes.  

 

Geared vs Direct Drive

Broadly speaking, there are two classes of hub motors, geared and direct drive. 

In a geared hub, the motor spins internally at a high RPM and a planetary gear transmission reduces this to the low RPM of the bike wheel. This allows for a relatively small electric motor to provide substantial wheel torque. Geared hub motors usually weight between 2-4kg and are small in diameter, allowing them to remain pretty discrete on the bike. For a number of reasons, almost all geared motors also include a freewheeling clutch so that the wheel will spin freely and not turn the motor over if you are coasting.

In a direct drive hub motor, the hub IS the motor, so there is no internal gearing. The wheel RPM is the same as the motor RPM. This has enormous advantages in terms of simplicity with no moving parts inside, but in order to produce adequate torque the direct drive motors need to be large in diameter and relatively heavy. They are typically between 4-9kg and over 20cm (8") diameter. Direct drive motors don't have a clutch, allowing them to do regenerative braking, but this also means that there is some small motor drag while coasting as the magnets are always moving past the stator iron.

Pros of Geared Motor	Pros of Direct Drive
⦁ Discrete smaller diameter	⦁ Better high speed efficiency
⦁ Light Weight	⦁ Regenerative braking
⦁ Freewheeling	⦁ Silent operation
⦁ Better hill climbing efficiency	⦁ No moving parts to fail

In general, we find that geared motors are most often preferred by people who value their smaller size and weight, who require a hub with good efficiency during hill climbing, and for whom the ability to coast with zero drag outweighs the benefits of regenerative braking.

Direct drive hub motors generally shine most in applications where high speed is needed, where regenerative braking is useful, where complete silence is paramount, and where the additional motor weight is not seen as too problematic.

The release of our All-Axle motor has shifted the equation for many people, as it is only marginally heavier that comparable geared hubs like the eZee and GMAC. 

For geared motor kits we have the small Bafang G310 (rear) or G311 front, the slightly larger Shengyi SX1/SX2, and the very powerful eZee and GMAC. For direct drive motors we have the premium lightweight and fits-on-all-bikes Grin All Axle hub on one end, and the heavier by value priced FH212 and RH212 from Nine Continent on the other. 

Regenerative Braking?

Regenerative braking involves using the motor as a brake to assist in slowing the bike down without wearing your mechanical brakes. This typically results in a 3-8% increase in your range from recaptured energy and a massive reduction in the frequency with which you need to adjust and replace your brake pads. There is no downside or tradeoff whatsoever to having regen if you have a direct drive hub motor. For some of the geared motors we offer the option of regen or not, and depending on how you feel about freewheeling vs reduced brake wear you may be swayed one way or the other. For more info we recommend watching this video here. 

Our Phaserunner and Baserunner controllers have variable regenerative braking, and there are various methods available to modulate and vary the braking force; from proportional brake levers to bidirectional throttles to back-pedal rotation.

Front vs Rear or Both?

The next big question for hub motor selection is whether to put the motor on the front or the rear of the bike. There is a TON of misinformation on the internet and reddit/endless-sphere in particular which says you should always choose a rear hub motor and that front hub motors are dangerous/unstable/ill-advised. This is completely untrue. Our sales are almost exactly 50:50 split between front and rear setups and customer satisfaction is the same in all cases. The smaller geared motors tend to be more front than rear, while the larger direct drive hubs tend to sell more rear than front.

Usually we would recommend a front hub unless there is a compelling reason to put the motor on the rear since it's an easier installation. There is also generally no problem at all installing a hub motor on a bike with suspension forks, carbon forks or whatever. So long as you have a properly installed torque arm so that the axle rotation is not spreading the dropouts, the pulling forces that a motor puts on a fork are WAY smaller than the forces present when slamming on the front brakes or hitting a pothole.

The benefits of a front hub are as follows:

• No conflict or change to your drivetrain
• Ability to use internal gear hubs on the rear
• Simpler installation
• Better weight distribution if battery is on the rear

The main downside of a front hub relates to the fact that on most bicycles, a majority of the rider weight is on the rear wheel rather than the front wheel, so the amount of traction available on the front wheel is not as high and it can be possible for the wheel to skid out at full throttle. Riding on pavement this only becomes an issue at fairly high power levels (>1000 watts), but when climbing hills on loose gravel or dirt roads, you can end up with the front wheel skidding pretty easily even at fairly modest powers unless you deliberately lean over the handlebars.

Downsides to a Front Hub:

• Limited traction for high power (>1000 watts) or loose gravel roads
• Not entirely discrete, especially direct drive

For rear installations, the motor is better tucked away with the cogs and pannier bags, and it is possible to run at very high torque levels without losing traction. However, the motor must also tie into the mechanical drivetrain.

Benefits to a Rear Hub:

• Looks most discrete
• Possibility to have torque sensor integrated in motor, without need for bottom bracket sensor
• Almost no limit to power capability in terms of traction and handling

Downsides to a Rear Hub:

• No opportunity to use internal gear hubs
• Drivetrain compatibility concerns (freewheel vs freehub, 7,8,9,10,11 speeds, road vs mountain cassettes)

From our perspective, the decision of front or rear motors is fairly easy. You'd generally choose a front hub for ease of installation and versatility, unless your vehicle design doesn't allow it (eg tadpole trike), or your ride situation would have traction issues (dirt road hill climbing or very high power), or you just figure that for aesthetic or personal reasons you want the motor on the back. Fortunately there are far fewer compatibility issues with rear hub motors now that all our motor options use cassette freehubs and proper disc alignment. Historically when most rear hub motors used threaded freewheels it would often mean a downgrade of the bicycles drivetrain. 

Dual Hub Motors

Dual front/rear hub motors on a bike is an excellent way to achieve higher power levels than a single hub motor can produce, and is especially useful in cargo bike or load hauling applications. When you run two brushless motor systems on the bike, each motor requires its own motor controller (there is no way around this) but the throttle signal would typically be split to run both motors equally. For more specific information on setting up a multi-motor system, see our multi-drive info page here.

Wheel Lacing

Grin used to source most of our hub motors prelaced overseas by eZee, Crystalyte, Nine Continent etc. and only offered custom hand-built wheels as a special option. But we found the quality control of prelaced hubs hard to guarantee, and even if we hand tweaked the spoke tension and truing of the prebuilt motors before shipping we still had a fairly high rate of customers experiencing spoke breakage. Meanwhile our own hand built wheels had a nearly flawless track record by comparison.

As a result of this experience, we now exclusively stock only unlaced bare hub motors and do all of our kit wheelbuilds by hand, using the best quality Sapim 13/14g butted spokes and applying all the expertise we've acquired over the years to make nearly bombproof wheels. It means a built-up kit form Grin will cost more than most other hub motor suppliers, but in exchange you can have a vast choice of rim options and full peace of mind that you won't be randomly popping spokes down the road. 

If you want the kit at a budget, you can absolutely do the wheel lacing yourself and order just the hub motor and spokes and either reusing your original rim or getting one locally. This also greatly reduces the shipping cost to places like Australia and Europe, as the kit can be sent out in a much smaller box size. 

Power Rating

Most in the ebike industry erroneously catalog and reference motors as having a certain power, and you will see people endlessly talking about having an ebike with a 250 watt motor, or a 500 watt motor, or a 1000 watt motor. This is neither accurate nor meaningful. The power capability of an electric motor depends on both the RPM it is running at AND on how long you need it to run for. It is not a single number and it can only be represented by a full table of values for different conditions.

Every motor also has a reasonable set of conditions where the continuous output power is in fact 250 watts, and so for those who require a 250 watt power rating on their motor to facilitate compliance we provide a laser engraving service. Please do not limit your motor choice based on a perceived motor power rating. Make sure you choose a motor that has sufficient torque capability to move you up the grade hills you expect to enounter.  

À-la Cart or Premade Kit Bundle?

All of our hub motor models are available by themselves, and you are free to purchase the parts you need to build up a kit. But for most people it is easiest to use one of our conversion kit bundle pages where you can pick and chose among all the compatible options of controller, battery, torque arm etc.  All motors are available to purchase as a Barebones Kit, a SuperH Kit, or a CA3 Kit. For details on that see our Kit Types page.