Freegen + Magic Drive

Page Last Modified On: July 20, 2026

Grin Technologies is working in partnership with Charge Bike to bring two innovative hub motor technologies to the DIY market of ebike enthusiasts and early adopters. These motors and controllers are in active development with a goal of shipping our first units to early adopters before the end of 2026.

Motor Summaries

Freegen(tm) Motor: The Freegen motor looks like a conventional geared hub motor, but has the disc rotor attached to the planet gears rather than to the motor shell. This provides some unique capabilities.

Zero wheel drag when pedalling unassisted, the motor freewheels perfectly.
When you squeeze the disk brakes, the motor slows down via regenerative braking rather than heating and wearing the brake pads.
Through clever slip control, the regen braking force is automatically modulated by how hard you squeeze the brake lever.

Who's it for? The freegen motor is ideal for people who mostly pedal their bike without assist, but want a motor available for hills and headwinds. You get the benefits of a small and light geared motor that has no impact on your regular riding, and also the benefits of regenerative braking, eliminating brake wear and increasing the range you get from your pack.

Magic Drive Hub: The Magic Drive motor is a rear hub that links the pedal sprockets to the planet gears instead of to the hub. This arrangement puts the pedals and the motor rpms in series, allowing the pedal cadence to be fully independent of the wheel speed.

Provides automatic pedal torque control without adding a torque sensor.
Eliminates the need for shifting gears while you ride. Maintain a constant pedal cadence at all vehicle speeds.
Eliminates the need for derailleurs and shifters (compared to auto-shifting systems that still require all that hardware).
Provides options for back pedal regen braking and back pedal reverse.
Provides an option for freegen braking with a right-side mounted brake caliper.
Freegen braking automatic ABS mode to permit maximum stopping without wheel lockup

Who's it for? The Magic Drive hub has several use cases where it really shines

Trike Users: The ability to reverse via the pedals while still being able to coast while riding forward is truly unique.
Fast Pedalecs: Without the constraint of drivetrain gearing, it is easy to build a bike that you can pedal comfortably even at high road speeds where conventional drivetrains cause the cadence to top out.
Novice Riders: The elimination of gear shifting simplifies the overall learning curve for riding a bicycle. Just pedal and off you go without any need to downshift when you come to a stop, change your assist level on hills etc.
Cutting Edge: For those interested in experimenting with latest tech, this is a very fun platform to explore. The additional combination of a magic drive hub on the rear with a normal hub motor upfront enables all conceivable riding characteristics, and allows both the pedal cadence and pedal torque to be decoupled from the terrain.

Videos

Please see the following videos for a much deeper drive explanation about the core motor technologies.

Specifications for Magic Hub

We have largely decided on the motor that will be used for the magic drive offering. It based on a rear fatbike motor core that weights just over 4kg but because of the stepped planet gears giving an impressive 7.8:1 gear reduction, this has the torque output capabilities we'd normally only see in geared motors of 5.5kg or more.

Parameter	Rear Magic Drive Motor
Motor Weight	4.2 kg
Motor Gear Ratio	7.8 : 1
Axle Length	135mm
Connector Style	L1019
Motor Kv	~8 rpm/V
Internal Clutch	Optional (Yes for freegen brake option, no for coaster / reverse option)

Specifications for Freegen Hub

There are two motors shortlisted for consideration for the front freegen motor offering. The most mature option is a ~3.5kg helical cut geared hub motor, while the second more experimental option is a lighter/smaller 2.5kg motor with a very high efficiency amorphous steel core and an approximately 10:1 gearing. Both options are under active evaluation to vet their suitability, with a preference towards A but a fallback towards B if option A would not be ready in time.

Parameter	Front Freegen Motor A	Front Freegen Motor B
Motor Weight	2.5 kg	3.5 kg
Motor Gear Ratio	>10:1	6.7 : 1
Axle Length	100mm	100mm
Connector Style	Z910	L1019
Motor Kv	7-8 rpm/V	~8 rpm/V
Internal Clutch	Yes	Yes

Kit Package

We will offer the hub motor as a kit with a controller and display included, as those need to be custom programmed for these specific motors. You will have the option to have the wheel laced up at Grin or at your end.

The magic drive rear motor will also come with various sprocket options, disc rotor options, a right side disc calliper mount, chain tensioner, and an optional freewheeling crankset.

Battery Compatibility

The kits can work with 36V, 48V, and 52V batteries, but many off-the-shelf packs will have inadequate BMS circuits. The Magic Drive motor in particular has very high peak loads, and requires a BMS that supports short-term (300-400mS) discharge currents of 75A, even if the average current remains well below this. There are settings in the controller that allow you to reduce the peak current draw from the battery, but this can result in the pedals slipping when you apply a heavy force on the cranks.

The freegen motor will be compatible with smaller batteries and lower current BMS boards as long as it allows regen current to flow in uninterrupted. Most ebike batteries have dual-port BMS circuits and don't have any issues with regen.

Pre-Order

Both the Magic Drive and Freegen motor models are available for pre-order deposits here and here. This deposit will help us with the upfront mold and tooling costs to move from prototypes to production, and also help us gauge the relative interest between the magic motor and freegen motor models so we can plan production volumes accordingly.

Pre-order customers naturally will be first to receive the first units, and they will also get a 20% discount off the final motor price once the kits are available.

How much will it cost?

We will have to determine that later once the first production is finalized and we can properly assess all the financials. It's too early to say now. Whatever the price is, those who put down a pre-order deposit will receive a further 20% off discount.

FAQ

That's so exciting. Should I hold off buying XYZ and wait for this?

Short answer here is no. Existing ebike drives are awesome and work great, and it rarely makes sense to hold off getting something already proven that works well in anticipation of a future product, which may face any number of setbacks and delays.

Is it compatible with thru-axle bikes?

Unfortunately not. These hubs are based on existing geared motors that have a conventional 12mm threaded axle with 10mm flats. They cannot accommodate thru-axles via adapters like our all-axle hub motor.

What if the electronics fails, will I lose my brakes?

If your battery becomes detached or there is a critical failure of the electronics, then indeed the regen braking force on the associated hub will be lost. You would then come to a stop using the mechanical brake on your other wheel.

This is no different than if you get a leak in your hydraulics or snap a brake cable in one of your mechanical brakes, you would switch to using the other working brake instead. If that is a concern to you and you only feel safe with two mechanical brakes, then definitely stick to conventional hubs.

Will it work with XYZ motor controller?

The control of both freegen and magicdrive requires very specialized motor controller firmware. Although the motors themselves will spin up fine with any BLDC motor controller, the actual features of freegen or magic drive won't work. You'd be free to try and develop your own code to implement these things if you are a controller engineer or a highly skilled hack.

If you don't deliver on time or I don't like the final price, can I get my money back?

Yes, of course. The deposit is 100% refundable at any time, no questions asked or explanation needed. Just tell us you are no longer interested and we'll return the funds.

I'm an ebike manufacturer interested in this technology. Will it be available for OEM integration into factory ebikes?

Yes, please send us an email that explains your application and why or how this technology could work, as well as your general willingness to be involved in developing products vs items that are mature and market-tested. Grin or Charge Bike will get back to you with more details.