Grin Kits

Grin Kits

Brompton Kit

The brompton is among the most iconic folding bikes in the world and has earned a well deserved reputation for its clever design. We have both geared and direct drive motor front options specially made for the Brompton fork which allow you to convert your Brompton into a high-performance machine.

eZee Kits

eZee produced one of the first modern high torque geared hub motors in the ebike space that was fully compatible with disk brakes and dropout spacings, and have continued to update their powerful motor design. They are especially well suited for applications that require good hill climbing capabilities.


The front and rear 212mm motors from Nine Continent are our go-to economical direct drive hub motor. They have many design upgrades over the classic 205mm generic chinese hubs and are an excellent choice when reliability is paramount and weight is not a concern.


The small G311 front / G310 rear motors from Bafang are well suited for those wanting light and discrete conversion for moderate assist levels. A high reduction helical gear set allows these tiny motors to deliver a surprising punch without any of the buzzing noise commonly associated with small geared motors.


The GMAC motor is Grin’s customization of the powerful rear MAC motor, modified to run without a clutch for regenerative braking, a huge plus for cargo hauling applications. A round axle and integrated torque arm allow for powerful regen without risk of axle spinout.

Marine Kit

We’ve also adapted our All Axle hub motor with special high RPM windings and mounting hardware to power propeller shafts in marine applications. This system is primarily geared at those retrofitting sailboats with aging 8-12 horsepower inboard diesel engines. This kit is currently in development / pilot stage.


These geared motors fit somewhere in between the tiny G31’s and the more powerful eZee hubs in terms of size and power, and are a highly recommended all-around motor for most conversion jobs. They have a single stage helical planetary gearing to keep the noise down and have been among our most reliable geared motor models to date.


We designed a retrofit kit for wheelbarrows as well using a motor with a super high 30:1 gear reduction ratio. This kit includes special mounting brackets and hardware to readily retrofit almost any wooden handled wheelbarrow with an electric motor that can pull loads up the steepest hills with ease.