FH212-RH212

Background

The FH212 (front) and RH212 (rear) motors are an export-model motor from Nine Continent, one of the largest supplies of generic hub motors used in mass-produced chinese ebikes and scooters. Nine Continent has been around a long time and was one of the earliest suppliers of the generic 205mm direct drive motors that swept across the ebike and scooter scene in the mid to late 2000's.

In 2011 we had them improve their original FH205 motors with thinner 0.35mm laminations, a thermistor temperature sensor, and statorade injection ports which we sold for many years as the 9C+ 2705, 2706 etc.   But the mechanical design of these motors was a poor fit on bicycles, with inadequate disk rotor clearance, a vulnerable end cable axle exit, and no support for cassette freehubs. In 2018 they came through with a slightly larger FH/RH212 motor based on a different core structure and design that better conformed to our bicycle fitment requirements. 

Features

These motors have a number of improvements over the generic Chinese looking DD hub motors:

	More Torque The rotors in these motors are slightly larger in diameter, 212mm vs 205mm, allowing for more magnets (26 pole pairs vs 23) and a great torque generation per magnet. That results in a more powerul and torqy hub than a 205mm motor of the same width
	Plenty of Disk Rotor Clearance The shape of the motor shell provides much more room for disk calipers to fit witout rubbing against the side plate and requiring spacers and shims to align. As well, the position of the disk rotor is where it needs to be (10mm on the front, 15mm on the rear)
	M14 Axle with Side Cable Exit 14mm axle has much greater spinout resistance both with and without torque arms than the 12mm axles which were more common. This is especially important in our Grin setups that make extensive use regenerative braking.  In most generic DD hub motors the cable comes out the end of the axle, leaving it vulnerable to damage in accidents and complicating the installation and exchanging of axle hardware since you have to slide the washers and nuts over the connector to replace them. In the H212 motors, the cable comes out of a diagonal hole through the side of the axle, better shielding it from damage and keeping your axle hardware replaceable.
	L10 Connector The phase wiring on these motors is terminated with the 10 pin high current locking motor connector which integrates the hall wires, temperature sensor,  and phase leads into a single reliable and water-tight plug.
	Statorade Compatibility: The sideplate is well sealed and has an access port through one of the disk holes for injecting statorade to improve thermal performance and heat dissipation.
	Cassette Freehub: Most importantly, the rear motors do not have a threaded freewheel but use a proper Shimano HG compatible cassette freehub system, allowing you to use standard 8, 9, 10, and 11 speed mountain cassettes for use with modern drivetrains. Most generic motors still use a threaded freewheel, and are sized for just 6 or 7 speed freewheel clusters.

Applications and Uses

This motor is well suited to ebike builds needing a powerful and reliable direct drive hub motor at value level pricing but still with decent bike compatibility. For a good look at example bike builds using this motor have a browse of our Customer Project Gallery. The weight penalty of 6.5kg is significant however, making it not for everyone.

Winding Speeds

We stock the FH/RH212 motors in two winding speed options which to cover most bases; a standard 7.5 turn wind (8.1 rpm/V), and a faster 6 turn wind (10.2 rpm/V) . In general the standard wind is primarily used by 26" and larger wheels while the faster wind is for smaller 20" wheel sizes, but it is perfectly fine to choose to lace any winding in any wheel size depending on your desired speed for a given battery voltage.  The fast winding option is especially good for those wanting a peppy system while sticking with the common 36V battery packs. The table below shows the unloaded speed of each winding in different wheel sizes and battery voltages as a handy reference. 

The actual cruising speed under any kind of load is going to be less than this value, and we recommend using our motor simulator for exact performance details of any given combination of motor, battery voltage, and controller model.

Motor Power

The power output capability depends on the RPM at which the motor is being run, the amount of air cooling available, the ambient temperature, and how long you consider it to go. The table below shows the expected power capabilities assuming room temperature atmosphere and a passing airflow consistent with the wheel being laced in a 26" wheel. The continuous rating is the power that will result in a steady state motor core of 110 oC, while the 5 minute rating is the power level it can sustain for 5 minutes starting from 60oC before the core reaches 110 Celsius.

For a more detailed understanding we recommend using our motor simulator or trip simulator applications to properly predict the capability of this motor in any specific usage scenario.

Documents

RH212 / FH212 Documents

RH212InstallManual_Rev1 (463.19 kB)

FH212 Motor Dimensional Diagram (74.86 kB)

RH212 Motor Dimensional Diagram (73.65 kB)

FH212 3D CAD Model (7.33 MB)

RH212 3D CAD Model (7.16 MB)

Videos

Availability

The RH212 and FH212 motors are available as stand alone hubs, or as part of a complete kit with a controller, battery etc. 

Issues

These motors have been relatively robust and reliable, and a solid mainstay of our conversion kit offerings for many years. We were nervous about the quality of the generic cassette freehub but they've proven to be almost completely trouble free. However we have seen a few failures related to the generally poor metalurgy of low cost motors.