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GMAC Rear Barebones Kit

Rear GMAC Motor Kit, Throttle Only System without a Display or PAS/Torque Sensors. Powerful High Torque Geared Hub Motor without Clutch for Regen

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From USD$748.00

To USD$2,884.50 Regular Price USD$3,059.50

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SKU
KIT-GMAC_Bare
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Customize GMAC Rear Barebones Kit

The GMAC motors are available in 2 different winding speeds (fast and standard) depending on how fast you need to go for a given wheel diameter and battery voltage. In most scenarios, we recommend the fast wind for 20" wheels and the standard winding speed for 26" and larger.

The included splined torque arm fits inside the dropout and fully secures the axle against both forward and reverse torque from regen. 

GMAC Clutchless Geared Hub Motor, Standard 10T (8.1 rpm/V) Winding.

GMAC Clutchless Geared Hub Motor, Standard 10T (8.1 rpm/V) Winding.

GMAC Torque Arm Kit - SS

Laser-cut Stainless Steel Splined torque arm hardware assembly designed specifically for our GMAC motors.

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Laser-cut Stainless Steel Splined torque arm hardware assembly designed specifically for our GMAC motors.

Click Here for detailed product info page

You can get a bare hub and lace it into a suitable 36 hole rim yourself, or choose to get a professional wheel build done here at Grin using our stock rim selections and quality Sapim butted spokes.  Our head wheel builder Robert has decades of experience and is renowned for building wheels that are nearly bombproof. 

If you want Grin to do the wheelbuild, be sure to select either the Silver or Black spoke option from the dropdown menu, along with your preferred rim. By default all wheels will be be dished with the rim dead center between the dropouts, if you require some special dishing offset for an oddball frame please mention that in the order comments. If you are doing your own wheel build into your own rim and just require the spokes only, be sure to specify the required spoke length in the order comments to match your selected rim ERD and lacing pattern.

The Baserunner controller is ideal if you are getting a downtube battery as we will mount it inside the battery cradle.  The larger Phaserunner is required if you need an option that can run up to 72V, or if you are using one of the other battery models. It will also produce slightly higher peak torque due to the 90A vs 80A max phase current. 

New Model V6 Baserunner_L10 Field Oriented Motor Controller. Flat Profile Fits Many Downtube Battery Enclosures. L1019 Motor Plug. 80A Peak Phase Currents (~45-50A Continuous), for 24-52V Batteries (60V Max Input).   

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New Model V6 Baserunner_L10 Field Oriented Motor Controller. Flat Profile Fits Many Downtube Battery Enclosures. L1019 Motor Plug. 80A Peak Phase Currents (~45-50A Continuous), for 24-52V Batteries (60V Max Input).   

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Aluminum Controller Mount for Reention Poly-DPxC Series Downtube Batteries, Machined to fit Baserunner Motor Controllers

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Aluminum Controller Mount for Reention Poly-DPxC Series Downtube Batteries, Machined to fit Baserunner Motor Controllers

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Throttles, ebrake levers, pas sensors, and torque sensors all play a roll in how you interact with the ebike. Torque and PAS sensor automatically power the bike whenever you pedal with an assist level controlled by the CA3's MFSwitch, while a throttle gives manual control. Please see our PAS info page for more details on these options

Even if you choose a PAS or Torque sensor as the primary control, we always recommend having a throttle as well. It can be handy to accelerate in tight situations and is great as a back-up if ever the pedal sensor has issues.  

Regenerative Braking can be controlled with the addition of an ebrake lever, using the throttle to modulate the signal, or it can also be activated through back-pedal crank's rotation. 

Half Twist Throttle with Integrated On/Off Power Switch and Voltage Indicator. Connects to Main9 Connector of Baserunner or Phaserunner Controllers for Systems with No Cycle Analyst or Display. 115cm Cable Length for Main9 Connector

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Half Twist Throttle with Integrated On/Off Power Switch and Voltage Indicator. Connects to Main9 Connector of Baserunner or Phaserunner Controllers for Systems with No Cycle Analyst or Display. 115cm Cable Length for Main9 Connector

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The kit will run with any battery pack from 24V to 52V nominal (and up to 72V with a Phaserunner).
We offer a range of batteries that will work well depending on the geometry of your bike, the range you need on a charge, and how fast you want to go.  Please see our battery info page for more details on the different pack options.  
Be sure to select a charger model that matches the voltage (36V, 48V, or 52V) and connector style (ST3 or XLR) of the chosen pack.  

There are a number of optional electronic and mechanical accessories that can help flush out the build. This includes front and rear bike lights, phone chargers, wire management, programming cables, and what have you. 

Handlebar Phone Mount with both Wireless and USB Charging, Wide 12-95V Input Range.  

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Bike tracker that works with Apple Find My  

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Wide Voltage Range (6-60V), 3 watt Ebikes Light, Fork Fender mounting. 50cm cable, 5.5x2.1mm DC Jack. On/off Switch, Powers off Cycle Analyst/Anderson Tap. StVZO Compliant.

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Grin 12 LED Front E-Light, 72V Ready

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Super Bright (Max 1900 Lumen) Ebike Light with Handlebar Button and Hi/Low Beam Modes and Daytime Run Lights as Well. 12-60V Input Range with Reflective Cutoff Optics. Plugs Directly to Cycle Analyst.

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Main9 to DC 5.5mm x 2.1mm Male Adapter, 1m long. Provides Convenient Power Source for Rear Bike Lights from Unused Main9 Plug in Controllers with V3 Cycle Analyst  

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180cm DC Accessory Extension Cable

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Rear Ebike Light, No On/Off Push Button, 6-60V Input Range with DC 5.5x2.1mm DC Jack. 

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Parallel Anderson Cable for Baserunners Installed in Reention Case. Simplifies Dual Controllers or Dual Battery Systems.  Must be purchased with Baserunner and Reention battery

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4 Pieces of Snap Together Black Plastic Cable Raceway, 15 and 20mm Wide, 50cm long. Self Adhesive Tap Bonds to Bicycle Tube, Perfect for Hiding Cable Runs. 

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Cable Bundling Kit, includes Spiral Wrap, Zip Ties, and Velcro Sleeves

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Laser Engrave 250 Watt Continuous Power Rating on Motor Side Plate.  This is Truthfull. ALL Hub Motors Offered by Grin Have an Operating Point (RPM and Allowable Temperature) Where They Can Only Sustain 250W. 

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3m Long TTL-> USB programming cable for Satiator, Baserunner, Phaserunner and Cycle Analyst. *Note: All kits come pre-programmed, and most system behaviour is configurable with the Cycle Analyst buttons. But this cable is necessary if you plan to change more advanced controller settings or update device firmware* Full Product Info

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Schwalbe Big Apple 26" x 2.15 Puncture Resistant Tire. 

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GMAC Edge View
GMAC Rear Barebones Kit

In stock

USD$773.00

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Actual cruising speed/perfomance under any loading conditions is well modeled in our simulator.
Launch Motor Simulator with GMAC Rear Barebones Kit

Summary
  • Motor Winding Option:
    1 x GMAC 10T
  • GMAC Torque Arm:
    1 x GMAC Torque Arm Kit - SS
  • L10 Controller:
    1 x V6 Baserunner_L10 ETA: Apr 4 2025 (backordered)
  • Baserunner Controller Mount:
    1 x Reention battery baseplate, machined to fit Baserunner
  • All-in-one Throttle Style:
    1 x All-In-One Half Twist Throttle with Voltage LED (115cm Cable)

GMAC rear hub motor kit with optional battery pack and your choice of a Baserunner or Phaserunner motor controller.  If a Baserunner controller is selected along with a downtube battery pack, we will mount the controller inside the battery cradle for a very clean instal.

The GMAC motor has a 5:1 gear ratio and no internal clutch, allowing for regenerative braking capabilities that are not typically available with geared hub motors. Features 0.27m laminations, an integrated splined torque arm, and a Shimano HG compatible freehub system. Motor OLD is 138mm and fits in most bikes with slotted dropouts. 

The barebones system uses a throttle with an integrated on/off switch and voltage readout that is compatible up to 72V, but doesn't have a proper display or options for PAS / Torque sensors. This makes it great for simple and clean ebike builds that want to avoid any additional complexity.

The throttle also includes two extra wires for running a front bike light and hooking up an ebrake sensor.  The ebrake levers provide a fixed level of regenerative braking which is OK, but not quite as nice as the varying proportional regen that is possible with a V3 Cycle Analyst.