A 2000W hub motor packed into a 20-inch fat wheel trades range for instant torque. The SHZICMY kit (Amazon) nails snow riding. It fights loose sand. You require a 48V battery to make it live.
What Comes in the Box
Motorized rear wheel with a sealed gearless hub. A controller box with a pre-wired harness. An LCD display on a reusable adhesive mount. A five-speed PAS sensor ring. A twist throttle. Wiring diagram sticker and manual. No battery in the box. You supply a 48V pack. A 48V 15Ah to 20Ah with a 30A to 40A BMS gives reasonable runtime. A smaller 10Ah pack works but sags fast under full throttle. The motorized wheel adds noticeable weight to the rear end. Expect stiffer spoke tension checks through the first 100 miles. Fat frames tolerate the shift better than lightweight aluminum singles.
Power, Speed, and the Small-Wheel Trade
The spec sheet claims 2000W peak and 34 mph top speed. That 34 mph is physically plausible. A 20-inch wheel spins faster than a 26, so the motor reaches high speed at lower RPM. The sine-wave controller smooths out torque delivery and keeps noise down. The seller claims under 55 dB. On a snow bike with knobby tires, you won't hear the motor anyway.
Realistic continuous output sits below the 2000W peak. Gearless hubs draw less current than geared versions but lack a freewheeling planetary set. The payoff is near-silent operation and less mechanical wear.
The 65 N·m torque figure lands in the middle of the 2000W kit pack. A 20x4 tire gives a wider contact patch than a standard 26x4.2, so you see less spin on hardpack and snow. On loose sand or wet mud, the small wheel diameter means the contact patch moves through terrain faster. You'll get more spin and a tendency to pop a wheelie at full throttle. Start at lower PAS levels until you understand the power curve. See this 2000W fat kit on Amazon if you want to compare specs side-by-side with other options.
The five PAS levels offer granular control. Level 1 barely nudges forward. Level 5 feels like a shove. Most riders live at levels 2 or 3. The pure electric mode gives full throttle without pedaling. It drains batteries fastest but delivers peak power when terrain demands it.
Cruise control activates after three seconds at a steady twist. Release the throttle and the motor holds speed automatically. Hills cause the controller to bump back to your PAS setting, interrupting cruise and feeling like a slight surge if you aren't watching.
Installation Notes
You swap the rear wheel. This is more work than a cassette change. You need 9mm or 12mm quick-release compatibility from your rear dropout. Most fat bike frames use 170mm or 177mm dropouts. This kit fits those. Measure your dropout spacing if your frame is non-standard.
Route the controller harness through internal cable channels if your frame has them. The wiring is longer than most budget kits. Secure all connections with zip ties. The LCD adhesive pad sticks well on flat bars but peels off on rounded ergonomic grips.
The PAS sensor ring needs crank magnet alignment. Install the bracket on the chainstay near the bottom bracket. Position the magnets on the crank arm. Rotate until the sensor gap sits 2 to 3 mm from the magnet. Test through full crank rotation. If the sensor misses, shift the ring a fraction and retest.
The throttle mounts opposite the PAS lever. If your bars are narrow, consider a bar-end mount. The LCD backlight makes reading in shade easy, though direct sunlight washes it out somewhat. Angle the display or add a simple sun visor for bright riding. Torque arms are mandatory. High torque on a short wheelbase demands a rear dropout anchor. This 2000W conversion kit's peak will spin the wheel inside the dropout without one. Thin dropout walls on budget frames are especially vulnerable. Buy an aftermarket torque arm. They are cheap and non-negotiable on this build.
The wiring harness plugs into the motor phases, throttle, PAS sensor, brake cut-offs, and your battery output. Match every connector before plugging in. Reverse polarity on the battery input kills the controller instantly.
Who Is This Kit For?
This kit targets fat bike owners or 20x4 frame builders focused on snow and sand. The design points squarely at hard snow surfaces. If you ride frozen marshes or coastal dunes, this motor punches above its weight.
Fat bike hunters benefit from instant torque at standstill and PAS-assisted pedaling through deep snow where throttle-only spins the wheel uselessly. The quiet sine-wave controller won't startle game.
Budget builders looking for a hackable platform get serious power for the money. Pair the kit with a used 48V LiFePO4 pack and mount the display on a flat bar. Grab this conversion kit on Amazon and check our full e-bike conversion kits directory for builds that target different wheel sizes or power classes.
Skip this kit if you want street-legal 750W power on a 26-inch wheel or you are building a lightweight commuter. The 20-inch wheel feels twitchy on pavement at higher speeds. Rear weight makes low-speed maneuvering harder, especially on tight singletrack. Check our blog for more build guides.
The SHZICMY kit holds 5.0 stars from four reviews. That sample is thin. The rating will shift as buyers accumulate real-world miles. Factor that uncertainty into your decision.
Frequently Asked Questions
Is the battery included with this kit?
No. You supply your own 48V battery pack. The kit includes the motorized wheel, controller, LCD display, PAS sensor, and throttle only. A 48V 15Ah to 20Ah pack with a 30A to 40A BMS is the recommended size.
Can this motor really hit 34 mph on a 20-inch wheel?
The claim is physically plausible on flat pavement. A 20-inch wheel spins faster than larger wheels, so the motor reaches that speed at lower RPM than a 26-inch build. Real top speed depends on rider weight, tire pressure, terrain, and your battery BMS limit. Expect slightly lower figures with a full-size adult in normal conditions.
Will this fit my 20x4 fat bike frame?
The kit targets 20x4 inch fat bike rear dropouts. Most fat bike frames use 170mm or 177mm spacing, which this wheel fits. If your frame has non-standard dropouts, verify the exact width before ordering.
Is the kit waterproof?
The motor hub handles light rain and trail spray. The LCD resists moisture too. Neither component is designed for full submersion or high-pressure hose-downs. Avoid deep puddles, direct pressure washing, or standing water deeper than a few inches. Wipe the LCD and controller after wet rides.
Can I use pedal assist or throttle only?
Both. PAS mode gives five assist levels from barely nudging to full power. Pure electric mode bypasses the PAS entirely and goes straight to throttle. Default operation is either-or.
How does the cruise control work?
Twist the throttle to your desired speed and hold for three seconds. The display flashes to confirm cruise is active. Release the throttle and the motor holds that speed automatically. Hitting the brakes or engaging PAS cancels cruise control.