In exchange for reduced travel distance, a 2000W hub motor installed in a 20-inch fat wheel provides instant torque. The SHZICMY kit (Amazon) is great for snow riding. It also helps fight against loose sand. A 48v battery is needed to run it.
What does the package include
An electrically powered rear wheel with a sealed gearless hub. A controller with a pre-assembled harness. A rechargeable display mounted on a reusable adhesive strip. A PAS sensor ring with five speed settings. A twist throttle. Sticker for a wiring diagram. Owner's manual. Battery not included. 48v battery required. A 48V 15Ah to 20Ah with a 30A to 40A BMS should give good runtime. However, a 10Ah battery will sag quickly while being run wide open. The added weight to the rear end due to the addition of the motorized wheel is notable. Expect tighter spoke tensions during the initial hundred miles of riding. Fat frames can handle the additional weight better than thin lightweight aluminum singles.
Power, speed, and the trade off between wheel size
The data sheet lists the 2000W motor peak and 34 mph top speed. Thirty-four miles per hour is physically possible. A twenty-inch wheel rotates much faster than a twenty-six inch wheel so the motor gets up to high speed sooner at a given RPM. The sine wave controller reduces the "torque ripple" associated with dc motors, thus reducing both audible noise and mechanical stress.
Seller claims under fifty-five decibels, however you probably wont even be able to hear the motor on your snow bike with knobby tires.
Practical continuous output will likely be lower than peak output. however, gearless hubs consume less current than their geared counterparts yet they do not have a freewheeling planetary set. Advantageously this results in silent operation and less mechanical wear.
The sixty-five newton-meter torque figure places this motor roughly in the middle of the 2000W kit group. The twenty by four tire will provide a greater contact area than the typical twenty six by four point two tire providing less spin on hardpack and snow. On soft sand or wet mud, the shorter wheel base will result in the contact patch moving through the terrain faster. This will cause more spin and potentially cause the wheel to pop into the air when running at full throttle. Start at lower PAS settings until you become familiar with the motor's Power curve. Click here to view specifications for this 2000W fat kit on Amazon for comparison with other models.
The five PAS settings allow for very fine control over how much assistance is provided. Level one produces nearly no forward motion. At level five you feel as if someone is pushing you along. Most users find themselves using level two or three. Pure electric mode allows maximum throttle without pedalling. This will drain the batteries at the highest rate but will deliver maximum Power when terrain requires it.
Cruise control activates after three seconds of maintaining constant throttle position. Release the throttle and the motor maintains your speed automatically. When going downhill, the controller will momentarily switch to your chosen PAS setting causing the motor to briefly apply some braking effect before returning to your previous throttle position and continuing to maintain speed.
Installation instructions
Installation involves swapping the rear wheel. Swapping the rear wheel is more difficult than changing cassettes. Your frame must have a compatible rear dropout configuration for 9mm or 12mm quick release. Most fat bikes have either 170mm or 177mm dropouts. Make sure to measure your dropout spacing if your frame does not conform to these standards.
Route the controller harness through any available internal cable routes in your frame. The wiring on this kit is longer than many budget kits. Secure all electrical connections with zip ties.
Position the PAS sensor ring near your chainstays (near the bottom bracket). Align the magnets attached to your crank arm and test for proper rotation through full crank stroke. If the sensor fails to register properly, move the ring slightly and re-test.
Mount the throttle opposite the PAS lever. If your bars are relatively narrow, consider mounting it on a bar-end. The backlight on the display will help read in shaded areas, but it will wash out significantly in direct sunlight. Mount it at an angle or install a simple sun shield for bright riding.
Torque arms are required. High torque on a short wheelbase demands attachment of a rear dropout anchor. See the SHZICMY kit listing on Amazon.
Failure to attach one will result in failure of the wheel to remain within its dropout when subjected to peak load such as when hitting a berm or cornering aggressively. While torque arms are inexpensive, failure to install one may compromise safety of both yourself and others around you.
The wiring harness connects to phases of motor, throttle, PAS sensor, brake cut-off and your battery's output connectors. Connect each connector correctly before plugging-in.
Reverse polarity on your battery input will kill the controller immediately upon connection.
Who would benefit from this kit?
This kit is specifically intended for fat bike enthusiasts or builders of frames with a twenty by four inch tire who intend to focus primarily on riding on snow and/or sand. Design goals clearly include riding on hard snowy surfaces. If you plan on riding in marshy or sandy areas (i.e., coastal dune riding), this motor packs a punch above its weight class.
Users of fat bikes that need instant torque at a dead stop and then assistance via PAS through deep snow where throttling alone would cause excessive spinning, greatly appreciate this feature.
Hunters using fat bikes enjoy having instant torque at a dead stop and assistance via PAS through deep snow where throttling alone causes excessive spinning. Hunters also appreciate that the sine-wave controller eliminates any startling effects when hunting.
Economical builders who desire an easily modifiable platform receive substantial Power relative to price. Pair this kit with a previously owned forty-eight volt lithium iron phosphate battery package and mount the display on a flat bar. You can obtain this conversion kit on Amazon as well as browse our complete e-bike conversion kits directory for builds that emphasize different wheel diameters or varying degrees of Power.
Avoid purchasing this kit if you're seeking legal street-riding capability at seventy-five watts on a twenty-six inch wheel or you are creating an economical commuting vehicle that emphasizes low weight and minimal drag resistance. The twenty-inch wheel exhibits instability at increased speeds on pavement. Low-speed maneuverability becomes more difficult due to excess weight added at the rear of the bike, particularly in tight single-track sections.
Click here to visit our blog for other build guides.
SHZICMY kit has received 5 star ratings from four reviewers currently listed online. The sample size is very small at this time. As buyers acquire actual mileage experience, we anticipate changes in user feedback ratings.
Commonly asked questions
Does this kit come with a battery?
No. You must provide your own 48v battery pack. The kit contains everything else except the battery including: an electrically powered rear wheel with a sealed gearless hub. controller unit with a pre-wired harness. rechargeable display mounted on a reusable adhesive strip. five-speed PAS sensor ring. twist throttle. sticker for wiring diagram. owner's manual. etc..
Can this motor truly achieve thirty-four miles per hour on a twenty-inch wheel?
We believe it is physically possible to reach thirty-four miles-per-hour on flat ground based on this information regarding wheel diameter and RPM relationship (the motor achieves higher RPM at lower speeds). We know that in practical terms, actual top speed will depend upon numerous factors including rider weight, tire pressure, terrain and limitations imposed by your battery management system (BMS).
Will this kit fit my twenty-four inch fat bike frame?
This kit was designed to work with twenty by four inch fat bike rear dropouts (most fat bikes utilize either seventeen-zero-millimeter or seventeen-seven millimeter spaced dropouts). If your frame features non-standard dropout spacing, please verify dimensions prior to purchase.
Is this kit waterproof?
The motor hub withstands light precipitation and trail spray. The LCD screen resists moisture as well. None of these components were designed to be submerged in water nor endure high-pressure cleaning operations. Avoid riding through deep puddles, applying direct forceful water sprays, nor exposing the LCD/controller to standing water exceeding several inches.
May i operate solely in pedal assist or throttle only modes?
Yes. Using pedal assist mode allows selection among five assist levels ranging from very little propulsion to full Power. Pure electric mode bypasses pedal assist altogether allowing direct access to throttle only operation.
How does cruise control work?
When operating cruise control, hold the throttle at your desired speed for three seconds, displaying flash confirmation on the LCD screen that indicates cruise is now activated. Release throttle and cruise will continue holding your selected speed automatically. Releasing brakes or engaging pedal assist will cancel cruise control mode.
See the full kit listing on Amazon for current component availability, then compare against other builds in the conversion kit comparison table.
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.
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