20 in Fat-Tire Electric Bike with 1000 W Rear Hub Motor
HKM-3417811 Electric Fat Bike
The HKM-3417811 is a 20 in fat-tire electric bike built for riders who want one machine for the weekday commute and the weekend gravel detour. A 1000 W brushless rear hub motor draws from a 48 V 20 Ah integrated lithium pack holding 960 Wh, which is good for 37-50 mi (60-80 km) between charges and a top speed of 31 mph (50 km/h). The 20 x 4.0 in fat tires flatten broken pavement, packed dirt, sand and light snow, while a 7-speed derailleur, disc brakes at both ends and a 71 lb (32 kg) aluminum alloy frame keep the bike manageable to ride, park and lift.
1000 W Brushless Rear Hub48 V 20 Ah / 960 Wh Pack31 mph Top Speed37-50 mi Range20 x 4.0 in Fat Tires7-Speed DrivetrainDisc Brakes Front and Rear275 lb Load Capacity
Motor
1000 W
Brushless rear hub drive
Battery
48 V 20 Ah
960 Wh integrated lithium
Top Speed
31 mph
50 km/h on level ground
Range
37-50 mi
60-80 km, varies with assist
Tires
20 x 4.0 in
Fat tread, pavement to gravel
Load Capacity
275 lb
125 kg rider plus cargo
Overview
The HKM-3417811 uses the 20 in fat-wheel format for a specific reason: the smaller diameter drops standover height and shortens the reach to the ground, while the 4.0 in casing restores the ride comfort and float that a small wheel would otherwise give up. The result is a bike that fits a wide range of riders, feels planted at low speed in city traffic, and still rolls confidently onto a canal path or a beach access track.
Propulsion comes from a 1000 W brushless motor laced into the rear wheel. There is no chain or belt between the motor and the ground, so drive losses stay low and there is nothing extra to service on the drive side. The motor pulls from a standstill without any pedal input, which is the single most useful characteristic on a bike this heavy when you are setting off from a red light with a loaded rack.
Energy comes from a 48 V 20 Ah lithium pack integrated into the down tube so nothing hangs off the frame. 960 Wh returns 37-50 mi (60-80 km) depending on how much you pedal, how much you carry and how cold it is. Throttle-only riding at higher speeds sits toward the lower figure; moderate pedal-assist on flat pavement reaches the upper one and, on a light day with low assist, can exceed it.
Chassis hardware matches the drivetrain rather than undercutting it. The frame is aluminum alloy, which keeps corrosion at bay through winter road film and holds the complete bike to 71 lb (32 kg). A 7-speed derailleur gives usable cadence from walking pace up to cruising speed, and mechanical disc brakes front and rear provide the stopping power a 31 mph bike carrying up to 275 lb (125 kg) actually needs.
Key Features
1000 W Brushless Rear Hub Motor
A 1000 W brushless motor is built directly into the rear wheel hub, so power reaches the ground without an intermediate chain or belt. Maintenance on the drive side reduces to keeping the axle nuts torqued and the connector clean. Output is sufficient for sustained climbing on grades approaching 30 degrees with a solo rider, and it pulls away from a standing start without any pedal input at all.
48 V 20 Ah Integrated Lithium Pack (960 Wh)
The pack is integrated into the down tube behind a lockable cover, which protects the cells from road spray and keeps the silhouette clean. 960 Wh covers a full week of short commutes between charges. A complete recharge from empty takes roughly 6-8 hours on the supplied smart charger, and partial top-ups take proportionally less. The pack lifts out on a key so it can be charged indoors.
Front Suspension Fork and 4.0 in Tire Compliance
A coil suspension fork with preload adjustment takes the sharp edge off kerbs, expansion joints and gravel. Behind it, the 4.0 in tire casing run at moderate pressure does the work a rear shock would do on a lighter bike, absorbing high-frequency chatter through the sheer volume of air in the tire. Riders who spend most of their time on smooth tarmac can wind preload up to firm the front end for efficiency.
Disc Brakes, Front and Rear
Discs at both ends give consistent stopping power in the wet, where rim brakes lose bite, and they clear mud and grit far better on unpaved surfaces. Power-off brake levers cut motor drive the instant either lever is pulled, which matters on a bike that can reach 31 mph. Pads are a standard size and are straightforward to replace.
7-Speed Derailleur Drivetrain
A 7-speed rear derailleur with an index shifter keeps pedal cadence usable across the full speed range instead of leaving you spinning out above 15 mph. The lower gears also let a heavier rider contribute real power on a climb rather than leaving the motor to carry the whole load, which is what protects range on hilly routes.
20 x 4.0 in All-Terrain Fat Tires
The wide casing spreads rider and cargo weight over a large contact patch. At 15-20 psi the tires roll efficiently on tarmac; dropped to 10-12 psi they flatten out and float over sand, packed snow and loose gravel where a 2 in tire would cut in and wash out. Tread is a multi-surface block pattern rather than an aggressive off-road knob, so road noise stays reasonable.
LED Headlight and Backlit LCD
A front LED headlight runs off the main pack, so there is no separate battery to keep charged, and a rear reflector plus brake-activated tail light add visibility from behind. The backlit LCD reports speed, state of charge, assist level, trip distance and odometer, and stays readable in daylight.
Rear Rack Platform and Cargo Mounts
The rear rack platform accepts panniers, a trunk bag or a strapped crate, and the frame carries standard bottle and accessory bosses. Between rack and frame mounts the bike absorbs a grocery run or a commuting load without the handling penalty of a backpack, all within the 275 lb (125 kg) total load rating.
Full Specifications
Model
HKM-3417811 | Electric Fat Bike
Frame Material
Aluminum alloy, 20 in fat-tire geometry
Motor
1000 W brushless rear hub motor
System Voltage
48 V DC
Battery
48 V 20 Ah lithium-ion (960 Wh), integrated and lockable
Charger
Smart charger with LED status, 100-240 V input
Charging Time
Approximately 6-8 hours from empty
Battery Cycle Life
Approximately 800 charge cycles to 80 percent capacity
Top Speed
31 mph (50 km/h)
Range Per Charge
37-50 mi (60-80 km), varies with terrain, rider weight, and assist level
Climbing Grade
Up to approximately 30 degrees with a solo rider
Assist System
5 pedal-assist levels plus zero assist, cadence sensing
Drivetrain
7-speed derailleur with index shifter
Brakes
Disc brakes front and rear, with power-off levers
Suspension
Coil front suspension fork with preload adjustment
Tires
20 x 4.0 in fat tires, multi-surface block tread
Wheels
20 in alloy rims, stainless steel spokes
Saddle
Wide padded saddle with quick-release seatpost clamp
Display
Backlit LCD: speed, battery level, assist mode, trip distance, odometer
Throttle
Twist-grip throttle, operates independently of assist level
Lighting
LED headlight and brake-activated tail light, powered by main battery
Load Capacity
275 lb (125 kg) rider plus cargo
Bike Weight
Approximately 71 lb (32 kg) including battery
Recommended Rider Height
5 ft 1 in to 6 ft 3 in (155-190 cm)
Certifications
CE, RoHS; battery cells UN38.3 tested
Battery, Range, and Charging
The 48 V 20 Ah pack stores 960 Wh. Typical commuter e-bikes ship with 400-600 Wh, so this pack carries roughly 60-140 percent more energy than the category norm. That headroom is what turns a stated 37-50 mi (60-80 km) figure into a bike you can ride all week on one charge rather than one you plug in every evening.
Four variables move real-world range more than anything else: how much you pedal, total load, tire pressure and temperature. Throttle-only riding near the 31 mph top speed lands around 37 mi. Moderate pedal-assist at 15-18 mph on flat pavement regularly returns the full 50 mi. Cold below 40 F (4 C) temporarily trims available capacity by 10-20 percent, and it comes back once the pack warms up. Soft tires on tarmac are the most common avoidable cause of lost range.
Tip: Store the pack between 30 and 70 percent charge if the bike will sit unused for more than a month, and top it up every 4-6 weeks. Charging indoors at room temperature rather than in an unheated garage measurably extends usable pack life.
The pack unlocks with the supplied key and lifts clear of the down tube in seconds, so it can charge at a desk while the bike stays locked outside. Two keys are included. Charging in place works equally well - the charge port is reachable from the drive side without removing anything.
Daily Use & Care
- Tire pressure sets the character of the bike. Run 15-20 psi on pavement for lower rolling resistance; drop to 10-12 psi for sand, gravel or packed snow so the casing can flatten and float.
- Rinse the frame, rims and drivetrain with fresh water after riding on salted roads. Road film attacks aluminum fasteners and the chain over a single winter if it is left in place.
- Check the rear axle nuts weekly. Hub-motor torque works axle hardware loose faster than on a conventional bicycle, and a moving axle will chew the dropouts.
- Wipe and re-lubricate the chain every 100-150 mi, and after any ride through standing water or heavy dust.
- Inspect brake pad thickness monthly and replace when the friction material drops below 1 mm. Disc pads wear quietly and give little warning.
- Charge indoors at room temperature and unplug once the charger indicator turns green rather than leaving it connected for days at a time.
- Keep the display boot and the charge port cover closed whenever the bike is parked outside so moisture stays out of the connectors.
What's in the Box
- 1 x HKM-3417811 electric fat bike, approximately 85 percent pre-assembled
- 1 x 48 V 20 Ah integrated lithium battery pack
- 1 x Smart charger with LED status indication, 100-240 V input
- 2 x Battery keys
- 1 x Toolkit with hex wrenches and pedal spanner
- 1 x Pair of pedals
- 1 x Front wheel hardware and reflector set
- 1 x User manual and assembly guide
Frequently Asked Questions
How much assembly is required out of the box?+
The bike ships approximately 85 percent assembled. Remaining steps are fitting the front wheel, straightening and bolting the handlebar, installing the pedals and saddle, and checking brake alignment. Budget 30-45 minutes with the supplied tools. If you are not comfortable setting brake calipers, have a bike shop check torque and pad alignment before the first ride.
What surfaces can the 4.0 in tires actually handle?+
Pavement, gravel paths, hardpack dirt, beach sand above the waterline and packed snow are all within the design envelope once pressure is set for the surface. Deep mud and technical rock are not - this is a fat-tire commuter and light-trail bike, not a full-suspension mountain bike.
What range should I plan for?+
Plan 37-50 mi (60-80 km). Throttle-only riding near the top speed lands close to 37 mi; moderate pedal-assist at 15-18 mph on flat pavement regularly returns the full 50 mi. Heavier riders, headwinds, hills, cargo and low tire pressure all reduce that figure.
Is a license or registration required?+
Rules vary by state and locality. A 1000 W motor with a 31 mph top speed exceeds the limits of the common three-class e-bike framework in many US jurisdictions, which may place this bike in a moped or motor-driven cycle category. Check your state DMV and local ordinances before riding on public roads or bike paths.
How long does the battery take to charge?+
Approximately 6-8 hours from fully empty on the supplied smart charger. Partial top-ups take proportionally less time, and there is no need to run the pack down before recharging - lithium cells prefer shallow cycles.
Can I pedal it if the battery runs out?+
Yes. The 7-speed derailleur drivetrain is fully independent of the motor. At 71 lb (32 kg) with fat tires the bike is slow going unassisted, but it is entirely rideable home on level ground.
Will the brakes cope with the speed and a loaded rack?+
Discs front and rear are the correct specification for a 31 mph bike at this weight. Bed the pads in over the first few rides with 10-15 progressive stops from moderate speed to build the friction layer on the rotors, and brake earlier than you would on an unloaded bike when the rack is full.
Is the battery removable for indoor charging?+
Yes. It unlocks with the supplied key and lifts out of the down tube. You can also charge it in place through the frame-side charge port if the bike is stored somewhere with an outlet.
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The product is covered by a 24-month warranty from the delivery date against manufacturing defects. Coverage includes parts and labor; normal-wear items are excluded.
CERoHSUN38.3 Battery960 Wh PackDisc Brakes7-SpeedAluminum Frame
Why Choose the HKM-3417811
One Bike for Commute and Weekend
The 20 in fat format is a genuine dual-purpose layout: narrow enough to thread traffic and park in a hallway, wide enough on the tire to leave the tarmac at the end of the street. You are not choosing between a city bike and a trail bike, and you are not maintaining two of them.
Fat Tires Instead of a Full Suspension Frame
Four inches of tire at 12 psi absorbs a remarkable amount of surface noise without the pivots, bearings and servicing a rear shock adds. With a coil fork up front for the sharp hits, the bike stays comfortable over broken pavement while keeping the frame simple and the weight down.
Throttle or Pedals, Your Choice
Twist the throttle for immediate motor-only acceleration, or shift through the 7-speed cassette and add your own power. Most owners use both - throttle to get moving from a stop, pedals to stretch range across the second half of a commute.
Hub Drive, Fewer Moving Parts
With the motor inside the rear wheel there is no mid-drive gearbox, no second chain and no belt in the power path. Fewer moving parts means less to wear out, less to adjust and a notably quiet ride at speed.
Low Standover, Wide Fit Range
The 20 in wheel diameter drops standover height so most riders between 5 ft 1 in and 6 ft 3 in can flat-foot the ground at a stop. Combined with a quick-release seatpost clamp, the bike adapts to different riders in a household in seconds.
Built for Year-Round Commuting
Sealed connectors, a covered and lockable battery compartment, discs that shrug off wet weather and an aluminum frame that will not rust through a salted winter all point at the same thing: a bike meant to be ridden every day and parked outside, not stored for the season.
Controls & Indicators
Power Button
On the display housing; hold to switch the system on and off
Assist Buttons
Up and down buttons cycle through 5 pedal-assist levels plus zero assist
Twist Throttle
Right-hand grip; proportional response, independent of the assist level
Speedometer
Live speed readout in mph, switchable to km/h in the settings menu
Battery Gauge
Segmented charge indicator plus voltage readout on the LCD
Light Switch
Long-press the up button to toggle the LED headlight and tail light
Shifter
Right-hand index shifter for the 7-speed rear derailleur
Pre-Ride Safety Checklist
- Check tire pressure and set it for the surface: 15-20 psi for pavement, 10-12 psi for sand, gravel or snow.
- Squeeze both brake levers. They should firm up well before touching the grip, with no travel that keeps increasing under steady pressure.
- Confirm the battery is seated and locked and that the display shows the expected state of charge.
- Spin both wheels and check that the rims run true and that nothing rubs the rotors or the frame.
- Verify the axle nuts and stem bolts are tight, and that the headset has no play when you rock the bike with the front brake applied.
- Shift through all 7 gears with the bike on a stand to confirm the derailleur indexes cleanly before you need a low gear on a hill.
- Test the throttle at walking pace in a clear area before riding in traffic, especially if the rack is loaded.
- Switch on the headlight and tail light for dusk riding, and wear a helmet rated for the 31 mph this bike can reach.
Quick Troubleshooting
The motor does not engage when I twist the throttle.+
Confirm the display is on and shows charge, the battery is locked into the down tube, and both brake levers are fully released - the brake cut-off sensors disable motor drive while a lever is pulled. If the display reports an error code, note it before contacting support.
Range dropped noticeably compared with when it was new.+
Check tire pressure first; a soft 4.0 in tire on pavement is by far the most common cause and can cost a fifth of your range. Then consider temperature, since cold reduces available capacity temporarily. If range is down more than 30 percent year-round after many charge cycles, the pack is approaching the end of its service life.
The brakes squeal or feel weak.+
Squeal is usually contamination on the pads or rotor - clean the rotor with isopropyl alcohol and de-glaze the pads. Weak braking on new pads normally means they have not been bedded in; perform 10-15 progressive stops from moderate speed. If a lever pulls to the grip, the caliper needs adjustment.
The chain skips under hard pedaling.+
Derailleur indexing is likely out of adjustment, or the chain and cassette are worn. Turn the barrel adjuster a quarter turn at a time until shifts land cleanly. If the chain only skips in the smallest cogs, the cassette is worn and should be replaced along with the chain.
The front fork clunks over bumps.+
Check that the front axle is fully seated and torqued and that the headset is not loose - a loose headset feels almost identical to a failing fork. If the noise persists, inspect the stanchions for scoring and have the fork serviced.
The display shows an error code and the bike will not move.+
Power the system off, wait 30 seconds and switch it back on. If the code returns, record the exact code and the conditions that produced it, then contact support - codes map to specific faults in the controller, motor, throttle or brake-sensor circuits.
Certifications & Standards
The HKM-3417811 is produced in a facility operating under an ISO 9001 quality management system. The battery cells and the assembled pack carry the test documentation normally required for lithium-ion transport and sale.
- CE - European Conformity marking covering the electrical assembly.
- RoHS - Restriction of Hazardous Substances compliance for the electronics.
- UN38.3 - Battery transport safety testing, required for lithium-ion shipping by air, sea, and road.
- MSDS - Material Safety Data Sheet available for the battery pack on request.
- ISO 9001 - Quality management system certification held by the manufacturing facility.
Important Safety Notes
This is a high-output electric bicycle capable of 31 mph (50 km/h) with a 1000 W motor. Read the manual fully before the first ride and practise throttle control in an open, traffic-free area until the response feels predictable. Braking distances lengthen noticeably once the rack is loaded or the surface is wet.
- Wear a helmet on every ride. At 31 mph a standard bicycle helmet is the minimum specification.
- Do not exceed the 275 lb (125 kg) load capacity, which includes the rider, clothing and all cargo.
- Check local law before riding on public roads or paths. A 1000 W motor with a 31 mph top speed may place this vehicle outside standard e-bike classifications in your area.
- Bed in the brake pads with 10-15 progressive stops during the first few rides before riding at full speed or with a loaded rack.
- Do not ride through water deep enough to reach the hub motor or the battery compartment.
- Charge only with the supplied charger, indoors, at room temperature, and on a non-flammable surface. Do not leave a charging battery unattended overnight.
- Do not attempt to open, puncture or modify the battery pack. Damaged lithium packs can vent and ignite.
- Reduce speed substantially on wet surfaces, loose gravel and downhill grades; fat tires add grip but do not eliminate the risk of losing traction.
HKM-3417811 · 1000 W brushless rear hub motor · 48 V 20 Ah integrated lithium (960 Wh) · 31 mph (50 km/h) top speed · 37-50 mi (60-80 km) range · 6-8 h charge · 20 x 4.0 in fat tires · 7-speed derailleur · disc brakes front and rear · coil suspension fork · aluminum alloy frame · 71 lb (32 kg) bike weight · 275 lb (125 kg) load capacity. Specifications are provided for reference; actual performance varies with rider weight, terrain, tire pressure, temperature, and riding style. Range figures are measured under moderate pedal-assist on level pavement. This page describes the product only and is not legal advice regarding vehicle classification - confirm local regulations before riding on public roads.
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