52 V 2000 W Electric Fat Bike
HKM-3678419 Fat-Tire Electric Bike
The HKM-3678419 is built around a 2000 W brushless rear hub motor (2400 W peak) and a 52 V 20 Ah lithium pack (1040 Wh), matched so the pack is never the limiting factor on a long day out. 26 x 4.0 in tires carry the bike over broken pavement, gravel shoulders, and packed trail without hunting for a clean line, and a hydraulic front suspension fork takes care of what the casing cannot absorb. Hydraulic disc brakes at both ends give repeatable stopping power, and the 7-speed derailleur adds usable cadence from walking pace up to cruising speed. A backlit display, integrated LED lighting, and an aluminum alloy frame rated for 330 lb round out a bike sized for daily use rather than an occasional weekend loop. Expect 37-50 mi (60-80 km) from a full charge depending on how much you pedal.
2000 W rear hub motor52 V 20 Ah / 1040 Wh Pack34 mph Top Speed37-50 mi Range26 x 4.0 in TiresHydraulic disc brakesFront suspension fork330 lb Load Capacity
Motor
2000 W
2400 W peak rear hub
Battery
52 V 20 Ah
1040 Wh removable lithium
Top Speed
34 mph
55 km/h
Range
37-50 mi
60-80 km, varies with assist
Tires
26 x 4.0 in
Multi-surface tread
Load Capacity
330 lb
150 kg rider plus cargo
Overview
The HKM-3678419 is a fat-tire electric bike built on an aluminum alloy frame. Aluminum keeps the weight manageable for a bike in this power class while resisting the road salt and wet weather a commuter bike sees every winter. The frame is rated for a combined rider-and-cargo load of 330 lb, and the bike itself weighs roughly 80 lb with the battery installed.
Power comes from a 2000 W brushless rear hub motor (2400 W peak). Nominal output is what the motor sustains; the peak figure is what it delivers in short bursts on a climb or pulling away from a stop. Rated torque is about 130 N.m, which is what makes the difference on a loaded start rather than raw wattage. The pack is a 52 V 20 Ah lithium pack (1040 Wh) and recharges in roughly 7-8 hours from empty.
Real-world range is a band, not a number. Throttle-only riding at the top of the speed range lands near the low end of 37-50 mi. Moderate pedal-assist on mixed terrain regularly reaches the middle of that band, and steady pedalling at the lowest assist level on flat ground is what produces the high figure. Cold weather below 40 F (4 C), soft tires, headwinds, and hills all pull the number down.
A hydraulic front fork with preload adjustment absorbs the hits that reach the front wheel, and most versions include a lockout so the fork can be firmed up for efficient pedalling on smooth pavement. The 26 x 4.0 in casings do a large share of the damping work on their own: dropped to 10-12 psi they flatten over roots and gravel in a way a narrow tire cannot.
Key Features
2000 W Brushless Rear Hub Motor
A 2000 W brushless motor (2400 W peak) is laced directly into the rear wheel. There is no belt or secondary chain in the drive path, so losses stay low and maintenance comes down to keeping the axle nuts torqued. Peak output is what pulls the bike away from a standing start on a grade with a loaded rack.
52 V 20 Ah Lithium Pack (1040 Wh)
The pack holds 1040 Wh, enough for 37-50 mi of mixed riding between charges. It locks into the frame and lifts out with a key so it can be charged at a desk while the bike stays locked outside. A full charge from empty takes about 7-8 hours; partial top-ups take proportionally less and do no harm to the cells.
Hydraulic Front Suspension Fork with Lockout
The fork damps the impacts that reach the front wheel and can be locked out when you are on smooth pavement and want the energy going into forward motion instead of into fork travel. Preload is adjustable at the crown so heavier and lighter riders can both get sensible sag.
Hydraulic disc brakes, Front and Rear
Sealed hydraulic lines actuate both calipers. Lever effort stays light and predictable when the rotors heat up on a long descent, and there is no cable to stretch or corrode. Motor cut-off switches in both levers drop drive the instant either lever moves.
7-Speed Derailleur Drivetrain
A 7-speed cassette with an index shifter gives usable cadence from walking pace up to the top of the assisted speed range. The gear spread is what lets a heavier rider hold a climb without stalling the motor, and what makes the bike rideable at all once the pack is empty.
26 x 4.0 in Tires
Run at low pressure the 26 x 4.0 in casing spreads rider and cargo weight across a wide contact patch, which is what gives a fat bike grip on gravel, wet leaves, packed sand, and light snow. On pavement, 15-20 psi keeps rolling resistance sensible; drop to 10-12 psi when the surface turns loose.
LED Headlight and Brake-Activated Tail-Light
Both lights run off the main pack, so there are no coin cells or USB lamps to keep charged. The tail-light brightens whenever either brake lever is pulled, which is the single most useful visibility feature in slow traffic and at dusk.
Rear Rack Mounts and Cargo Capacity
Threaded eyelets at the rear dropouts and seat stays take a standard rack, and the frame load rating of 330 lb leaves real headroom for panniers and a top bag once the rider is accounted for. Bottle-cage mounts sit inside the front triangle.
Full Specifications
Model
HKM-3678419 | Fat-Tire Electric Bike
Frame Material
Aluminum alloy, fat-tire hardtail geometry
Motor
2000 W brushless rear hub motor, 2400 W peak
System Voltage
52 V DC
Battery
52 V 20 Ah lithium-ion (1040 Wh), removable and lockable
Charger
Smart charger, 100-240 V input, auto cut-off
Charging Time
7-8 hours from empty
Battery Cycle Life
Approximately 800 charge cycles to 80 percent of rated capacity
Top Speed
34 mph (55 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
Peak Torque
130 N.m
Drivetrain
7-Speed derailleur with index shifter
Brakes
Hydraulic disc brakes, front and rear, with motor cut-off levers
Suspension
Hydraulic front fork with preload adjustment and lockout
Tires
26 x 4.0 in, knobby all-terrain tread
Wheels
26 in alloy rims, stainless spokes, sealed hub bearings
Saddle
Wide padded saddle with elastomer inserts, quick-release post
Display
Backlit LCD: speed, battery level, assist mode, trip distance, odometer
Throttle
Twist-grip throttle plus 5 pedal-assist levels and zero assist
Lighting
LED headlight and brake-activated tail-light, powered by the main pack
Load Capacity
330 lb (150 kg) rider plus cargo
Bike Weight
Approximately 80 lb (36 kg) including battery
Recommended Rider Height
5 ft 2 in to 6 ft 4 in (157-193 cm)
Certifications
CE, RoHS; battery cells UN38.3 tested
Battery, Range, and Charging
The 52 V 20 Ah pack stores 1040 Wh. For reference, a typical commuter e-bike ships with 400-600 Wh, so this one sits well above that band. Energy capacity, not motor wattage, is what decides whether the bike gets you home, and it is the single specification worth paying attention to when comparing models.
Four variables move real-world range more than anything else: how much you pedal, total loaded weight, tire pressure, and terrain. Throttle-heavy riding at the top of the speed range returns close to 37 mi. Moderate pedal-assist on rolling terrain sits mid-band. Steady pedalling at the lowest assist level on flat ground is what produces the 50 mi figure. Temperatures below 40 F (4 C) temporarily reduce available capacity by 10-20 percent; it comes back as the pack warms.
Tip: Store the pack between 30 and 70 percent charge if the bike will sit 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 out of the frame in a few 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 without removing anything, and the charger cuts off automatically when the pack is full, so a top-up left running while you eat lunch does no harm.
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 gravel, sand, and dirt so the casing can flatten and grip.
- Rinse the frame, rims, and drivetrain with fresh water after riding on salted roads or wet gravel. Road film attacks fasteners and bearing seals if it is left to dry in place.
- Check that the axle nuts, stem bolts, and rack fasteners are torqued before the first ride of each week. Motor torque works hardware loose faster than on a conventional bicycle.
- Wipe and re-lubricate the chain every 100-150 mi, or after any ride through standing water or heavy dust.
- Inspect brake pad thickness monthly. Hydraulic pads wear quietly until they are gone; replace when the friction material is under 1 mm.
- Charge indoors at room temperature and unplug once the indicator turns green rather than leaving the charger connected for days at a time.
- Keep the display cover and charge-port cap closed whenever the bike is parked outdoors so moisture stays out of the connectors.
What's in the Box
- 1 x HKM-3678419 fat-tire electric bike, approximately 85 percent pre-assembled
- 1 x 52 V 20 Ah removable lithium battery pack (1040 Wh)
- 1 x Smart charger with 100-240 V input
- 2 x Battery keys
- 1 x Toolkit with hex wrenches and pedal spanner
- 1 x Pair of alloy platform pedals
- 1 x Front LED headlight (pre-installed)
- 1 x User manual, assembly guide, and warranty card
Frequently Asked Questions
How much assembly is required out of the box?+
The bike ships approximately 85 percent assembled. What remains is 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 torquing the stem and axle hardware, have a bike shop check it before the first ride.
What range should I actually plan for?+
Plan for 37-50 mi (60-80 km). Throttle-heavy riding at the top of the speed range lands near 37 mi; moderate pedal-assist on mixed terrain sits mid-band; steady pedalling at low assist on flat ground produces the 50 mi figure. Rider weight, headwinds, hills, cold weather, and low tire pressure all reduce it.
How long does the battery take to charge?+
About 7-8 hours from fully empty with the supplied charger. Partial top-ups take proportionally less time, and there is no benefit to running the pack down before recharging - lithium cells prefer partial cycles.
Is the battery removable for indoor charging?+
Yes. It unlocks with the supplied key and lifts out of the frame, so you can charge it indoors while the bike stays locked outside. You can also charge it in place through the frame-side port.
Can I pedal it if the battery runs out?+
Yes. The 7-speed derailleur works independently of the motor. The bike weighs about 80 lb, so unassisted pedalling is slower than on a conventional bicycle, but it is entirely rideable home on flat ground.
Do I need a license or registration?+
Rules vary by state and locality. A 2000 W motor with a 34 mph top speed exceeds the limits of the common three-class e-bike framework in many US jurisdictions, which may place this vehicle in a moped or motor-driven cycle category with registration, license, or insurance requirements. Check your state DMV and local ordinances before riding on public roads or bike paths.
Will the brakes cope with the speed and the load?+
Hydraulic disc brakes front and rear are the appropriate specification for a 34 mph bike at this weight. Bed the pads in during 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 bicycle when the rack is full.
What size rider does it fit?+
The recommended range is 5 ft 2 in to 6 ft 4 in (157-193 cm). Saddle height covers most of that range; riders at either end should also check standover clearance, which is set by the 26 in wheel size and the frame geometry.
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CERoHSUN38.3 Battery1040 Wh PackHydraulic BrakesFront suspension fork330 lb Load
Why Choose the HKM-3678419
Power Held in Reserve
A 2000 W motor with 2400 W peak spends most of its life well below its limit. Running an oversized motor at part load keeps temperatures down, keeps the controller out of current limit, and leaves headroom for the day you are two-up on a hill with a headwind.
Surfaces Other Bikes Route Around
26 x 4.0 in tires and front suspension fork open up gravel rail-trails, forestry roads, canal towpaths, and beach access tracks. The wide casing floats instead of cutting in, which is the difference between riding a soft surface and pushing across it.
Two Ways to Ride
Twist the throttle for immediate, clutch-free acceleration, or select one of 5 pedal-assist levels and ride it like a bicycle. Most owners mix the two - throttle away from a stop, assist to hold speed, and pedals to stretch the pack on the way home.
Fewer Parts in the Drive Path
The motor lives inside the wheel hub with no gearbox, belt, or secondary chain to service. Fewer moving parts in the drive path means less to maintain, and the ride is quiet enough to hold a conversation alongside another rider.
Cheap to Run, Simple to Park
A full charge costs a few cents of electricity and covers 37-50 mi. There is no fuel, no oil change, no annual emissions test, and in most towns no parking fee - the bike locks to the same rack a conventional bicycle uses.
Built for Weather, Not Just Weekends
Sealed connectors, a covered charge port, a gasketed battery bay, and stainless hardware at the fasteners most exposed to road film. Ride it in the rain, rinse the salt off afterwards, and the electrical side stays out of the conversation.
Controls & Indicators
Power Button
On the battery pack; hold to switch the system on and off
Mode Buttons
Up and down keys on the display cycle through 5 pedal-assist levels plus zero assist
Twist Throttle
Right-hand grip; proportional response, independent of the selected assist level
Speedometer
Live speed readout in mph, switchable to km/h in the settings menu
Battery Gauge
5-segment charge indicator plus a percentage readout on the display
Light Switch
Long-press the up key to toggle the LED headlight and tail-light
Shifter
Right-hand index shifter for the 7-speed rear derailleur
Pre-Ride Safety Checklist
- Set tire pressure for the surface you plan to ride: 15-20 psi for pavement, 10-12 psi for gravel or dirt.
- Squeeze both brake levers. They should firm up well before reaching the grip, with none of the sponginess that indicates air in the hydraulic line.
- Confirm the battery is seated and locked and that the display shows the state of charge you expect.
- Spin both wheels and check that the rims run true and nothing rubs a pad or the frame.
- Check that the quick-release levers and axle nuts are tight and that the headset has no play when you rock the bike with the front brake applied.
- Test the assist at walking pace in a clear area before entering traffic, especially if you have changed the assist level or ridden a different bike recently.
- Switch on the headlight and tail-light for any ride near dusk, and wear a helmet rated for the speeds this bike reaches.
- If you are carrying cargo, load it low and centred and re-check braking distance on the first quiet stretch of road.
Quick Troubleshooting
The motor does not engage when I ask for assist.+
Confirm the display is on and shows charge, the battery is locked fully into place, and both brake levers are released - the cut-off switches disable drive while a lever is pulled. If the display shows an error code, note it before powering down and contact support.
Range has dropped noticeably compared with when it was new.+
Check tire pressure first; a soft tire on pavement is the most common cause by a wide margin. Then consider temperature, since cold reduces available capacity temporarily. If range is down more than 30 percent year-round after several hundred cycles, the pack is approaching the end of its service life.
The brakes feel spongy at the lever.+
Sponginess in a hydraulic system usually means air in the line or a fluid leak. Stop riding and have the system bled and inspected. Do not continue riding a 34 mph bike on brakes you are not sure of.
The chain skips under hard pedalling.+
Indexing is most 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 it skips only in the smallest cogs, the cassette is worn and should be replaced together with the chain.
The front fork rattles or dives over bumps.+
Check that the axle and the fork crown bolts are tight and that the wheel is fully seated in the dropouts. If the rattle persists, increase preload at the crown; if the fork dives through its travel under braking, it needs service.
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, write down the exact code and what you were doing when it appeared, then contact support - codes map to specific faults in the controller, motor, throttle, or brake-sensor circuits.
Certifications & Standards
The HKM-3678419 is produced in a facility operating under an ISO 9001 quality management system. The cells and the assembled pack carry the test documentation normally required for lithium-ion transport and retail sale, and copies are available on request.
- 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 an electric bicycle capable of 34 mph. Read the manual fully before the first ride and practise assist and brake control in an open, traffic-free area until the response feels predictable. Loaded braking distances are noticeably longer than they are on an unloaded bicycle.
- Wear a helmet on every ride. At 34 mph a bicycle helmet is the minimum; many riders choose a certified downhill or motorcycle helmet at these speeds.
- Do not exceed the 330 lb (150 kg) load capacity, which includes the rider and all cargo.
- Check local law before riding on public roads or paths. A 2000 W motor with a 34 mph top speed may fall outside standard e-bike classifications in your area.
- Bed the brake pads in 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 wheel hubs or the battery bay.
- Charge only with the supplied charger, indoors, at room temperature, on a non-flammable surface. Do not leave a charging pack unattended overnight.
- Do not open, puncture, or modify the battery pack. A damaged lithium pack can vent and ignite.
- Reduce speed substantially on gravel, wet surfaces, and downhill grades. Fat tires add grip but do not eliminate the risk of losing traction.
HKM-3678419 · 2000 W brushless rear hub (2400 W peak) · 52 V 20 Ah lithium (1040 Wh) · 34 mph top speed · 37-50 mi range · 26 x 4.0 in tires · 330 lb (150 kg) load capacity · aluminum alloy frame · front suspension fork · hydraulic disc brakes · 7-speed derailleur. 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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