Aluminum-Frame 20 in Fat Tire Electric Bike
HKM-6563539 Electric Fat Tire Bike
The HKM-6563539 is a 20 in fat-tire electric bike built on a lightweight aluminum alloy frame, driven by a 750 W high-speed brushless motor laced into the rear hub. A 48 V 15 Ah lithium pack sits inside the down tube, so the silhouette stays clean and the weight stays low and centred. Twenty-inch off-road inflatable tires, a 7-speed derailleur, and a double disc brake set-up let the same bike handle a downtown commute in the morning and a gravel trail in the afternoon, and an IP45 water-resistance rating means a rain shower does not end the ride.
750 W (1000 W Peak) Motor48 V 15 Ah / 720 Wh Pack31 mph Top Speed20 x 4.0 in Off-Road TiresDouble Disc Brakes7-Speed DrivetrainIP45 Water Resistance309 lb Load Capacity
Motor
750 W
1000 W peak rear hub
Battery
48 V 15 Ah
720 Wh down-tube lithium
Top Speed
31 mph
50 km/h, throttle only
Range
22-31 mi
35-50 km per charge
Tires
20 x 4.0 in
Off-road inflatable fat tread
Load Capacity
309 lb
140 kg rider plus cargo
Overview
The HKM-6563539 starts with a lightweight aluminum alloy frame. Aluminum keeps the bike easy to lift onto a rack or carry up a short flight of steps, and it does not rust the way a painted steel frame will after a winter of salted roads. The geometry is deliberately neutral - upright enough for city traffic, long enough in the wheelbase to stay settled on loose gravel - which is what makes the bike approachable for a first-time electric rider and still satisfying for someone who already rides.
Power comes from a 750 W high-speed brushless motor built into the rear wheel hub, with roughly 1000 W available in short peaks for pulling away from a stop or holding speed on a climb. The battery is a 48 V 15 Ah lithium pack - about 720 Wh - carried inside the down tube rather than bolted on top of it. That placement lowers the centre of gravity, protects the cells from road spray, and leaves the rear rack area free for cargo.
Expect 22-31 mi (35-50 km) from a full charge. The lower end of that band is throttle-heavy riding at or near the 31 mph (50 km/h) top speed; the upper end is moderate pedal-assist on flatter ground with correctly inflated tires. Rider weight, headwind, ambient temperature, and how much you use the throttle all move the number, so treat 25 mi as a comfortable planning figure for a mixed-terrain day.
The 20 x 4.0 in off-road inflatable tires are the other half of the story. A tall, wide casing run at moderate pressure smooths out expansion joints and washboard gravel before the frame ever feels them, and the open tread pattern digs into dirt, wet leaves, and packed snow. Combined with the double disc brake system and the IP45 sealing on the electrical components, the bike is built to be used year-round rather than parked from November to March.
Key Features
750 W High-Speed Brushless Rear Hub Motor
The motor is laced directly into the rear wheel, so there is no chain or belt in the electric drive path and almost nothing to service. Nominal output is 750 W with roughly 1000 W available in short bursts, which is enough to hold speed on a moderate rise with a solo rider and to accelerate cleanly away from a green light without pedalling.
48 V 15 Ah Lithium Pack (720 Wh) in the Down Tube
The cells live inside the down tube behind a lockable cover, which keeps the frame lines clean and shields the pack from road spray and kerb strikes. Lift it out with the key to charge indoors, or plug into the frame-side port and leave it in place. A full charge from empty takes about 7-8 hours on the supplied 2 A charger.
Suspension Fork with High-Volume Tire Cushioning
A telescopic front fork takes the sting out of kerbs, potholes, and root-crossed trail sections, while the 4.0 in tires act as a second stage of suspension when you drop pressure for softer ground. The combination is what lets a 20 in wheel roll across broken pavement without transmitting every edge into your wrists.
Double Disc Braking System, Front and Rear
Discs on both wheels give consistent stopping force in rain, mud, and dust, where a rim brake would smear and fade. Independent front and rear circuits mean a single cable or caliper problem never leaves you without brakes, and motor cut-off switches in both levers kill drive the instant you reach for either one.
7-Speed Derailleur Gear System
Seven ratios cover everything from a low crawling gear for a steep gravel pitch to a tall gear that still lets you contribute at cruising speed. Index shifting from the right-hand grip is quick and repeatable, and pedalling in the correct gear noticeably extends how far the 720 Wh pack will take you.
20 x 4.0 in Off-Road Inflatable Fat Tires
The wide casing spreads load over a large contact patch, which is why the bike is rated to carry up to 140 kg without the tires squirming. Run higher pressure for low rolling resistance on tarmac; drop it for gravel, sand, and snow so the tread can flatten out and find grip.
LED Headlight and Brake-Activated Tail-Light
Both lights run off the main pack, so there are no coin cells or USB lamps to remember. The tail-light brightens whenever either brake lever is squeezed, which is the single most useful visibility feature on a bike ridden home in winter dusk.
Rear Rack, Mudguards, and Everyday Carrying
A bolt-on rear rack and full-length mudguards are fitted from the factory, so panniers, a top box, or a bungee-strapped crate go on without extra hardware. Within the 309 lb total rating there is comfortable headroom for a week of groceries or a loaded commuting bag on top of an adult rider.
Full Specifications
Model
HKM-6563539 | Electric Fat Tire Bike
Frame Material
Lightweight aluminum alloy, 20 in fat-tire geometry
Motor
750 W high-speed brushless rear hub motor, 1000 W peak
System Voltage
48 V DC
Battery
48 V 15 Ah lithium-ion (720 Wh), down-tube mounted, removable and lockable
Charger
2 A smart charger, 100-240 V input
Charging Time
7-8 hours from empty
Battery Cycle Life
Approximately 800 charge cycles to 80 percent capacity
Top Speed
31 mph (50 km/h)
Range Per Charge
22-31 mi (35-50 km), varies with terrain, rider weight, and assist level
Climbing Grade
Up to approximately 25 degrees with a solo rider
Peak Torque
65 N.m
Drivetrain
7-speed derailleur with index shifter
Brakes
Double disc brake system, front and rear, with motor cut-off levers
Suspension
Telescopic front suspension fork; high-volume tires add rear compliance
Tires
20 x 4.0 in off-road inflatable fat tires
Wheels
20 in alloy rims, stainless spokes
Saddle
Padded sport-comfort saddle with quick-release seatpost clamp
Display
Backlit LCD: speed, battery level, assist mode, trip distance, odometer
Throttle
Twist-grip throttle plus multi-level pedal assist
Lighting
LED headlight and brake-activated tail-light, powered by the main battery
Load Capacity
309 lb (140 kg) rider plus cargo
Bike Weight
Approximately 66 lb (30 kg) including battery
Recommended Rider Height
5 ft 2 in to 6 ft 3 in (157-190 cm)
Certifications
CE, RoHS; IP45 water resistance; battery cells UN38.3 tested
Battery, Range, and Charging
The 48 V 15 Ah pack holds roughly 720 Wh. It is carried inside the down tube rather than clamped to the outside of it, which keeps mass low in the frame and shields the cells from stones and spray thrown up by the front tire. A 10 Ah pack is offered on some builds of this platform; the figures on this page describe the 15 Ah configuration.
Range lands between 22 and 31 mi (35-50 km). Riding mostly on the throttle at or near 31 mph puts you at the bottom of that band. Moderate pedal-assist on flatter ground with tires inflated to the higher end of their range puts you at the top. Cold weather below 40 F (4 C) temporarily trims 10-20 percent of available capacity, which returns once the pack warms back up indoors.
Tip: If the bike will sit unused for more than a month, store the pack at roughly 30-70 percent charge and top it up every 4-6 weeks. Charging indoors at room temperature does more for long-term pack health than any other single habit.
The pack unlocks with the supplied key and slides out of the down tube in seconds, so it can charge on a desk while the bike stays locked in a bike room or on a balcony. Charging in place works exactly as well - the port sits on the drive side of the frame and stays accessible without removing anything.
Daily Use & Care
- Set tire pressure for the surface: run toward the upper end of the sidewall range on tarmac for lower rolling resistance, and drop pressure noticeably for gravel, sand, or snow so the tread can flatten and grip.
- Rinse the frame, rims, and drivetrain with fresh water after riding on salted roads or wet gravel. Aluminum resists rust, but road film still attacks fasteners and the chain.
- Check that both axle nuts and the stem bolts are torqued before the first ride of each week. Hub-motor torque loosens fasteners 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 disc pad thickness monthly and replace when the friction material is under 1 mm. Check that both rotors run straight through the caliper.
- Charge indoors at room temperature and unplug once the charger indicator turns green rather than leaving it connected for days.
- The IP45 rating covers rain and spray, not immersion. Keep the charge port cover closed when the bike is parked outside, and never pressure-wash the hub or battery compartment.
What's in the Box
- 1 x HKM-6563539 electric fat tire bike, approximately 85 percent pre-assembled
- 1 x 48 V 15 Ah removable lithium battery pack
- 1 x 2 A smart charger with 100-240 V input
- 2 x Battery keys
- 1 x Toolkit with hex wrenches and pedal spanner
- 1 x Pair of pedals
- 1 x Rear rack and mudguard set (pre-installed)
- 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. What remains is fitting the front wheel, aligning and bolting the handlebar, installing the pedals and saddle, and checking brake and gear alignment. Budget 30-45 minutes with the supplied tools. If you are not confident checking torque and brake bedding, have a bike shop do the final safety check.
Which battery capacity does this listing cover?+
This page describes the 48 V 15 Ah build, which stores about 720 Wh and returns 22-31 mi per charge. A 10 Ah version of the same platform exists; it uses identical hardware elsewhere but delivers proportionally less range.
What is the actual range I should plan for?+
Plan for 22-31 mi (35-50 km). Throttle-only riding near the 31 mph top speed lands close to 22 mi. Moderate pedal-assist on level ground with firm tires regularly reaches 31 mi. Heavier riders, headwinds, hills, cold weather, and soft tires all reduce range.
Is a license or registration required?+
Rules vary by state and locality. A 750 W nominal 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?+
About 7-8 hours from fully empty with the supplied 2 A charger. Partial top-ups take proportionally less time, and there is no need to run the pack flat before recharging.
Can I ride it in the rain?+
Yes, within reason. The electrical system carries an IP45 rating, which covers rain and road spray from any direction. It does not cover immersion, so avoid riding through standing water deep enough to reach the hub motor, and do not pressure-wash the bike.
Can I pedal it if the battery runs out?+
Yes. The 7-speed derailleur drivetrain works independently of the motor. At roughly 66 lb the bike is heavier than an ordinary bicycle, so unassisted pedalling is slow on hills, but it is entirely workable on flat ground.
How much weight can it carry?+
The rated capacity is 309 lb (140 kg), which includes the rider and everything on the rack. The wide tires and reinforced spoke pattern are the main reasons that figure is as high as it is.
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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 BatteryIP45 Rated720 Wh PackDouble Disc BrakesAluminum Frame
Why Choose the HKM-6563539
One Bike for Streets and Trails
The combination of a 7-speed drivetrain, a 750 W hub motor, and 4.0 in off-road tires means you do not have to choose between a commuter and a trail bike. The same machine handles a bike-lane sprint, a canal towpath, and a fire road without swapping tires or gearing.
Aluminum Alloy, Not Painted Steel
An aluminum frame keeps the total weight near 66 lb, which matters every time you lift the bike onto a rack or manoeuvre it through a doorway. It also shrugs off the corrosion that eats steel frames ridden through winter salt.
Throttle or Pedals, Your Choice
Twist the grip for instant electric acceleration when you want to clear an intersection, or drop into pedal-assist and let the motor top up your own effort. Most riders use both within the same ride, and mixing them is what stretches the 720 Wh pack.
Hub Drive Means Less to Maintain
With the motor inside the rear wheel there is no mid-drive gearbox, no secondary chain, and no belt to tension. The electric drivetrain is effectively sealed, and the bike runs quietly enough to hold a conversation alongside another rider.
Clean Lines from an Integrated Pack
Placing the battery inside the down tube does more than tidy the silhouette. It centres the mass between the wheels for predictable handling, keeps the cells out of direct spray, and makes the bike far less obviously an e-bike when it is locked up in public.
IP45 Rated for Year-Round Use
Sealed connectors, a covered charge port, and an IP45 rating on the electrical assembly mean rain and road spray are part of normal service rather than an emergency. Ride to work in a shower and park outside without worrying about the controller.
Controls & Indicators
Power Button
On the battery pack; hold to switch the system on and off
Mode Buttons
Up and down buttons on the display cycle through the pedal-assist levels plus zero assist
Twist Throttle
Right-hand grip; proportional response, works independently of the assist level
Speedometer
Live speed readout in mph, switchable to km/h in the settings menu
Battery Gauge
Segmented charge indicator with percentage 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 terrain you plan to ride - firmer for tarmac, softer for gravel, sand, or snow.
- Squeeze both brake levers. They should firm up well before touching the grip, and both rotors should spin free of rub when released.
- Confirm the battery is seated and locked in the down tube and that the display shows the expected state of charge.
- Spin both wheels and check that the rims run true and nothing catches on the mudguards.
- Verify the axle nuts are tight and that the headset has no play when you rock the bike with the front brake applied.
- Shift through all seven gears while pedalling slowly to confirm the derailleur indexes cleanly before you need a low gear on a climb.
- Test the throttle at walking pace in a clear area before riding in traffic, especially on your first few rides.
- Switch on the headlight and tail-light for dusk or overcast conditions, and wear a helmet rated for the speeds this bike reaches.
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 cut-off sensors disable the motor while either lever is pulled. If the display shows an error code, note it and contact support.
Range dropped noticeably compared with when it was new.+
Check tire pressure first; soft fat tires on tarmac are by far the most common cause. 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 may be nearing the end of its service life.
The disc brakes squeal or rub.+
Light squeal after wet rides usually clears within a few stops. Persistent rub means the caliper needs recentring over the rotor, or the rotor itself has a slight bend that can be trued with a rotor fork. Contaminated pads must be replaced, not cleaned.
The chain skips under hard pedalling.+
The derailleur indexing is likely out of adjustment, or the chain and cassette are worn. Turn the barrel adjuster a quarter turn at a time to realign the indexing. If the chain skips only in the smallest cogs, replace the cassette together with the chain.
The front fork clunks over bumps.+
Check that the quick-release or axle bolt is fully tightened and that the wheel is seated squarely in the dropouts. If the noise persists, inspect the stanchions for scoring and have a shop service the fork lowers.
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, note the exact code and what you were doing when it appeared, then contact support - codes map to specific faults in the controller, motor, or throttle circuits.
Certifications & Standards
The HKM-6563539 is produced in a facility operating under an ISO 9001 quality management system. The electrical assembly carries an IP45 ingress rating, and the battery cells and assembled pack hold 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.
- IP45 - Ingress protection rating covering rain and road spray on the electrical system.
- UN38.3 - Battery transport safety testing, required for lithium-ion shipping by air, sea, and road.
- 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. Read the manual fully before the first ride and practise throttle control in an open, traffic-free area until the response feels predictable. Fat tires give a reassuring amount of grip, but they do not shorten braking distances at speed.
- Wear a helmet on every ride. At 31 mph a bicycle helmet is the minimum; many riders choose a certified motorcycle or downhill helmet at these speeds.
- Do not exceed the 309 lb (140 kg) load capacity, which includes the rider and all cargo.
- Check local law before riding on public roads or paths. A 750 W motor with a 31 mph top speed may place this vehicle outside standard e-bike classifications in your area.
- Bed in the disc pads with 10-15 progressive stops during the first few rides before riding at full speed.
- The IP45 rating covers rain and spray only. Do not ride through water deep enough to reach the hub motor or the down-tube 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 gravel, wet surfaces, and downhill grades, and brake earlier than you would on a dry road.
HKM-6563539 · 750 W high-speed brushless rear hub (1000 W peak) · 48 V 15 Ah lithium (720 Wh) · 31 mph top speed · 22-31 mi range · 20 x 4.0 in off-road fat tires · 309 lb (140 kg) load capacity · aluminum alloy frame · 7-speed derailleur · double disc brakes · IP45 water resistance. 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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