Dual-Battery Full-Suspension Fat Tire eMTB
HKM-8988371 Electric Mountain Bike
The HKM-8988371 runs two removable 52 V 15 Ah lithium packs in parallel - 30 Ah and roughly 1560 Wh combined - which is what puts more than 60 mi (96 km) within reach on pedal assist. The rear hub motor is rated 1000 W continuous with 2000 W available on peak and 85 N.m of torque for steep grades, taking the bike to 31 mph (50 km/h). A front fork and a rear coil shock make it a genuine full-suspension chassis rather than a hardtail with soft tires, and 20 x 4.0 in fat rubber floats over sand, snow, and loose gravel. Hydraulic discs on 180 mm rotors, a 7-speed drivetrain, a 600-lumen integrated headlight, and a 330 lb load rating complete it.
2000 W Peak / 1000 W RatedDual 52 V 15 Ah Packs1560 Wh Combined85 N.m Torque31 mph Top Speed60+ mi Range20 x 4.0 in Fat TiresFull Suspension
Motor
2000 W Peak
1000 W rated rear hub, 85 N.m
Battery
52 V 30 Ah
1560 Wh across two removable packs
Top Speed
31 mph
50 km/h, mode dependent
Range
60+ mi
96+ km on pedal assist level 2
Tires
20 x 4.0 in
Fat tread, sand snow gravel
Load Capacity
330 lb
150 kg rider plus gear
Overview
The defining decision on the HKM-8988371 is the 52 V architecture. Most e-bikes in this class run 48 V; stepping up to 52 V means the same power is delivered at lower current, which reduces resistive losses in the controller and the motor windings and keeps voltage sag under heavy load smaller. In practice that shows up as a bike that holds its power more consistently on a long climb rather than fading as the pack depletes.
Two 15 Ah packs work in parallel for 30 Ah and roughly 1560 Wh combined, monitored by a smart battery management system that balances discharge across both. Because they are removable and independent, you can charge one while riding on the other, which effectively doubles what you can cover in a day. Each pack takes 4-5 hours to charge, and an optional dual charger handles both at once.
The motor is rated 1000 W continuous with 2000 W on peak, producing 85 N.m of torque. That torque figure matters more than the wattage on a trail bike: it is what determines whether you can restart on a steep loose section rather than having to push. Top speed is 31 mph (50 km/h). A sine-wave controller keeps the motor quiet and supports regenerative braking assistance, recovering a small amount of energy on long descents.
Suspension is a front fork paired with a rear coil shock, with preload adjustable to suit rider weight up to the 330 lb (150 kg) limit. Full suspension plus 4 in tires at 5-30 psi is a combination that substantially reduces fatigue on long rough rides - the tires absorb high-frequency chatter while the shock and fork handle the larger hits that would otherwise reach the rider directly.
Key Features
2000 W Peak Rear Hub Motor, 85 N.m Torque
Rated at 1000 W continuous with 2000 W available on demand, the rear hub motor produces 85 N.m of torque - enough to restart on a steep loose climb rather than having to dismount and push. Because drive goes straight from the hub to the ground, the chain and cassette carry no motor load and wear at normal bicycle rates.
Dual 52 V 15 Ah Removable Packs (1560 Wh)
Two independent packs run in parallel under a smart BMS that balances load between them and manages charge cycles to extend life. Each charges in 4-5 hours, or both together with an optional dual charger. The removable design means you can ride on one while the other is on charge, which is what makes back-to-back long days practical.
Full Suspension: Front Fork and Rear Coil Shock
A suspension fork at the front and a coil shock at the rear keep both wheels tracking over roots and rock instead of skipping across them. Preload is adjustable at both ends to match rider weight up to the 330 lb limit. On long, rough rides the reduction in fatigue compared with a hardtail is the difference between finishing strong and finishing sore.
Hydraulic Disc Brakes, 180 mm Rotors
Sealed hydraulic systems with 180 mm rotors front and rear give progressive bite with fine modulation, which is what you want on loose surfaces where grabbing a brake locks a wheel. Lever feel stays precise in wet and dusty conditions, and the sealed lines need markedly less maintenance than cable-actuated brakes.
7-Speed Drivetrain with Index Shifter
A 7-speed cassette gives a usable pedalling cadence from a slow technical climb up to cruising speed. Keeping the gears mechanical and the motor in the hub means the drivetrain stays simple and cheap to service, and you can still pedal the bike home comfortably if both packs run flat.
20 x 4.0 in Fat Tires, 5-30 psi
Four-inch casings on 20 in rims run anywhere from 5 to 30 psi. Low pressure lets the tire flatten and float over sand, powder snow, and loose gravel; higher pressure rolls efficiently on pavement. Combined with the dual suspension, the wide casing absorbs trail chatter that would otherwise reach the rider.
Integrated 600-Lumen LED Headlight
A 600-lumen integrated headlight runs from the main packs, so there is nothing separate to charge. That output is enough to pick a line on unlit trail at moderate speed and to make you clearly visible in traffic long before dusk.
Steel Frame with Internal Cable Routing
The high-carbon steel frame damps vibration in a way aluminum does not and tolerates repeated impact loading well. Internal cable routing keeps brake lines and wiring inside the tubes, protected from snagging on branches and from the grit and spray thrown up by the front tire.
Full Specifications
Model
HKM-8988371 | Electric Mountain Bike
Frame Material
High-carbon steel with internal cable routing
Motor
1000 W rated rear hub motor, 2000 W peak, 85 N.m torque
System Voltage
52 V DC with sine-wave controller
Battery
Dual 52 V 15 Ah lithium-ion, 30 Ah combined (approximately 1560 Wh), removable
Charger
Smart charger, 100-240 V input; optional dual charger available
Charging Time
4-5 hours per pack from empty
Battery Cycle Life
Approximately 800 charge cycles to 80 percent capacity
Top Speed
31 mph (50 km/h), mode dependent
Range Per Charge
60+ mi (96+ km) on pedal assist level 2; 35-40 mi (56-64 km) throttle only
Climbing Grade
Steep grades within the 85 N.m torque rating with a solo rider
Peak Torque
85 N.m
Drivetrain
7-speed derailleur with index shifter
Brakes
Hydraulic disc brakes, 180 mm rotors front and rear
Suspension
Front suspension fork plus rear coil shock, adjustable preload
Tires
20 x 4.0 in fat tires, 5-30 psi working range
Wheels
20 in rims, spoked build sized for fat tire casings
Cockpit
Adjustable stem and seat post, thumb-access control buttons
Display
Backlit LCD: speed, battery percentage, odometer, assist level
Throttle
Twist throttle with multi-level pedal assist and zero assist
Lighting
Integrated 600-lumen LED headlight powered by the main packs
Load Capacity
330 lb (150 kg) rider plus gear
Bike Weight
79 lb (36 kg) with both battery packs fitted
Recommended Rider Height
5 ft 3 in to 6 ft 4 in (160-193 cm)
Certifications
CE, RoHS; IP65 motor and battery connectors; cells UN38.3 tested
Battery, Range, and Charging
Two 52 V 15 Ah packs give 30 Ah and approximately 1560 Wh combined. The 52 V architecture is the part worth understanding: at higher voltage the same power is delivered at lower current, which cuts resistive losses in the controller and windings and reduces the voltage sag you feel as a power drop under sustained load. The result is a bike that holds its output more consistently across a long climb than a 48 V equivalent.
On pedal assist level 2, riders can expect more than 60 mi (96 km). Throttle-only riding on flat terrain with a 180 lb (82 kg) rider and both packs fitted lands around 35-40 mi (56-64 km). The smart BMS balances discharge across both packs and optimises charging cycles. The sine-wave controller also supports regenerative braking assistance, recouping a modest amount of energy on long descents.
Tip: Each pack charges in 4-5 hours from empty. Because the packs are independent and removable, charging one while riding on the other is the simplest way to extend a long day - it effectively doubles your daily range without carrying extra weight on the bike.
The controller draws from both packs in parallel automatically, with no switching for the rider to manage. You can also remove one pack and run on a single battery, which reduces weight for shorter rides. An optional dual charger refills both simultaneously if you would rather not charge sequentially overnight.
Daily Use & Care
- Set tire pressure for the surface: 20-30 psi on pavement and hardpack, 5-12 psi for sand, snow, and soft ground.
- Check the rear shock and fork preload settings match your current riding weight, especially if you have started carrying a pack.
- Clean and lubricate the chain every 100-150 mi, and after any ride through water, sand, or heavy dust.
- Wipe the fork stanchions and the shock shaft after dirty rides so grit is not dragged past the seals on the next compression.
- Inspect hydraulic brake pad thickness monthly and replace before the friction material drops below 1 mm.
- Rinse salt and mud off the steel frame and dry it afterwards, and touch up paint chips promptly to prevent rust taking hold.
- Re-torque the rear axle nuts and the suspension pivot hardware every few weeks; hub-motor torque works fasteners loose faster than a normal drivetrain.
What's in the Box
- 1 x HKM-8988371 electric mountain bike, partially pre-assembled
- 2 x Removable 52 V 15 Ah lithium battery packs
- 1 x Smart charger with 100-240 V input
- 2 x Battery keys
- 1 x Assembly toolkit with hex wrenches and pedal spanner
- 1 x Pair of platform pedals
- 1 x Spare brake pad set
- 1 x User manual and assembly guide
Frequently Asked Questions
What is the actual range on throttle only?+
On flat terrain with a 180 lb (82 kg) rider and both packs fitted, expect approximately 35-40 mi (56-64 km) using throttle only. Pedal assist level 2 pushes that past 60 mi (96 km). Hills, headwind, cold weather, soft tires, and a heavier rider all reduce those figures.
How does the dual-battery system switch between packs?+
It does not switch - the controller draws from both packs in parallel automatically, and the BMS balances the load between them. There is nothing for the rider to manage. You can also remove one pack and operate on a single battery if you want to save weight.
Why 52 V instead of the more common 48 V?+
Higher voltage delivers the same power at lower current, which reduces resistive losses in the controller and motor windings and lessens the voltage sag that feels like a power drop under load. On sustained climbs the bike holds its output more consistently as a result.
Is it really full suspension?+
Yes. There is a suspension fork at the front and a coil shock at the rear, both with adjustable preload, rather than a hardtail frame relying on tire volume alone. Combined with the 4 in tires, that makes a substantial difference to fatigue on long rough rides.
Is the bike waterproof?+
The motor and battery connectors are IP65 rated, so rain and splashes are well tolerated. Avoid submersion - do not ride through water deep enough to reach the hub motor or the battery compartments - and dry the bike after wet rides.
How long does charging take?+
Four to five hours per pack from empty. With the single supplied charger you charge them one after the other; an optional dual charger refills both at the same time.
Can I pedal it if both packs run flat?+
Yes. The 7-speed drivetrain works entirely independently of the motor. At 79 lb the bike is heavy, so unassisted pedalling is slow going, but it is perfectly possible on flat ground and gives you a way home.
Do I need a license or registration?+
Rules vary by state and locality. A 2000 W peak motor and a 31 mph top speed exceed 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 trails.
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CERoHSUN38.3 BatteryIP65 Connectors1560 Wh Dual PackFull Suspension85 N.m Torque
Why Choose the HKM-8988371
52 V Where Others Use 48 V
The voltage step-up is not a spec-sheet flourish. Lower current for the same power means less heat in the controller and windings, less voltage sag under load, and more consistent output as the pack depletes. It is the kind of decision you feel on the third climb, not the first.
Full Suspension, Not Just Fat Tires
Plenty of fat-tire e-bikes rely on tire volume alone and call it comfort. A real fork and a real rear coil shock keep both wheels in contact with the ground over roots and rock, which improves traction and control as much as it improves comfort.
85 N.m Where It Counts
Torque, not wattage, determines whether you can restart on a steep loose section. At 85 N.m the motor pulls away cleanly from a standstill on gradients that would have you pushing a lower-torque bike, which is what makes technical climbs enjoyable rather than tedious.
Sine-Wave Control and Regen Support
The sine-wave controller drives the motor smoothly instead of in blocks, so the bike hums rather than whines, and it supports regenerative braking assistance that recovers a little energy on long descents. Less noise, slightly more range, no extra hardware.
Charge One, Ride the Other
Two independent removable packs mean you are never waiting for the bike to be ready. Charge one overnight while the other is on the bike, swap in the morning, and repeat. For back-to-back long days that is more useful than any single pack.
IP65 Sealing and Internal Routing
IP65-rated motor and battery connectors handle rain and splashes as normal operating conditions, while internal cable routing keeps brake lines and wiring inside the tubes, away from branches and away from the spray the front tire throws up.
Controls & Indicators
Power Button
Switches the system on and off and wakes the backlit LCD
Mode Buttons
Thumb-access buttons cycle assist levels without removing hands from the grips
Twist Throttle
Right-hand grip; proportional response, independent of the assist level selected
Speedometer
Live speed on the LCD, switchable between mph and km/h
Battery Gauge
Battery percentage shown for the combined dual-pack system
Light Switch
Toggles the integrated 600-lumen headlight from the handlebar
Preload Adjusters
Set fork and rear shock preload to match rider weight and terrain
Pre-Ride Safety Checklist
- Set tire pressure for the terrain: 20-30 psi for pavement, 5-12 psi for sand, snow, or soft ground.
- Squeeze both brake levers. They should firm up well before the grip with no sponginess indicating air in the hydraulic line.
- Confirm both packs are seated and locked and that the LCD shows the state of charge you expect.
- Check fork and shock preload for your weight and today terrain before you leave rather than partway up the trail.
- Spin both wheels and check they run true and that nothing rubs the pads or the frame.
- Re-check the rear axle nuts and suspension pivot bolts for torque, particularly after any hard ride.
- Confirm the 7-speed drivetrain shifts cleanly through the full range before you rely on it on a climb.
- Switch on the headlight for low-light riding and wear a helmet rated for the 31 mph this bike reaches.
Quick Troubleshooting
The motor does not engage when I twist the throttle.+
Confirm the LCD is on and showing charge, that at least one pack is seated and locked, and that both brake levers are fully released, since the cut-off sensors disable drive while a lever is pulled. Note any error code displayed before contacting support.
One pack drains noticeably faster than the other.+
A small divergence is normal as packs age at slightly different rates. A large and growing gap points to a weak cell group. Charge each pack fully, ride each one individually and note the range delivered, then pass those figures to support.
The brakes feel spongy at the lever.+
Sponginess in a hydraulic system means air in the line or a fluid leak. Stop riding and have the system bled and inspected. Do not continue on a 31 mph bike, or start a descent, with compromised brakes.
The rear shock bottoms out on every hit.+
Preload is set too soft for your weight. Wind it in progressively until the shock uses most but not all of its travel on typical hits. If maximum preload still bottoms out, the spring rate is too low for your riding weight and the spring should be changed.
The chain skips under hard pedalling.+
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 skipping happens only in the smallest cogs, the cassette is worn and should be replaced with the chain.
The LCD 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 battery circuits.
Certifications & Standards
The HKM-8988371 is produced in a facility operating under an ISO 9001 quality management system. Both battery packs carry the test documentation normally required for lithium-ion transport and sale, and the motor and battery connectors are rated IP65 against dust and low-pressure water jets.
- 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.
- IP65 - Dust-tight and protected against low-pressure water jets, covering the motor and battery connectors.
- ISO 9001 - Quality management system certification held by the manufacturing facility.
Important Safety Notes
This is a high-output electric mountain bike capable of 31 mph (50 km/h) with 85 N.m of torque available from a standstill. Read the manual fully before the first ride and practise throttle control in an open, traffic-free area. On trail, build up to technical terrain gradually - the torque can lift the front wheel on a steep loose restart more readily than riders expect.
- Wear a helmet on every ride. At 31 mph a bicycle helmet is the minimum; a full-face helmet is appropriate for technical trail riding.
- Do not exceed the 330 lb (150 kg) load capacity, which includes the rider and all carried gear.
- Check local law before riding on public roads or trails. A 2000 W peak motor and 31 mph top speed may place this vehicle 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 pace or starting a long descent.
- Set fork and shock preload for your weight before riding rough terrain; suspension set too soft will bottom out harshly on square-edged hits.
- IP65 covers rain and splashes, not submersion. Do not ride through water deep enough to reach the hub motor or the battery compartments.
- Charge only with the supplied charger, indoors, at room temperature, on a non-flammable surface, and do not leave packs charging unattended overnight.
- Do not open, puncture, or modify either battery pack. Damaged lithium cells can vent and ignite.
HKM-8988371 · 1000 W rated rear hub motor (2000 W peak), 85 N.m torque · dual 52 V 15 Ah lithium packs (30 Ah, approximately 1560 Wh) · 31 mph (50 km/h) top speed · 60+ mi (96+ km) range on pedal assist · 20 x 4.0 in fat tires · front fork and rear coil shock full suspension · hydraulic disc brakes with 180 mm rotors · 7-speed drivetrain · integrated 600-lumen LED headlight · high-carbon steel frame with internal cable routing · 330 lb (150 kg) load capacity · 79 lb (36 kg) with both packs. Specifications are provided for reference; actual performance varies with rider weight, terrain, tire pressure, temperature, and riding style. Range figures are measured under pedal-assist level 2 on level ground. This page describes the product only and is not legal advice regarding vehicle classification - confirm local regulations before riding on public roads or trails.
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