250W 36V Lightweight Commuter E-Bike
HKM-390035 Electric Commuter Bike
The HKM-390035 is a lightweight commuter built around a 250 W rear hub motor and a generous 36 V 20 Ah pack that returns 40-50 mi between charges. The 27.5 x 2.1 in commuter tires roll efficiently, a 7-speed Shimano drivetrain handles the daily grades, and disc brakes plus integrated LED lighting make it ready for the early or late ride. At about 52 lb it is easy to carry, store, and pedal home if the pack runs low.
250 W Rear Hub Motor36 V 20 Ah Pack20 mph Top Speed40-50 mi Range27.5 x 2.1 in TiresDisc Brakes7-Speed Shimano265 lb Load Capacity
Motor
250 W
Rear hub, 35-45 N.m
Battery
36 V 20 Ah
720 Wh pack
Top Speed
20 mph
32 km/h
Range
40-50 mi
64-80 km per charge
Tires
27.5 x 2.1 in
Commuter tread
Load Capacity
265 lb
120 kg rider plus cargo
Overview
The HKM-390035 is a lightweight electric commuter built for the daily loop rather than the trail. A 250 W rear hub motor paired with a 36 V 20 Ah pack returns 40-50 mi between charges, which is more than most commutes need in a week of riding.
The 27.5 x 2.1 in commuter tires roll efficiently on pavement while still handling a gravel path, and the 7-speed Shimano drivetrain covers the gentle grades of city riding. A comfort fork up front takes the worst of the chatter without adding suspension weight.
Disc brakes bring the bike to a predictable stop in wet or dry conditions, and LED lighting powered from the main pack means it is ready for an early start or a late return without separate batteries. At about 52 lb the bike is easy to carry and store.
A rear rack rated for the commute carries panniers and a lock, and the whole package stays within a 265 lb (120 kg) load capacity that counts rider and cargo together.
Key Features
250 W Brushless Rear Hub Motor
A 250 W brushless rear hub motor drives the HKM-390035. There is no gearbox or second chain between the motor and the road, so drive losses stay low and routine maintenance comes down to keeping the axle hardware torqued and the drivetrain clean.
36 V 20 Ah Lithium Pack (720 Wh)
The 36 V 20 Ah pack stores 720 Wh of usable energy, which is what makes the quoted 40-50 mi (64-80 km) window realistic rather than optimistic. Charging from empty takes 5-6 hours on the supplied charger, and partial top-ups take proportionally less - there is no need to run the pack down before plugging in. A battery management board supervises cell balance, over-charge, over-discharge, and temperature so the pack is protected during both fast riding and long storage.
Light, Simple, Low Maintenance
With no suspension linkage to service and a comfort fork up front, the HKM-390035 stays light and easy to live with. Less mass means more range from the same battery and a bike you can carry up steps without a struggle.
Hydraulic disc brakes, Front and Rear
Sealed hydraulic lines actuate both calipers, so lever effort stays light and predictable when the rotors heat up on a long descent and there are no cables to stretch or corrode. Motor cut-off switches in both levers kill drive the instant either lever moves, which matters on a machine that reaches 20 mph.
7 Speeds for the Daily Loop
A 7-speed Shimano drivetrain covers the gentle grades of a commute without the clutter of a wide cassette. Pair it with pedal-assist and the 250 W motor tops up your effort so hills and headwinds stop being an event.
27.5 x 2.1 in Commuter Tread
The 2.1 in casing is narrow enough to roll efficiently on pavement yet wide enough for a gravel path, and the low-resistance tread keeps the battery range where you want it on a daily ride.
LCD and Integrated Lighting
The backlit LCD reports speed, charge, assist level, and trip distance, and switches units in the settings menu. LED lighting runs from the main pack, so the bike is ready for an early or late ride without extra batteries.
Carry What You Need
A rear rack rated for the commute carries panniers, a lock, and a change of clothes. Keep total load inside the 265 lb (120 kg) capacity, counting rider and cargo together.
Full Specifications
Model
HKM-390035 | Electric Commuter Bike
Frame Material
Lightweight aluminum alloy step-over frame
Motor
250 W brushless rear hub motor, 35-45 N.m rated torque
System Voltage
36 V DC
Battery
36 V 20 Ah lithium-ion (720 Wh), removable and lockable
Charger
2 A smart charger, 100-240 V input
Charging Time
5-6 hours from empty
Battery Cycle Life
Approximately 800 charge cycles to 80 percent of rated capacity
Top Speed
20 mph (32 km/h)
Range Per Charge
40-50 mi (64-80 km), varies with terrain, rider weight, tire pressure, and assist level
Climbing Grade
Up to approximately 15 degrees with a solo rider
Peak Torque
26-33 lb-ft (35-45 N.m)
Drivetrain
7-speed Shimano derailleur with index shifter
Brakes
Hydraulic disc brakes, front and rear, with motor cut-off levers
Suspension
Rigid frame with a comfort-tuned steel fork
Tires
27.5 x 2.1 in tires with a low-rolling-resistance commuter tread
Wheels
27.5 in alloy rims, stainless steel spokes
Saddle and Contact Points
Padded saddle with quick-release seat post clamp, rubber grips
Display
Backlit LCD: speed, charge, assist level, trip distance, odometer
Throttle and Assist
Twist-grip throttle plus multi-level pedal-assist
Lighting
LED headlight and tail-light powered from the main pack
Load Capacity
265 lb (120 kg) rider plus cargo
Vehicle Weight
Approximately 52 lb (24 kg) including battery
Recommended Rider Height
5 ft 4 in to 6 ft 2 in (163-188 cm)
Certifications
CE, RoHS; battery cells UN38.3 tested
Battery, Range, and Charging
The 36 V 20 Ah pack holds 720 Wh. Most mainstream commuter e-bikes ship with 400-600 Wh, so this pack sits well above that band, and the extra energy is what turns a nervous end-of-day commute into an ordinary one.
Real-world range moves with four things more than anything else: how much you pedal, total rider and cargo weight, tire pressure, and terrain. Throttle-heavy riding at the top of the speed range sits at the low end of the 40-50 mi (64-80 km) window. Moderate assist on rolling terrain lands in the middle. Light assist on level ground with a steady cadence is what produces the high figure. Cold weather below 40 F (4 C) temporarily trims available capacity by 10-20 percent; the capacity comes back once the pack warms up again.
Tip: Store the pack between 30 and 70 percent state of 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 charge port is reachable without removing anything, and the supplied 2 A charger runs on 100-240 V so it works on household power anywhere. Two keys are included. Charge after a ride rather than the next morning: a pack that goes into storage warm and full ages faster than one that is topped up and then left at room temperature.
Daily Use & Care
- Tire pressure sets the character of the ride. Run the upper half of the sidewall pressure range on pavement for lower rolling resistance, and drop toward the lower half on gravel or 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 aluminum and steel fasteners over time if it is left in place.
- Check the axle hardware and stem bolts before the first ride of each week. Motor torque works fasteners 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. A dry chain wears the Shimano cassette far faster than a clean, oiled one.
- Inspect brake pad thickness monthly. Pads wear silently until they are gone; replace the friction material once it is under 1 mm.
- 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 when the bike is parked outside so moisture stays out of the connectors.
- Torque the 27.5 in spoke nipples and check wheel true after the first 50 mi. New wheels bed in, and a 52 lb machine loads the spokes harder than a conventional bicycle does.
What's in the Box
- 1 x HKM-390035 bike, approximately 85 percent pre-assembled
- 1 x 36 V 20 Ah lithium battery pack
- 1 x 2 A smart charger with 100-240 V input
- 2 x Battery or lock keys
- 1 x Pair of pedals
- 1 x Toolkit with hex wrenches and pedal spanner
- 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, straightening and bolting the handlebar, installing the pedals and saddle, and checking brake alignment and rotor clearance. Budget 30-45 minutes with the supplied tools, and have a shop check torque and bed the brakes in if you are not comfortable doing that yourself.
What range should I actually plan for?+
Plan for 40-50 mi (64-80 km). Headwinds, hills, cold weather, heavier riders, and low tire pressure all pull the figure down; a warm day, firm tires, and a steady pedaling cadence push it back up.
How long does the battery take to charge?+
About 5-6 hours with the supplied charger from a fully empty pack. Partial top-ups take proportionally less time, and the pack does not need to be run down before recharging. Charging with the pack on board works exactly as well as charging it on a bench.
Is 250 W enough for hills?+
For the moderate grades of a typical commute, yes, especially with the 7-speed gears letting you contribute pedal power. The motor is rated for gentle climbs; on a long steep grade, shift down and pedal along with it.
How far will it go on a charge?+
Plan for 40-50 mi (64-80 km) under moderate pedal-assist on level ground. Headwinds, hills, cold weather, heavier riders, and low tire pressure all pull the figure down; a steady cadence pushes it back up.
Is a license or registration required?+
Rules vary by state and by city. The common three-class US e-bike framework caps assisted speed at 20 or 28 mph and motor output at 750 W, and this machine is documented at 20 mph with a 250 W rating, so it may fall outside class limits where you live and be treated as a moped or motor-driven cycle. Check your state DMV and local ordinances before riding on public roads or shared paths.
Can I ride it with the motor switched off?+
Yes. The 7-speed Shimano drivetrain works independently of the motor. At roughly 52 lb the machine is heavy for unassisted pedaling, so getting home on a flat pack is slow but entirely possible on level ground.
Is the battery removable for indoor charging?+
Yes. It unlocks with the supplied key and lifts out for charging at a desk while the bike stays locked outside. You can also charge it in place through the frame-side port.
Service & Policies
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Every order ships free. Handling Time: 0-1 business days (Monday to Friday). Transit Time: 2-5 business days (Monday to Friday). A tracking number is emailed as soon as the parcel leaves our warehouse.
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24 Months Warranty Service
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 Battery720 Wh PackHydraulic disc20 mph40-50 mi Range
Why Choose the HKM-390035
Efficient by Design
A 250 W motor and a 720 Wh pack is a combination that favours distance over brute force. The HKM-390035 is built to cover the daily commute on a single charge with range to spare.
Light Enough to Live With
At about 52 lb the bike is easy to maneuver in a hallway, lift onto a rack, and pedal unassisted if the pack runs low. Light weight is a feature you feel every day, not just on the spec sheet.
Two Ways to Ride
Twist the throttle for immediate, clutch-free acceleration, or shift through the 7-speed Shimano drivetrain and pedal. Most owners mix both: throttle to pull away from a stop, gears and pedal-assist to stretch the range on the flat, and full power for the hills.
Low-Maintenance Drivetrain
The motor lives inside the rear wheel hub. No mid-drive gearbox, no belt, and no extra chain sit in the drive path, so there is very little to service and the ride stays notably quiet even at full power.
Low Running Cost, No Fuel Stops
A full 720 Wh charge costs a few cents of household electricity and covers 40-50 mi (64-80 km). There is no fuel, no oil change, and no emissions test. For trips under 10 mi the bike is usually quicker door to door than a car once parking is counted, and it removes a daily short-trip journey from the vehicle that costs the most to run.
Everyday Practicality
Disc brakes, integrated lights, a 7-speed drivetrain, and a commuter tread are the four things that make a bike genuinely useful for transport rather than just recreation. The HKM-390035 has all four.
Controls & Indicators
Power Button
Located on the battery pack; hold to switch the system on and off
Assist Level Buttons
Up and down buttons on the display cycle through the pedal-assist levels plus zero assist
Throttle
Right-hand twist grip; proportional response, works independently of the assist level
Speedometer
Live speed readout in mph, switchable to km/h in the display settings menu
Battery Gauge
Segmented state-of-charge indicator plus voltage or percentage readout on the display
Light Switch
Long-press the up button to toggle the LED headlight and tail-light
Shifter
Right-hand index shifter for the 7-speed Shimano rear derailleur
Pre-Ride Safety Checklist
- Check tire pressure and set it for the surface you plan to ride; pressure has more effect on range and grip than any other single adjustment you can make in 30 seconds.
- Squeeze both brake levers. They should firm up well before touching the grip, with no sponginess or long lever travel.
- 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 that nothing rubs a brake pad or the frame.
- Check that the axle hardware is tight and that the headset has no play when you rock the machine with the front brake applied.
- Test the throttle at walking pace in a clear, traffic-free area before riding in traffic.
- Switch on the headlight and tail-light if you will be riding near dusk, and wear a helmet rated for the speed this machine reaches.
- Confirm that the display reads the assist level you expect before you set off, so the first throttle input is not a surprise.
Quick Troubleshooting
The motor does not engage when I twist the throttle.+
Confirm the display is on and showing charge, the battery is locked into place, and both brake levers are fully released - the brake cut-off sensors disable drive while a lever is pulled. If the display shows an error code, note the code and contact support.
Range dropped noticeably compared with when it was new.+
Check tire pressure first; a soft tire on pavement is the most common cause. Then consider temperature, because 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 feel spongy or the lever pulls to the grip.+
Sponginess in a hydraulic system normally means air in the line or a fluid leak. Stop riding and have the system bled and inspected - do not continue on a 20 mph machine with compromised brakes.
The chain skips under hard pedaling.+
The Shimano indexing is 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, the cassette is worn and should be replaced together with the chain.
There is a rattle or knock from the suspension over bumps.+
Check that the axle and any quick-release lever are fully closed and that the wheel is seated in the dropouts. If the noise persists, inspect the stanchions or shock body for scoring and have a shop service the unit.
The display shows an error code and the machine will not move.+
Switch the system off, wait 30 seconds, and switch it back on. If the code returns, note the exact code and the conditions that produced it, then contact support - error codes map to specific faults in the controller, motor, throttle, or battery circuits.
Certifications & Standards
The HKM-390035 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.
- CE - European Conformity marking covering the electrical assembly.
- RoHS - Restriction of Hazardous Substances compliance for the electronics.
- UN38.3 - Lithium battery transport safety testing, required for 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 250 W machine documented at 20 mph. Read the manual before the first ride and practise throttle control and braking in an open, traffic-free area until the response feels predictable. Braking distance grows quickly with speed and with load, so leave more room than a conventional bicycle needs.
- Wear a helmet on every ride. At 20 mph a standard bicycle helmet is the minimum; many riders choose a certified downhill or motorcycle helmet at these speeds.
- Do not exceed the 265 lb (120 kg) load capacity, which includes the rider, any cargo, and anything carried on a rack.
- Check local law before riding on public roads or shared paths. A 250 W system with a 20 mph top speed may sit outside standard e-bike classifications in your area.
- Bed the brake pads in with 10-15 progressive stops from moderate speed during the first few rides before riding at full speed.
- Do not ride through water deep enough to reach the motor housing or the battery compartment.
- Charge only with the supplied charger, indoors, at room temperature, on a non-flammable surface, and do not leave a charging pack unattended overnight.
- Do not open, puncture, or modify the battery pack. Damaged lithium cells can vent and ignite.
- Reduce speed substantially on gravel, wet surfaces, and steep descents. Wide tires add grip but they do not change the physics of losing traction at speed.
HKM-390035 · 250 W rear hub motor · 36 V 20 Ah lithium (720 Wh) · 20 mph top speed · 40-50 mi range · 27.5 x 2.1 in tires · 265 lb (120 kg) load capacity · hydraulic disc brakes · lightweight aluminum frame. 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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