Balance Bikes >>
HKM-3581139 12-Inch Electric Balance Bike for Kids 3-8 Years with 250W Brushless Motor, 36V Lithium Battery and Rear Disc Brake
HKM-3581139
A First Powered Bike With Real Brakes
The HKM-3581139 keeps everything a three-year-old needs and nothing they do not. A 250W brushless motor turns the rear wheel from a 36V 2.5Ah pack that unclips for charging, a rear disc brake answers one small lever, and the power-cut brake lever stops the motor the instant it is pulled. Two speed options let parents choose how eagerly the throttle responds, the 12-inch knobby tires grip grass and pavement alike, and the aluminium frame keeps the bike light enough to carry home when little legs run out.
Key Features
Six details that make the HKM-3581139 a calm first bike.
A 250W Brushless Hub Motor
The motor sits in the rear wheel, so drive goes straight into the tire with no chain and nothing hot near small legs. It pulls smoothly from a standstill, which is exactly what a rider learning the throttle needs.
Two Speed Options
The parent switch sets how eagerly the motor answers, gentle for the first weeks and livelier once the rider steers and brakes without reminders. It is the simplest way to make one bike serve a three-year-old and a seven-year-old.
A Rear Disc Brake
One lever works one disc with a predictable bite, the easiest braking lesson a small hand can be given. Because a disc ignores wet grass, the stop a rider learns on day one stays the same all season.
A Power-Cut Brake Lever
Pulling the brake cuts motor power instantly, so grabbing the brakes is always the winning move. It is a small feature that removes the worst-case scenario, and it teaches brakes outrank throttle from the very first ride.
A Battery That Unclips
The 36V 2.5Ah pack releases from its frame mount in seconds and charges indoors on a bench. The bike never has to sit beside a socket, and the routine fits family life rather than fighting it.
A Frame Sized for First Rides
The aluminium alloy frame keeps the weight low and light, the 12-inch wheels keep the saddle close to the ground, and both feet stay flat while seated. Rated to a 3-8 age span, it covers the whole first-bike window.
Overview
A 12-inch electric balance bike with a power-cut brake and removable battery.
The HKM-3581139 is a 12-inch electric balance bike for riders aged three to eight, built around a calm introduction to powered riding. A 250W brushless rear hub motor draws from a 36V 2.5Ah lithium pack that unclips for bench charging, and a rear disc brake provides one consistent, easy-to-learn stop. A power-cut brake lever kills the motor the moment it is pulled, and two selectable speed options let a parent tune the throttle from gentle to lively. The aluminium frame and 12-inch knobby tires keep the bike light, low and planted on grass and pavement alike, which is exactly where first riders start.
Small Bike, Serious Brake
One lever, one disc, motor cut on grab.
The rear disc gives a predictable stop, and the power-cut lever makes grabbing the brake the always-correct answer. That is the whole braking lesson, learned in one ride. The lever sits where a small hand already rests.
Full Specifications
Everything worth knowing, in one table.
Why 12 Inches Is the Right Start
Wheel size sets the confidence level.
At three years old, the ground is a long way away, and wheel size decides how far the fall feels. The 12-inch wheels keep the saddle low enough for both feet to plant flat, which is the position every young rider checks before they check anything else. The knobby tires hold their line on grass and gravel, so the bike does not wander when the rider is busy learning the throttle. The rigid fork keeps the front end light and direct, and the aluminium frame means a parent can carry the whole thing home one-handed when the session ends in tears or sleep. Two speed options and the power-cut brake close the loop: the bike starts gentle, and the rider always holds the stronger hand.
What’s in the Box
What arrives in the box, ready to build.
1 x 12-Inch Balance Bike
Frame, fork, wheels and motor factory-fitted
1 x 36V 2.5Ah Battery
Pack seated in its frame mount
1 x Battery Charger
Mains charger matched to the pack
1 x Saddle and Post
Fitted, ready to set for leg length
1 x Manual and Tools
Setup sheets plus the hex keys needed
1 x Warranty Card
Registration details for warranty coverage
Why Choose the HKM-3581139
Six reasons families start on the HKM-3581139.
It Starts at Three
A low saddle, a light frame and feet-flat geometry mean the bike works as soon as a child walks with confidence. The gentle speed mode keeps the first powered metres slow, and the brake is one small finger away.
Parents Hold the Switch
The two speed options are a parent control, not a toy. Set the throttle soft for the driveway and livelier for the park, and the bike grows with the rider without buying anything new.
Brakes Outrank Throttle
The power-cut lever means every brake grab is also a motor cut, so the worst case is always a clean stop. Riders learn the hierarchy in one session, and parents stop worrying about stuck throttles.
Charging Fits the Kitchen
The pack unclips and charges on a bench, so there is no garage socket and no bike parked by the wall overnight. A routine that fits family life is the one that actually happens.
Nothing to Service Weekly
A hub motor has no chain to oil and no sprocket to align. The checklist is a wipe-down, a tyre-pressure glance and a brake squeeze, which takes less time than finding the helmet.
Carry-Home Light
First rides end where they run out, not where the car is parked. The aluminium frame keeps the bike light enough to carry in one hand, which turns every ending into an easy one.
Frequently Asked Questions
Straight answers about the HKM-3581139.
What ages does the HKM-3581139 suit?
The bike is designed for riders from three to eight, with leg length as the practical measure: both feet should rest flat while seated. The low saddle and 12-inch wheels put most confident walkers in range on day one, and the seat post has rise for the years that follow. Measure inside leg before ordering to confirm the fit. The gentle mode is what makes the youngest end of that range realistic.
How do the two speed options differ?
The switch changes how eagerly the motor answers the throttle, not a hard speed cap. Gentle mode rolls in slowly, which suits a rider still connecting throttle with movement, and the livelier mode suits one who rides with their eyes up. Start gentle and move up when steering and stopping need no reminders. The change is immediate and reversible, so testing both on a quiet driveway costs nothing.
What does the power-cut brake lever do?
The brake lever carries a sensor that kills motor power the instant it moves, before the pads even reach the disc. Grabbing the brakes is therefore always the correct answer, in any speed mode and any situation. It is the same principle full-size e-bikes use, sized down for small hands. The motor stays cut for as long as the lever is held, so a squeezed brake is a full pause.
Is a 250W motor enough?
For a 12-inch balance bike and a rider under eight, yes, and it is the right amount. The pull is brisk enough to feel real on grass and pavement while staying calm enough to supervise. The two speed options mean the motor never has to outrun the rider’s judgement. At these rider weights, even grass climbs stay within its pull.
How long does the 2.5Ah battery last?
Run time depends on the speed option and terrain, with gentle-mode cruising stretching the 36V 2.5Ah pack across a long session for a small rider. The pack releases for indoor charging and completes a full cycle in a few hours. Families who stack sessions usually add a second pack rather than a bigger bike. A habit of charging after every ride matters more than the exact number of minutes.
What assembly and upkeep are involved?
Assembly covers the handlebar, saddle height and battery seating, with the supplied hex keys and a manual that uses the same part names as the bike. Upkeep is a short list: tire pressure, a brake squeeze test and a wipe-down. The hub motor means there is no chain anywhere on the bike. Most families finish in one evening, with the saddle height left for the rider to try.
Quick Troubleshooting
When the HKM-3581139 needs attention, start here.
The bike will not power on
Unclip the pack and seat it back until the latch clicks, because a pack just short of home makes no contact. Press the power button and watch the indicator. If it stays dark, charge for half an hour and retry, check the mount contacts for grit, and confirm the wall socket with another device first. If the pack was charged recently, let it cool before seating, because a warm pack can trip the mount protection.
The brake feels soft
Check the lever first: it should bite well before half travel. Take up slack at the barrel adjuster, then check the cable anchor at the calliper. A rotor touched by oily fingers will glaze and lose bite, so clean it with isopropyl alcohol and replace pads that have soaked through. After any pad or cable work, squeeze the lever hard ten times to seat everything, then recheck the bite point.
The power-cut stopped working
The cut-out lives in the lever body, so check the lever connector first, because a half-seated plug imitates a dead sensor. Confirm the motor stops when the lever moves a few millimetres. If the cut still does not trigger, keep to gentle mode and contact support before the next session. Never spray cleaner directly at the lever body; damp cloth only, because the sensor lives behind the seal.
The battery refuses to charge
Watch the charger indicator when the pack connects, and make sure both connectors seat fully. Dust in the port is the easiest fix with a dry cloth, and a cold pack refuses a fast charge until it warms indoors. A charger that never changes state is more often the culprit than the pack. Store the pack between half and full charge if the bike will rest for more than a month.
Run time keeps getting shorter
Compare riding style first, because lively mode with repeated starts uses far more per minute than gentle cruising. Check both tire pressures, since soft tires cost range twice. Cold weather trims every lithium pack. If nothing has changed, run one full uninterrupted charge cycle and retest. A pack that cycles weekly for two seasons may simply be ageing out, which is normal wear.
The throttle feels uneven
A pack running low makes the motor surge under load, so start with a full charge in gentle mode. Check the throttle connector for a half-seated plug and keep the grip area clean. If the surging continues with everything checked, note when it happens and contact support about the controller. Water crossings deeper than the hub are best walked, since a soaked connector can mimic a throttle fault.
Service & Policies
Coverage that keeps working long after the bike box arrives.
Free Shipping on All Orders
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.
180 Days Purchase Protection
Your purchase is protected for 180 days from the delivery date against manufacturing defects and damage in transit. If something arrives wrong, we make it right.
30 Days Money Back Guarantee
Not completely satisfied? Request a return within 30 days of delivery for a full refund. We keep the process simple and hassle-free.
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.
Important Safety Notes
Read these notes before the first ride on the HKM-3581139.
The HKM-3581139 is a powered bike for riders aged three to eight, so an adult stays within arm’s reach on every ride. A certified helmet goes on before the first throttle press, with closed shoes and a clear, flat riding area for the early sessions. Begin in gentle speed mode and let the rider learn the throttle at walking pace before any real speed, keeping sessions short while the braking habit forms. Check that the battery is fully latched before each ride, keep fingers and loose clothing clear of the rear hub and the disc while the wheel turns, and never carry a passenger on the frame or the saddle. Charge the pack indoors at room temperature on a hard surface, and unplug once the indicator shows full.
HKM-3581139 - 12-inch electric balance bike for kids aged three to eight, with a 250W brushless rear hub motor, a 36V 2.5Ah removable lithium battery, two selectable speed options, a rear disc brake with a power-cut lever, 12-inch knobby tires and a lightweight aluminium alloy frame. Read the manual before first use. Nothing here is safety certification advice.
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Every part warranted for two full years.
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+1 (209) 280-3200
support@hekomart.com
Address
3401 Dale Rd, Modesto, CA 95356
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