Quick verdict: The RFN Warrior SX-E400 is an excellent first electric motocross-style bike for younger riders who want something more substantial than a traditional electric balance bike.
Best for: riders aged around 3–6 and approximately 90–110cm tall who already balance confidently and want manageable power, suspension and parental speed control.
RFN Warrior SX-E400 Review
The RFN Warrior SX-E400 is the smallest model in the RFN Warrior Kids electric dirt-bike range. It is designed to give younger riders the look and feel of a proper miniature motocross bike while keeping the size and performance manageable.
With 12-inch wheels, front and rear suspension, three selectable speed settings and a removable 36V battery, the SX-E400 offers considerably more of a dirt-bike experience than a basic electric balance bike.
However, it is still aimed at young and developing riders rather than children who need the additional size and performance of the SX-E500 or SX-E700.
In this RFN Warrior SX-E400 review, we look at its performance, rider sizing, battery life, ride quality, strengths, drawbacks and how it compares with the larger RFN Warrior models.
RFN Warrior SX-E400 Review: Our Verdict
A Proper First Electric Dirt Bike
The SX-E400 is one of the strongest options for a younger child who wants a proper electric motocross-style bike rather than another lightweight balance bike.
Its three speed settings allow parents to introduce the performance gradually, while the suspension, wide tyres and motocross-style chassis make it feel far more substantial than most entry-level kids electric bikes.
Its main limitation is that taller or more confident riders may quickly need the additional size and braking performance of the SX-E500. For the correct rider, though, the SX-E400 is an excellent introduction to electric off-road riding.
Best Feature
Three speed settings that allow the bike’s performance to increase with the rider.
Best Rider
A confident young rider who already understands balance and basic braking.
Main Limitation
It may feel too small for taller children near the upper end of the recommended age range.
Overall Position
The most manageable entry point into the RFN Warrior Kids motocross-style range.
RFN Warrior SX-E400 Pros and Cons
What We Like
- Proper miniature motocross styling
- Manageable dimensions for younger riders
- Three parental speed settings
- Front and rear suspension
- Removable lithium battery
- Wide tyres for grass and dirt
- Lanyard-style safety power cut-off
- Good progression from a balance bike
- Quiet electric motor
- Simple direct-drive chain system
Points to Consider
- Rear disc brake only
- Heavier than a basic electric balance bike
- Highest speed mode requires confident supervision
- May be outgrown by taller riders
- Not suitable for public-road use
- Final assembly and safety checks are required
Who Is the RFN Warrior SX-E400 For?
The RFN Warrior SX-E400 is designed for riders aged around 3–6 years old and approximately 90–110cm tall. The maximum recommended rider weight is approximately 50kg.
Age should not be used on its own when choosing a bike. A taller five-year-old may already be better suited to the SX-E500, while a smaller or more cautious six-year-old may still feel comfortable on the SX-E400.
The rider should ideally already be able to balance confidently on two wheels and understand simple instructions about accelerating, braking and stopping.
SX-E400 rider guide
- Age guide: around 3–6 years
- Height guide: approximately 90–110cm
- Maximum rider weight: approximately 50kg
- Best rider type: beginner to developing young rider
- Useful previous experience: balance bike, bicycle or smaller electric bike
- Best terrain: grass, dirt, fields and light private off-road areas
- Next step: RFN Warrior SX-E500
Is the SX-E400 suitable for a complete beginner?
It can be, but it depends on the child.
The SX-E400 is more substantial than a lightweight electric balance bike and weighs approximately 18kg. A very small or completely inexperienced rider may find that weight and motocross-style riding position more difficult to manage.
A confident child who already balances comfortably on a bicycle or balance bike can usually begin in the lowest speed setting and progress gradually.
RFN Warrior SX-E400 Key Specifications
| Specification | RFN Warrior SX-E400 |
|---|---|
| Motor | 36V electric motor |
| Rated output | 400W |
| Peak rear-wheel torque | Approximately 26Nm |
| Battery | 36V 5.2Ah removable lithium-ion battery |
| Energy capacity | 187Wh |
| Speed settings | Approximately 5mph, 7.5mph and 15.5mph |
| Maximum range | Up to approximately 11 miles in Eco mode |
| Claimed Eco ride time | Up to approximately two hours in suitable conditions |
| Full charging time | Approximately 160 minutes |
| 80% charging time | Approximately 120 minutes |
| Brake | 140mm rear disc brake |
| Suspension | Front suspension and rear mono shock |
| Ground clearance | Approximately 125mm |
| Wheels | 12-inch front and rear |
| Bike weight | Approximately 18kg |
| Maximum rider weight | Approximately 50kg |
Speed, range and riding time will vary with rider weight, terrain, temperature, speed mode and riding style.
Design and Build Quality
The first thing most riders notice about the SX-E400 is that it looks like a proper miniature motocross bike.
It has motocross-style bodywork, footrests, suspension and wide tyres rather than the flat saddle and bicycle-style frame commonly found on electric balance bikes.
This makes the SX-E400 more appealing to children who want a bike that resembles the motocross machines ridden by older children and adults.
The frame is designed to provide a stable and planted platform, while the wide swingarm and tyres help give the bike useful grip across grass, dirt, sand and light mud.
Does it feel heavy?
At approximately 18kg, the SX-E400 is heavier than most small electric balance bikes.
That extra weight helps it feel more stable while moving, but it can make the bike harder for a very small rider to pick up, push around or support at a standstill.
This is why rider height and strength matter just as much as age when choosing between the SX-E400 and SX-E500.
Motor Performance and Riding Experience
The RFN Warrior SX-E400 uses a quiet 36V electric motor that delivers smooth, predictable power rather than an aggressive burst of acceleration.
That makes it much easier for younger riders to build confidence. Instead of feeling intimidating, the throttle response is progressive and easy to control, particularly in the lower speed settings.
The bike feels noticeably more capable than a typical electric balance bike, yet it never feels like too much machine for the rider it has been designed for.
For parents, this is probably one of the SX-E400's biggest strengths. It introduces children to throttle control, standing on the footpegs and proper riding position without overwhelming them.
Three Speed Modes Reviewed
One of the standout features of the SX-E400 is the ability to limit the bike's performance as the rider develops.
Speed Modes
- Mode 1: Approximately 5mph
- Mode 2: Approximately 7.5mph
- Mode 3: Approximately 15.5mph
The lowest setting is ideal for learning basic throttle control and stopping safely.
The middle setting is where most young riders will spend the majority of their time, while the highest mode gives enough performance to keep the bike exciting once confidence grows.
This gradual progression is one of the reasons the SX-E400 works so well as a first electric dirt bike.
Battery Life Review
The removable 36V 5.2Ah lithium battery is another highlight.
Rather than having to move the entire bike indoors, the battery can simply be removed for charging.
- 36V 5.2Ah lithium battery
- Removable battery pack
- Up to approximately 11 miles of range
- Up to around two hours riding in Eco mode
- Approximately 2½ hours to recharge
Real-world riding time depends heavily on terrain, rider weight, speed setting and how aggressively the bike is ridden.
Children constantly using full throttle on grass or hills will naturally achieve less riding time than someone riding gently on flatter ground.
Suspension and Ride Quality
Compared with a basic electric balance bike, the SX-E400 feels far more planted over uneven terrain.
The combination of front suspension and the rear mono shock helps absorb bumps, making the bike noticeably more comfortable across grass, woodland tracks and light off-road terrain.
The suspension is designed for younger recreational riders rather than competitive motocross use, but it performs very well for its intended purpose.
It gives the bike a genuine mini motocross feel without becoming difficult for smaller riders to manage.
Braking Performance
The SX-E400 uses a rear disc brake, giving consistent stopping performance for younger riders.
The braking system is simple, predictable and easy to learn, making it appropriate for children who are still developing coordination and confidence.
Older or faster riders may eventually benefit from the upgraded braking systems found on the SX-E500 and SX-E700, but for the intended rider the SX-E400 performs well.
How Does the SX-E400 Ride Off Road?
The SX-E400 has been designed primarily for private off-road riding.
Its wide tyres and suspension allow it to cope comfortably with:
- Grass fields
- Dirt tracks
- Light woodland trails
- Private paddocks
- Uneven garden terrain
It is much happier on natural surfaces than many electric balance bikes, making it an excellent stepping stone towards larger electric motocross bikes.
Like any children's off-road bike, it performs best where the rider has plenty of room and suitable supervision.
RFN Warrior SX-E400 vs SX-E500
The biggest question most parents ask is whether they should buy the SX-E400 or move straight to the SX-E500.
| Feature | SX-E400 | SX-E500 |
|---|---|---|
| Best For | Smaller, younger riders | Growing riders wanting more room |
| Power | 400W | 500W |
| Top Speed | Approximately 15.5mph | Approximately 18.5mph |
| Wheels | 12-inch | 14-inch |
| Best Rider | First electric dirt bike | Confident developing rider |
The SX-E400 is easier for younger children to manage, while the SX-E500 offers more room to grow and feels like a bigger motocross bike.
If your child is towards the upper end of the SX-E400 height guide or already rides confidently, the SX-E500 may ultimately prove to be the better long-term investment.
Read our complete RFN Warrior SX-E400 vs SX-E500 comparison before deciding.
What Could Be Better?
No bike is perfect, and there are a few things worth considering before buying the SX-E400.
- Taller children may outgrow it fairly quickly.
- It uses a simpler braking system than the larger SX-E500 and SX-E700.
- It feels heavier than a lightweight electric balance bike when manoeuvring at a standstill.
- Very experienced riders may quickly want the additional speed and capability of the SX-E500.
None of these are major drawbacks—they simply reflect the fact that the SX-E400 is designed to be the smallest and most manageable bike in the RFN Warrior Kids range.
Would I Recommend It?
Yes — For the Right Rider
If your child is the correct size and is ready to move beyond a balance bike, the SX-E400 is one of the best entry points into electric motocross riding.
It offers enough performance to stay exciting while remaining approachable for younger riders, and the three speed settings allow the bike to grow with them as confidence develops.
Shop RFN Warrior SX-E400Fast UK Delivery and Straightforward Setup
The RFN Warrior SX-E400 can be ordered online for fast UK delivery. The bike is supplied securely packaged and will require final assembly and safety checks before its first ride.
Garland Powersports operates as an online-only specialist retailer, with bikes held boxed within our UK warehouse network and prepared for dispatch.
- Fast UK delivery available
- Supplied securely packaged
- Some final assembly required
- Brakes, controls, wheels and fasteners should be checked before riding
- The battery should be charged correctly before first use
- Adult supervision and suitable protective equipment are essential
Before the first ride, an adult should make sure the handlebars, controls, rear brake, wheels and all visible fasteners are correctly fitted and secure.
Is the RFN Warrior SX-E400 Worth Buying?
The RFN Warrior SX-E400 is worth buying if your child wants a proper electric motocross-style bike but still needs something smaller and more manageable than the SX-E500.
Its biggest strengths are the three selectable speed settings, front and rear suspension, removable battery and genuine mini dirt-bike design.
It gives younger riders more of a motocross experience than a traditional electric balance bike while still allowing parents to introduce the performance gradually.
The main thing to check before buying is rider size. If your child is already close to the upper end of the height guide or is a very confident rider, the SX-E500 may offer better long-term value.
My Take as a British Motocross Rider
The SX-E400 is a really good first step for a younger rider who wants something that looks and feels like a proper motocross bike.
What I like most is that it does not force the rider to use all of the performance straight away. The lower modes let them learn throttle control, braking and body position before progressing.
It is more substantial than a basic balance bike, so I would still make sure the child is confident on two wheels and physically big enough to manage the weight.
For the right-sized rider, though, the SX-E400 is a strong introduction to electric off-road riding and a sensible first model in the RFN Warrior range.
RFN Warrior SX-E400 FAQs
What age is the RFN Warrior SX-E400 for?
The RFN Warrior SX-E400 is generally aimed at riders aged around 3–6 years old. Height, confidence and previous experience should also be considered.
What height rider is the SX-E400 for?
The SX-E400 is generally suited to riders approximately 90–110cm tall. This should be treated as a guide rather than a strict rule.
How fast does the RFN Warrior SX-E400 go?
The SX-E400 has three speed settings of approximately 5mph, 7.5mph and 15.5mph.
Can parents restrict the speed?
Yes. The three selectable speed settings allow parents to limit the available performance while the rider is learning and increase it as confidence improves.
How long does the SX-E400 battery last?
The bike can provide up to approximately 11 miles of range in suitable conditions, with longer ride times possible in the lowest mode. Actual performance depends on terrain, rider weight, temperature and riding style.
Is the SX-E400 battery removable?
Yes. The SX-E400 uses a removable 36V 5.2Ah lithium-ion battery, making it easier to charge away from the bike.
How long does the SX-E400 take to charge?
A full charge typically takes around 2.5–3 hours, depending on the battery condition and charger used.
Does the SX-E400 have suspension?
Yes. It has front suspension and a rear mono shock to help improve control and comfort over grass, dirt and uneven private off-road terrain.
Does the SX-E400 have front and rear brakes?
No. The SX-E400 uses a rear disc brake. Riders should become fully comfortable with braking before progressing into the higher speed settings.
Is the SX-E400 suitable for beginners?
Yes, it can suit a beginner who already balances confidently on two wheels and can follow basic instructions. A very small or cautious child may still find a lighter electric balance bike easier to manage.
Is the SX-E400 better than an electric balance bike?
It is not automatically better, but it offers a more substantial motocross-style experience. A traditional electric balance bike is usually lighter and simpler, while the SX-E400 adds suspension, footpegs and a more planted dirt-bike chassis.
Should I buy the SX-E400 or SX-E500?
Choose the SX-E400 for a smaller or younger rider who needs the most manageable RFN Warrior model. Choose the SX-E500 for a taller or more confident rider who wants larger wheels, more speed and more room to grow.
Read our full RFN Warrior SX-E400 vs SX-E500 comparison before deciding.
Is the SX-E400 road legal?
No. The RFN Warrior SX-E400 is intended for private land and suitable off-road riding areas with the landowner’s permission. It is not designed for public-road use.
Where can the SX-E400 be ridden?
It is suitable for private gardens, fields, dirt tracks and light off-road areas where permission has been granted.
Do riders need protective equipment?
Yes. Riders should wear a correctly fitting helmet, gloves, suitable boots and protective clothing. Adult supervision is essential.
Do you offer fast UK delivery?
Yes. Garland Powersports offers fast UK delivery on RFN Warrior SX-E400 bikes when stock is available.
Explore the RFN Warrior Kids Range
If you are still deciding which model is right, our RFN Warrior Kids range explained guide compares the SX-E400, SX-E500 and SX-E700 in more detail.
RFN Warrior SX-E400
The smallest and most manageable option for younger riders entering the RFN Warrior range.
Shop SX-E400RFN Warrior SX-E500
The all-round step-up option for growing riders who need larger wheels and more performance.
Shop SX-E500RFN Warrior SX-E700
The highest-performance model for confident riders who are ready for more speed and stronger components.
Shop SX-E700Final Verdict: Should You Buy the RFN Warrior SX-E400?
The RFN Warrior SX-E400 is a strong choice for younger riders who want their first proper electric dirt bike.
It combines manageable dimensions, adjustable speed settings, suspension and a removable battery in a bike that looks and feels much more like a miniature motocross machine than a standard electric balance bike.
For a child around 90–110cm tall who already balances confidently, it offers a very good introduction to throttle control, braking and off-road riding.
Taller or more experienced children may get better long-term value from the SX-E500, but for the correct rider the SX-E400 does exactly what it is designed to do.