Quick answer: Choose the RFN Warrior SX-E400 for riders around 90–110cm tall. Choose the SX-E500 for developing riders around 100–120cm tall. Choose the SX-E700 for confident riders of a similar height who are ready for stronger performance.
Most important: height identifies which bikes may physically fit, but confidence and previous experience should decide between the SX-E500 and SX-E700.
Best RFN Warrior by Height
Choosing the best RFN Warrior by height is more reliable than choosing from age alone.
Children of the same age can differ significantly in overall height, inside-leg measurement, strength and riding experience.
The RFN Warrior Kids range includes three core models:
- RFN Warrior SX-E400: approximately 90–110cm rider height
- RFN Warrior SX-E500: approximately 100–120cm rider height
- RFN Warrior SX-E700: approximately 100–120cm rider height for confident riders
The SX-E400 is physically smaller, with a 460mm seat height and 12-inch wheels.
The SX-E500 and SX-E700 both have an approximate 490mm seat height and 14-inch wheels. Their physical sizing is similar, so the final choice between them depends mainly on rider ability.
This guide explains which RFN Warrior is best for riders at different heights and what else to check before ordering.
RFN Warrior Height Chart
| Model | Rider Height | Seat Height | Wheel Size | Bike Weight | Best Rider |
|---|---|---|---|---|---|
| RFN Warrior SX-E400 | Approximately 90–110cm | Approximately 460mm | 12-inch | Approximately 18kg | Younger, smaller or developing rider |
| RFN Warrior SX-E500 | Approximately 100–120cm | Approximately 490mm | 14-inch | Approximately 19kg | Confident beginner or developing rider |
| RFN Warrior SX-E700 | Approximately 100–120cm | Approximately 490mm | 14-inch | Approximately 20kg | Confident or experienced young rider |
These figures should be treated as general guides. Inside leg, arm reach, strength and rider confidence can change which model is most suitable.
Which RFN Warrior Is Best for Each Height?
Our Height-Based Recommendation
Below 90cm: likely below the RFN Warrior range.
90–100cm: SX-E400.
100–110cm: SX-E400 or SX-E500, depending on confidence and experience.
110–120cm: SX-E500 for developing riders or SX-E700 for experienced riders.
Above 120cm: the core RFN Warrior Kids range may feel physically small, so consider a larger youth electric bike.
Best RFN Warrior for Riders Below 90cm
A rider below approximately 90cm tall is likely to be too small for the core RFN Warrior Kids range.
Even the smallest SX-E400 has:
- An approximate 460mm seat height
- A bike weight of around 18kg
- A motocross-style chassis
- A twist throttle and rear disc brake
A child below the recommended height may struggle to reach the ground, operate the brake or support the bike safely.
For riders below 90cm, a lighter electric balance bike will normally be easier to manage and more suitable for building confidence.
Best choice below 90cm
RFN recommendation: likely below the RFN Warrior size range.
Alternative: a lighter and lower electric balance bike.
Best RFN Warrior for Riders 90–100cm Tall
The RFN Warrior SX-E400 is normally the best model for riders around 90–100cm tall.
It is the smallest RFN Warrior and uses:
- A 460mm seat height
- 12-inch front and rear wheels
- An approximate 18kg chassis
- A 5mph lowest speed mode
- A rear disc brake
This makes the SX-E400 easier to manage than the taller SX-E500 and SX-E700.
The rider should still be able to reach the handlebars and brake lever, support the bike when stationary and balance confidently on two wheels.
Best choice at 90–100cm
Recommended model: SX-E400
Best rider: younger or smaller child with reliable balance
Main check: ability to support the 18kg bike and reach the rear brake.
Best RFN Warrior for Riders 100–105cm Tall
Riders around 100–105cm sit within the crossover between the SX-E400 and SX-E500.
Choose the SX-E400 when the rider:
- Is younger, smaller or cautious
- Is learning throttle control
- Would benefit from the slower 5mph setting
- Needs the lower 460mm seat
- Has limited electric-bike experience
Consider the SX-E500 when the rider:
- Already balances confidently
- Can reach and use both brake levers
- Can manage a 19kg bike
- Is comfortable with a 9.5mph lowest mode
- Would benefit from a larger 14-inch chassis
For most cautious or first-time riders at this height, the SX-E400 remains the safer starting point.
Best RFN Warrior for Riders 105–110cm Tall
At approximately 105–110cm tall, either the SX-E400 or SX-E500 may fit physically.
This is the main overlap point in the RFN range.
| Choose SX-E400 When | Choose SX-E500 When |
|---|---|
| The rider is cautious or inexperienced | The rider already balances confidently |
| They need a 5mph beginner mode | They can manage a 9.5mph lowest mode |
| They need the lower 460mm seat | They fit the 490mm seat comfortably |
| They are still developing basic control | They can use separate front and rear brakes |
Choose the SX-E400 for easier learning and the SX-E500 for additional room to progress.
Read our full RFN Warrior SX-E400 vs SX-E500 comparison.
Best RFN Warrior for Riders 110–115cm Tall
The SX-E500 will normally be the best all-round RFN Warrior for riders around 110–115cm tall.
At this height, the SX-E400 may begin to feel physically compact, particularly when the rider stands on the footrests.
The SX-E500 provides:
- A 490mm seat height
- 14-inch wheels
- Front and rear disc brakes
- More room around the handlebars
- Three speed settings up to approximately 18.5mph
The SX-E700 may also fit physically, but it should only be selected when the rider already has enough experience for its stronger performance.
Best choice at 110–115cm
Default recommendation: SX-E500
Experienced rider: consider SX-E700
Main deciding factor: throttle and braking ability.
Best RFN Warrior for Riders 115–120cm Tall
Riders around 115–120cm tall are likely to fit both the SX-E500 and SX-E700 physically.
The bikes use similar seat heights and wheel sizes, so height does not clearly separate them.
Choose the SX-E500 when the rider:
- Is a beginner or developing rider
- Still needs manageable acceleration
- Is learning to use front and rear brakes
- Has limited twist-throttle experience
- Wants the best all-round RFN Warrior
Choose the SX-E700 when the rider:
- Already rides an electric bike confidently
- Accelerates smoothly
- Uses both brakes correctly
- Stops calmly and consistently
- Will benefit from the larger battery
- Is ready for hydraulic braking and stronger performance
Best choice at 115–120cm
Developing rider: SX-E500
Experienced rider: SX-E700
Important: the SX-E700 is more powerful, not significantly larger.
Read our full RFN Warrior SX-E500 vs SX-E700 MX comparison.
Best RFN Warrior for Riders Above 120cm Tall
A rider above approximately 120cm may begin to find the core RFN Warrior Kids range physically compact.
The SX-E500 and SX-E700 share a similar 490mm seat height and 14-inch chassis.
Moving from the SX-E500 to the SX-E700 increases power, battery capacity and braking performance, but it does not create a major increase in physical size.
Signs the rider may need a larger youth bike include:
- Knees appearing cramped around the handlebars
- Limited room while standing on the footrests
- Excessively bent legs when seated
- Restricted handlebar movement
- The rider already looking physically large on other 14-inch bikes
Do not choose the SX-E700 purely because the child is taller than the SX-E500 guide. A physically larger bike may be the better next step.
RFN Warrior by Height: Summary Table
| Rider Height | Best Starting Model | Alternative | Main Deciding Factor |
|---|---|---|---|
| Below 90cm | Likely below RFN range | Electric balance bike | Ability to manage seat height and bike weight |
| 90–100cm | SX-E400 | None for most riders | Brake reach and strength |
| 100–105cm | SX-E400 | SX-E500 | Confidence and ability to manage 9.5mph |
| 105–110cm | SX-E400 or SX-E500 | Depends on experience | Physical fit and riding confidence |
| 110–115cm | SX-E500 | SX-E700 | Rider experience |
| 115–120cm | SX-E500 | SX-E700 | Developing or experienced rider |
| Above 120cm | Consider larger youth bike | SX-E700 only if physical fit remains suitable | Knee room and overall chassis size |
Why Height Is Better Than Age
Age ranges are useful, but rider height gives a clearer indication of physical fit.
Two six-year-olds may differ by more than 15cm in height and may require completely different bikes.
A shorter six-year-old may still fit the SX-E400, while a taller and experienced six-year-old may be ready for the SX-E700.
Height helps assess:
- Whether the rider can reach the ground
- Whether their knees will be cramped
- Whether they can reach the controls
- Whether they have enough standing room
- Whether the chassis offers room for growth
Age should be used as supporting information rather than the final deciding factor.
Inside Leg Matters Too
Overall height does not reveal every rider’s proportions.
Two children who are both 110cm tall may have different leg lengths and arm reach.
To measure the child’s inside leg:
- Ask them to stand upright against a wall.
- Use the boots or footwear they will ride in.
- Place a book firmly between their legs to represent the bike seat.
- Measure from the floor to the top edge of the book.
The rider does not need an inside-leg measurement equal to the complete seat height.
Suspension movement and the width of the bike affect how easily the child can reach the ground.
The rider should still be able to support the bike securely when stopping.
Does the Rider Need Both Feet Flat?
No. Both feet do not necessarily need to be completely flat on the floor.
A rider may manage the bike safely when they can:
- Place the balls of both feet on the ground
- Place one foot firmly down
- Keep the bike balanced while stationary
- Stop without relying entirely on an adult
Younger beginners generally benefit from more ground contact because it improves confidence.
A rider should not be balancing on the very tips of their toes or struggling to stop the bike from leaning.
Seat Height Comparison
| Model | Seat Height | Approximate Inches | Rider Height |
|---|---|---|---|
| SX-E400 | Approximately 460mm | Approximately 18.1 inches | Approximately 90–110cm |
| SX-E500 | Approximately 490mm | Approximately 19.3 inches | Approximately 100–120cm |
| SX-E700 | Approximately 490mm | Approximately 19.3 inches | Approximately 100–120cm |
The SX-E400 is physically lower and more compact.
The SX-E500 and SX-E700 have similar physical dimensions, so rider ability becomes the main difference between them.
Bike Weight and Rider Strength
Height does not automatically mean the child is strong enough to manage the bike.
| Model | Approximate Weight | Rider Requirement |
|---|---|---|
| SX-E400 | 18kg | Support the bike and operate the rear brake |
| SX-E500 | 19kg | Manage a larger chassis and front and rear brakes |
| SX-E700 | 20kg | Manage stronger performance and hydraulic controls |
The rider should be able to hold the bike upright with the motor switched off before attempting to ride.
SX-E400 or SX-E500 by Height?
The main physical crossover is around 100–110cm.
Choose the SX-E400 when the rider:
- Is closer to 100cm
- Needs the lower seat
- Is new to twist throttles
- Needs a 5mph learning mode
- Is smaller or more cautious
Choose the SX-E500 when the rider:
- Is closer to 110cm or taller
- Already balances confidently
- Can operate both brakes
- Fits the larger 14-inch chassis comfortably
- Needs more physical room to progress
SX-E500 or SX-E700 by Height?
Height does not separate the SX-E500 and SX-E700 because both suit approximately 100–120cm riders.
Choose the SX-E500 for a rider who is still developing.
Choose the SX-E700 for a rider who already has:
- Electric-bike experience
- Smooth throttle control
- Good front and rear braking technique
- Reliable controlled stopping
- Enough experience for stronger acceleration
The SX-E700 is a performance upgrade rather than a meaningful physical-size upgrade.
Does SX-E700 MX or SM Affect Rider Height?
No. The SX-E700 MX and SX-E700 SM use the same general rider-height and seat-height guidance.
The difference is the type of tyre:
- SX-E700 MX: grass, dirt, fields and loose off-road terrain
- SX-E700 SM: smooth, hard and prepared private surfaces
Choose the version according to riding terrain rather than rider height.
Read our RFN Warrior SX-E700 MX vs SX-E700 SM comparison.
Signs the Bike Fits Correctly
The selected RFN Warrior is likely to fit correctly when the rider can:
- Sit naturally without stretching forwards
- Reach the throttle and brakes comfortably
- Turn the handlebars fully
- Support the bike with at least one foot
- Stand naturally on the footrests
- Hold the bike upright when stationary
- Control the lowest speed mode calmly
- Stop safely and on command
Signs the Bike Is Too Large
The bike may be too large when the rider:
- Cannot reach the ground securely
- Cannot operate the brake lever or levers
- Struggles to turn the handlebars
- Cannot support the bike when stopped
- Looks stretched towards the controls
- Is intimidated by the lowest speed setting
A smaller bike will normally help the child learn more confidently.
Signs the Bike Is Too Small
The bike may be too small when the rider:
- Looks cramped around the handlebars
- Has excessively bent knees
- Has limited room when standing
- Is above the rider-height guide
- Has physically outgrown the wheel size
- Cannot move naturally around the bike
Remember that moving from the SX-E500 to SX-E700 increases performance more than physical size.
How to Check Rider Fit Before the First Ride
- Place the bike on flat ground with the power switched off.
- Help the child sit naturally on the seat.
- Check that they can reach the handlebars without stretching.
- Confirm they can operate the throttle and brake controls.
- Ask them to turn the handlebars fully in both directions.
- Check how securely they can place their feet down.
- Ask them to hold the bike upright without excessive help.
The first powered session should take place in the lowest speed mode within a large, flat and controlled private area.
My Take as a British Motocross Rider
Height is the best starting point because it tells you whether the child is likely to fit the chassis, but it still does not tell the whole story.
The SX-E400 is clearly the smaller bike. Once the rider is around 100–110cm, you need to look at confidence as well as size.
The SX-E500 and SX-E700 are almost the same physical size, so I would choose between those from ability rather than height.
The correct bike is the one the rider fits physically and can control confidently, not simply the highest model available within their height range.
Best RFN Warrior by Height FAQs
Which RFN Warrior is best for a 90cm rider?
The SX-E400 is the smallest RFN Warrior and is generally the most suitable option from approximately 90cm tall.
Which RFN Warrior is best for a 100cm rider?
The SX-E400 will normally be the best starting point. A confident rider may also compare the SX-E500.
Which RFN Warrior is best for a 105cm rider?
Choose between the SX-E400 and SX-E500 according to rider confidence, strength and previous experience.
Which RFN Warrior is best for a 110cm rider?
The SX-E500 will usually be the best all-round choice. Experienced riders may also compare the SX-E700.
Which RFN Warrior is best for a 115cm rider?
Choose the SX-E500 for a developing rider and the SX-E700 for a confident rider with electric-bike experience.
Which RFN Warrior is best for a 120cm rider?
The SX-E500 or SX-E700 may fit. Choose according to rider ability and check that the chassis still provides enough room.
Which RFN Warrior is best above 120cm?
A larger youth electric bike may be more suitable because the SX-E500 and SX-E700 can begin to feel physically compact.
What rider height is the SX-E400 for?
The SX-E400 is generally suited to riders approximately 90–110cm tall.
What rider height is the SX-E500 for?
The SX-E500 is generally suited to riders approximately 100–120cm tall.
What rider height is the SX-E700 for?
The SX-E700 is generally suited to confident riders approximately 100–120cm tall.
Are the SX-E500 and SX-E700 the same size?
They have similar seat heights, wheels and rider-height guidance. The SX-E700 provides stronger performance and upgraded components.
Does height matter more than age?
Height is usually a better starting point for physical fit, but age, strength and riding experience should also be considered.
Does the rider need both feet flat?
No, but the rider should be able to support the bike securely and remain stable when stopping.
Should I buy the taller or more powerful model for growth?
Only when the rider can already manage it safely. A bike that is too large or powerful can reduce confidence.
What is the maximum rider weight?
The core RFN Warrior Kids models generally have a maximum recommended rider weight of approximately 50kg.
Explore the RFN Warrior Range
Read our complete RFN Warrior Kids range explained guide for more detail.
RFN Warrior SX-E500
The best all-round option for developing riders around 100–120cm tall.
Shop SX-E500Choose the Best RFN Warrior for Your Child’s Height
Choose the SX-E400 for a rider around 90–110cm tall who needs the smallest, lowest and most manageable RFN Warrior.
Choose the SX-E500 for a developing rider around 100–120cm tall who wants the best balance of physical size and manageable performance.
Choose the SX-E700 for a rider of a similar physical size who already has enough experience for more power, range and hydraulic brakes.
Use height to narrow down the options, then confirm the final model using the rider’s inside leg, strength, confidence and previous experience.