Quick answer: Choose the RFN Warrior SX-E400 for younger riders around 90–110cm tall, the SX-E500 for developing riders around 100–120cm tall, and the SX-E700 for confident riders of a similar physical size who are ready for more performance.
Most important: height and physical fit narrow down the right bike, but rider confidence and experience should decide between the SX-E500 and SX-E700.
RFN Warrior Size Guide
Choosing the correct RFN Warrior size is not simply a case of selecting a bike from the rider’s age.
The RFN Warrior Kids range includes the compact SX-E400, the all-round SX-E500 and the higher-performance SX-E700.
The SX-E400 is physically smaller, with a lower seat and 12-inch wheels. The SX-E500 and SX-E700 share similar overall rider sizing, but they are intended for different confidence and experience levels.
This means the right choice depends on four main factors:
- Rider height and inside leg
- Ability to reach the controls and support the bike
- Previous two-wheel and throttle experience
- How much performance the rider can safely manage
This RFN Warrior size guide compares the SX-E400, SX-E500 and SX-E700 by seat height, rider height, age, weight, wheel size and ability level.
RFN Warrior Size Chart
| Model | Age Guide | Rider Height | Seat Height | Wheels | Bike Weight | Best Rider |
|---|---|---|---|---|---|---|
| RFN SX-E400 | Around 3–6 years | Approximately 90–110cm | Approximately 460mm | 12-inch | Approximately 18kg | Younger beginner or developing rider |
| RFN SX-E500 | Around 4–7 years | Approximately 100–120cm | Approximately 490mm | 14-inch | Approximately 19kg | Confident beginner or developing rider |
| RFN SX-E700 | Around 4–8 years | Approximately 100–120cm | Approximately 490mm | 14-inch | Approximately 20kg | Confident or experienced young rider |
Age and height figures should be treated as general guides. Individual rider proportions, strength, confidence and experience can change which bike is most suitable.
Which RFN Warrior Should I Choose?
Choose the SX-E400
For a younger or smaller rider who needs the lowest seat height, smallest chassis and most manageable beginner speed.
Best fit: approximately 90–110cm tall.
Choose the SX-E500
For a growing rider who already balances confidently and wants a proper 14-inch electric dirt bike with manageable performance.
Best fit: approximately 100–120cm tall.
Choose the SX-E700
For a rider who physically fits the SX-E500 size but already has enough experience for more power, range and hydraulic brakes.
Best fit: approximately 100–120cm tall and already confident.
RFN Warrior Size by Rider Height
Height is normally a better starting point than age when choosing a kids electric bike.
Children of the same age can vary significantly in height, strength and riding ability.
| Rider Height | Likely RFN Model | What to Check |
|---|---|---|
| Below 90cm | Likely below the RFN Warrior range | A lighter electric balance bike may be easier to manage |
| 90–100cm | SX-E400 | Check brake reach, balance and ability to support 18kg |
| 100–110cm | SX-E400 or SX-E500 | Choose according to confidence, strength and previous experience |
| 110–120cm | SX-E500 or SX-E700 | Choose according to ability and required performance |
| Above 120cm | May need a larger youth model | Check knee room, standing space and overall chassis size |
RFN Warrior Size by Age
Age can help narrow down the options, but it should not replace physical sizing and ability checks.
| Rider Age | Likely RFN Model | Important Consideration |
|---|---|---|
| 3 years | SX-E400 for a confident rider | Many small three-year-olds may still need a lighter bike |
| 4 years | SX-E400 or SX-E500 | The SX-E500 suits taller and more confident riders |
| 5 years | SX-E400 or SX-E500 | Compare height, confidence and likely growth |
| 6 years | SX-E500 or SX-E700 | Choose the SX-E700 only when ability supports the extra performance |
| 7 years | SX-E500 or SX-E700 | Check physical fit at the upper end of the height guide |
| 8 years | SX-E700 if still within the size guide | A taller eight-year-old may need a physically larger youth bike |
RFN Warrior 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 approximately 30mm lower at the seat than the SX-E500 and SX-E700.
The SX-E500 and SX-E700 share similar physical sizing, so their seat height does not decide which one is right. Rider ability does.
How to Measure the Rider
Before choosing an RFN Warrior, measure the child’s overall height and inside leg.
Measure overall height
- Ask the child to stand upright against a wall.
- Make sure they are not wearing a helmet.
- Measure from the floor to the top of their head.
Measure the inside leg
- Ask the child to stand naturally with their back against a wall.
- They should wear the boots or footwear they will ride in.
- Place a book firmly between their legs to simulate the seat.
- Measure from the floor to the upper edge of the book.
RFN mainly provides overall rider-height and seat-height guidance rather than strict minimum inside-leg requirements.
The inside-leg measurement should therefore be used alongside a practical fit check rather than as the only deciding factor.
Does the Rider Need Both Feet Flat?
No. The rider does not necessarily need both feet completely flat on the floor.
They should, however, be able to support the bike securely using the balls of both feet or one foot firmly on the ground.
A very young beginner will normally feel more confident with greater ground contact.
The rider should not be balancing on the very tips of their toes or relying entirely on an adult whenever the bike stops.
A Correct RFN Warrior Fit
- The rider reaches the handlebars naturally
- They can turn the bars fully in both directions
- They can reach and operate the brake lever or levers
- At least one foot supports the bike securely
- Their knees are not excessively cramped
- They can stand naturally on the footrests
- They can hold the bike upright without excessive help
Bike Weight Matters as Much as Seat Height
A child may be tall enough for an RFN Warrior but still struggle with its weight.
| Model | Approximate Weight | What the Rider Must Manage |
|---|---|---|
| SX-E400 | 18kg | Support the smallest chassis and operate the rear brake |
| SX-E500 | 19kg | Support a larger chassis and use front and rear brakes |
| SX-E700 | 20kg | Manage stronger performance and hydraulic brake controls |
The rider should be able to hold the bike upright, turn the handlebars at low speed and support the bike when stopping.
If they cannot manage those tasks while the power is switched off, the bike is likely too large or heavy.
How Rider Experience Changes the Correct Size
Physical sizing narrows down the possible models, but riding experience often makes the final decision.
Complete beginner
A complete beginner should normally start with the most manageable bike that fits physically.
For a rider around 90–110cm tall, this will usually be the SX-E400.
For a rider around 100–120cm tall, the SX-E500 will normally be more suitable than the SX-E700.
Confident bicycle or balance-bike rider
A confident child who already balances and brakes well may move directly onto the SX-E400 or SX-E500, depending on height.
Experienced electric-bike rider
A rider who already understands a twist throttle, front and rear braking and controlled stopping may be ready for the SX-E700 when their physical size also fits.
SX-E400 or SX-E500?
The SX-E400 and SX-E500 overlap for riders around 100–110cm tall.
Choose the SX-E400 when the rider:
- Is younger, smaller or more cautious
- Needs the lower 460mm seat
- Would benefit from the 5mph beginner mode
- Is still developing confidence
- Needs the smallest and most manageable chassis
Choose the SX-E500 when the rider:
- Already balances confidently
- Can manage separate front and rear brakes
- Is comfortable beginning around 9.5mph
- Would benefit from 14-inch wheels
- Needs more space and room to grow
Read our full RFN Warrior SX-E400 vs SX-E500 comparison.
SX-E500 or SX-E700?
The SX-E500 and SX-E700 share similar seat heights, wheel sizes and rider-height guidance.
Choose the SX-E500 when the rider:
- Is a confident beginner or developing rider
- Still needs manageable acceleration
- Is learning front and rear braking
- Does not need the maximum RFN performance
- Would benefit from the best all-round option
Choose the SX-E700 when the rider:
- Already has throttle-controlled riding experience
- Uses front and rear brakes correctly
- Stops consistently and on command
- Is ready for stronger acceleration
- Will benefit from a larger battery and hydraulic brakes
Read our full RFN Warrior SX-E500 vs SX-E700 MX comparison.
Does SX-E700 MX or SM Change the Rider Size?
No. The SX-E700 MX and SX-E700 SM use the same general seat height, rider-height and weight guidance.
The difference is the tyre setup and intended riding surface.
- SX-E700 MX: grass, dirt, fields and loose off-road ground
- SX-E700 SM: smooth, hard and prepared private surfaces
Choose the version according to terrain rather than rider dimensions.
Read our RFN Warrior SX-E700 MX vs SX-E700 SM comparison.
Signs the Bike Is the Correct Size
The chosen RFN Warrior is likely to fit correctly when the rider can:
- Sit naturally without stretching forwards
- Reach the throttle and brake controls
- Turn the handlebars fully
- Support the bike securely when stopped
- Stand comfortably on the footrests
- Hold the bike upright while stationary
- Use the lowest speed mode calmly
- Stop safely and on command
Signs the Bike Is Too Large
The bike may be too large or advanced if the rider:
- Cannot reach the floor securely
- Cannot reach the brake lever or levers
- Struggles to turn the handlebars
- Cannot support the bike when stationary
- Looks stretched towards the controls
- Is frightened by the lowest speed mode
- Does not yet have reliable two-wheel balance
Choosing a smaller model will usually improve confidence and allow the rider to progress more safely.
Signs the Bike Is Too Small
The bike may be too small if the rider:
- Looks cramped around the handlebars
- Has excessively bent knees
- Has limited room when standing
- Is above the recommended height range
- Has physically outgrown the wheel and chassis size
- Already controls the maximum setting comfortably
Do not automatically move to a more powerful model when the rider needs a physically larger bike. The next RFN model may offer more performance without a major increase in physical dimensions.
How to Check the Fit Before Riding
Complete a stationary fit check before the bike is powered on.
- Place the bike on flat and level ground.
- Make sure the power is 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 bars 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 ride should take place in the lowest mode within a large, flat and controlled private area.
My Take as a British Motocross Rider
The main thing I would avoid is automatically choosing the highest RFN model because it sounds like the rider will get more use from it.
The SX-E400 is physically smaller, so that choice is mainly about rider size. The SX-E500 and SX-E700 are different because their sizing is very similar.
For those two bikes, the rider’s ability matters more than their height. The SX-E500 is the right bike while they are developing, and the SX-E700 is the right bike once they already have good throttle and braking control.
Choose the bike the child can control confidently now, rather than the most powerful model they might eventually grow into.
RFN Warrior Size Guide FAQs
What is the smallest RFN Warrior?
The SX-E400 is the smallest model, with a 460mm seat height, 12-inch wheels and a rider-height guide of approximately 90–110cm.
What is the RFN SX-E400 rider height?
The SX-E400 is generally suited to riders around 90–110cm tall.
What is the RFN SX-E500 rider height?
The SX-E500 is generally suited to riders around 100–120cm tall.
What is the RFN SX-E700 rider height?
The SX-E700 is generally suited to confident riders around 100–120cm tall.
What is the SX-E400 seat height?
The approximate SX-E400 seat height is 460mm.
What is the SX-E500 seat height?
The approximate SX-E500 seat height is 490mm.
What is the SX-E700 seat height?
The approximate SX-E700 seat height is 490mm.
Are the SX-E500 and SX-E700 the same size?
They have similar seat heights, wheel sizes and rider-height guidance. The SX-E700 offers stronger performance, a larger battery and hydraulic brakes.
Which RFN Warrior is best for a beginner?
Choose the model that fits physically and offers manageable performance. The SX-E400 is best for smaller beginners, while the SX-E500 is the better all-round choice for taller developing riders.
Which RFN Warrior is best for an experienced rider?
The SX-E700 is designed for confident riders who already understand throttle control and front and rear braking.
Does the rider need both feet flat?
No, but they should be able to support the bike securely and remain stable when stopping.
Can I choose an RFN Warrior from age alone?
No. Height, inside leg, arm reach, strength, confidence and previous experience should all be considered.
What is the maximum rider weight?
The core RFN Warrior Kids models generally have a maximum recommended rider weight of approximately 50kg.
Which model comes after the SX-E400?
The SX-E500 is the natural step up for a taller or more confident rider.
Which model comes after the SX-E500?
The SX-E700 is the next performance step for a rider who already has good throttle and braking control.
Explore the RFN Warrior Range
RFN Warrior SX-E400
460mm seat height and 12-inch wheels for riders around 90–110cm tall.
Shop SX-E400RFN Warrior SX-E500
490mm seat height and 14-inch wheels for developing riders around 100–120cm tall.
Shop SX-E500RFN Warrior SX-E700
Similar physical sizing to the SX-E500 but designed for confident and experienced riders.
Shop SX-E700Choose the Correct RFN Warrior Size
Choose the SX-E400 for a younger rider around 90–110cm tall who needs the smallest and most manageable RFN Warrior.
Choose the SX-E500 for a growing rider around 100–120cm tall who wants the best balance of size, control and progression.
Choose the SX-E700 for a rider of a similar physical size who already has the experience required for stronger performance and hydraulic brakes.
Browse the RFN Warrior range online with Garland Powersports and compare each model before making your final decision.