Quick answer: The SX-E400 is usually the best RFN Warrior for riders aged around 3–5, the SX-E500 is the strongest all-round choice for many riders aged around 4–8, and the SX-E700 is best for confident riders in a similar age range who already have good throttle and braking control.
Most important: age only narrows down the options. Rider height, physical fit and experience should decide the final model.
Best RFN Warrior by Age
Choosing the best RFN Warrior by age can help narrow down the range, but age should never be used on its own.
The core RFN Warrior Kids range includes three models:
- RFN Warrior SX-E400: the smallest model for younger riders
- RFN Warrior SX-E500: the best all-round choice for developing riders
- RFN Warrior SX-E700: the premium performance option for confident riders
The SX-E400 is physically smaller, with a lower seat, 12-inch wheels and a slower beginner mode.
The SX-E500 and SX-E700 suit a similar broad age and height range. The main difference between them is not rider size: it is the amount of performance and the experience required to manage it.
This guide explains which RFN Warrior is likely to suit riders aged three through eight and when height or ability should override the general age recommendation.
RFN Warrior Age Chart
| Model | Age Guide | Rider Height | Seat Height | Lowest Speed | Best Rider |
|---|---|---|---|---|---|
| RFN SX-E400 | Around 3–6 years | Approximately 90–110cm | Approximately 460mm | Approximately 5mph | Younger beginner or developing rider |
| RFN SX-E500 | Around 4–8 years | Approximately 100–120cm | Approximately 490mm | Approximately 9.5mph | Confident beginner or developing rider |
| RFN SX-E700 | Around 4–8 years | Approximately 100–120cm | Approximately 490mm | Approximately 9.5mph | Confident or experienced young rider |
Age figures are general manufacturer guidance. Rider height, strength, confidence and previous experience may make a different model more appropriate.
Which RFN Warrior Is Best for Each Age?
Our Age-Based Recommendation
Age 3: SX-E400 for a suitably tall and confident rider.
Age 4: usually SX-E400; consider SX-E500 for a taller, confident child.
Age 5: SX-E400 or SX-E500 depending on height and experience.
Age 6: usually SX-E500; SX-E700 only for an experienced rider.
Age 7: SX-E500 or SX-E700, mainly decided by ability.
Age 8: SX-E500 or SX-E700 if the child remains within the physical size guide; taller riders may need a larger youth bike.
Best RFN Warrior for a 3-Year-Old
The RFN Warrior SX-E400 is the only core RFN Warrior model we would normally consider for a three-year-old.
It is the smallest bike in the range and has:
- A rider-height guide of approximately 90–110cm
- A lower 460mm seat height
- Compact 12-inch wheels
- An approximate 18kg bike weight
- A beginner mode of around 5mph
However, the SX-E400 will not suit every three-year-old.
A suitable rider should already balance confidently, be physically large enough to manage the bike and be able to reach and operate the rear brake.
A small or completely inexperienced three-year-old may find a lightweight electric balance bike easier to control.
Best RFN for age 3
Recommended model: SX-E400
Best rider: confident child around 90–100cm tall
Consider something smaller when: the rider cannot support 18kg, reach the brake or balance reliably.
Read our What Age Is the RFN Warrior SX-E400 For? guide.
Best RFN Warrior for a 4-Year-Old
For most four-year-olds, the SX-E400 will remain the most manageable RFN Warrior.
Its lower seat and 5mph beginner mode make it easier to introduce throttle control gradually.
A taller and more confident four-year-old may also be physically ready for the SX-E500.
Consider the SX-E500 when the rider:
- Is close to or above 100cm tall
- Already balances confidently
- Can use separate front and rear brakes
- Can support a 19kg bike
- Is comfortable with a 9.5mph lowest mode
The SX-E700 would not normally be our recommendation for a first-time four-year-old, even if the rider physically fits.
Best RFN for age 4
Default recommendation: SX-E400
Alternative: SX-E500 for a taller and confident rider
Normally avoid: SX-E700 for a complete beginner
Best RFN Warrior for a 5-Year-Old
Age five is the main crossover point between the SX-E400 and SX-E500.
Choose the SX-E400 when the rider:
- Is approximately 90–105cm tall
- Is cautious or relatively inexperienced
- Would benefit from the 5mph beginner mode
- Needs the lower 460mm seat
- Is moving directly from a non-powered balance bike
Choose the SX-E500 when the rider:
- Is approximately 105–120cm tall
- Already balances confidently
- Can use both brakes correctly
- Would look cramped on the SX-E400
- Needs the larger 14-inch chassis
An experienced five-year-old may physically fit the SX-E700, but for most riders the SX-E500 remains the more sensible all-round choice.
Best RFN for age 5
Smaller or cautious rider: SX-E400
Taller or confident rider: SX-E500
Experienced rider only: consider SX-E700 after comparing ability carefully
Read our full RFN Warrior SX-E400 vs SX-E500 comparison.
Best RFN Warrior for a 6-Year-Old
The SX-E500 will usually be the best RFN Warrior for a six-year-old.
Many riders at this age will fit its 100–120cm height guide, 490mm seat and 14-inch wheels.
The SX-E500 offers more space and performance than the SX-E400 while remaining more manageable than the SX-E700.
Choose the SX-E400 for a smaller or particularly cautious six-year-old who still benefits from its lower seat and slower beginner setting.
Consider the SX-E700 when the rider:
- Already has throttle-controlled electric-bike experience
- Uses front and rear brakes correctly
- Accelerates and stops smoothly
- Has progressed beyond the SX-E500 or a similar bike
- Will benefit from the larger battery and hydraulic brakes
Best RFN for age 6
Default recommendation: SX-E500
Smaller or cautious rider: SX-E400
Experienced rider: SX-E700
Best RFN Warrior for a 7-Year-Old
For a seven-year-old, the decision will usually be between the SX-E500 and SX-E700.
Both bikes suit a similar broad rider-height range and use a similar 490mm seat height.
Choose the SX-E500 when the rider:
- Is new to throttle-controlled bikes
- Is still developing confidence
- Needs manageable acceleration
- Would benefit from the strongest all-round RFN option
- Does not yet require hydraulic brakes or the larger battery
Choose the SX-E700 when the rider:
- Already rides an electric bike confidently
- Has good throttle and braking control
- Stops consistently and on command
- Is ready for stronger acceleration
- Will use the additional range and performance
A smaller seven-year-old may still physically fit the SX-E500 better than the SX-E700, while a child above 120cm may need a physically larger youth model.
Best RFN for age 7
Beginner or developing rider: SX-E500
Experienced rider: SX-E700
Taller rider: check whether the core RFN Kids chassis is physically large enough
Read our RFN Warrior SX-E500 vs SX-E700 MX comparison.
Best RFN Warrior for an 8-Year-Old
An eight-year-old may still fit the SX-E500 or SX-E700 when they remain within the approximate 100–120cm rider-height range.
At this age, overall height and physical proportions are likely to be more important than age.
Choose the SX-E500 for a smaller or less experienced eight-year-old who needs manageable performance.
Choose the SX-E700 for a confident rider who already understands throttle control and hydraulic braking.
A taller eight-year-old may look cramped on both models, because moving from the SX-E500 to the SX-E700 increases performance without creating a major increase in physical size.
When the rider is significantly taller than 120cm, consider a larger youth electric bike rather than automatically choosing the SX-E700.
Best RFN for age 8
Smaller or developing rider: SX-E500
Confident rider within the height guide: SX-E700
Above the height guide: consider a physically larger youth model
Best RFN Warrior by Age: Summary Table
| Age | Best Starting Model | Alternative | Main Deciding Factor |
|---|---|---|---|
| 3 years | SX-E400 | Lighter electric balance bike | Physical size and ability to manage 18kg |
| 4 years | SX-E400 | SX-E500 | Height and existing balance confidence |
| 5 years | SX-E400 or SX-E500 | SX-E700 for experienced riders only | Rider height and throttle experience |
| 6 years | SX-E500 | SX-E400 or SX-E700 | Confidence and previous riding experience |
| 7 years | SX-E500 | SX-E700 | Whether the rider is developing or experienced |
| 8 years | SX-E500 or SX-E700 | Larger youth electric bike | Physical height and chassis room |
Why Age Alone Is Not Enough
Two children of the same age may need completely different bikes.
One five-year-old may be 98cm tall and learning to balance, while another may be 115cm tall and already riding an electric bike confidently.
The correct RFN Warrior depends on:
- Overall rider height
- Inside-leg measurement
- Ability to reach the handlebars and brakes
- Strength to support the bike
- Previous bicycle or balance-bike experience
- Previous throttle-controlled riding experience
- Ability to stop safely and follow instructions
Use age to create a shortlist, then use the RFN Warrior size guide to make the final decision.
RFN Warrior by Height
| Rider Height | Likely Model | Key Check |
|---|---|---|
| Below 90cm | Likely below the RFN Warrior range | Consider a lighter electric balance bike |
| 90–100cm | SX-E400 | Can the rider support the bike and reach the brake? |
| 100–110cm | SX-E400 or SX-E500 | Does the rider need the slower beginner mode? |
| 110–120cm | SX-E500 or SX-E700 | Does the rider have enough experience for the SX-E700? |
| Above 120cm | Consider a larger youth bike | Check knee room and standing position |
SX-E400 or SX-E500 by Age?
The SX-E400 and SX-E500 overlap most strongly for riders aged around four to six.
Choose the SX-E400 when the rider:
- Is younger, smaller or cautious
- Needs the lower 460mm seat
- Needs a 5mph beginner mode
- Is learning throttle control
- Is around 90–105cm tall
Choose the SX-E500 when the rider:
- Is taller or physically stronger
- Already balances confidently
- Can use separate front and rear brakes
- Is comfortable beginning around 9.5mph
- Is around 105–120cm tall
SX-E500 or SX-E700 by Age?
The SX-E500 and SX-E700 overlap almost completely by age and physical size.
This means age does not clearly decide between them.
Choose the SX-E500 when the rider:
- Is a beginner or developing rider
- Still needs manageable acceleration
- Is learning front and rear braking
- Has limited throttle-controlled experience
- Wants the best all-round RFN Warrior
Choose the SX-E700 when the rider:
- Already has electric-bike experience
- Accelerates smoothly
- Uses both brakes correctly
- Stops consistently without panic
- Will benefit from the larger battery and hydraulic brakes
The SX-E700 is a performance step rather than a major physical-size step.
Does SX-E700 MX or SM Change the Age Guide?
No. The SX-E700 MX and SX-E700 SM use the same general age and rider-height guidance.
The difference is the tyre setup:
- SX-E700 MX: best for grass, dirt, fields and loose off-road ground
- SX-E700 SM: best for smooth, hard and prepared private surfaces
Choose between MX and SM according to terrain rather than age.
Read our full RFN Warrior SX-E700 MX vs SX-E700 SM comparison.
Should You Buy a Bigger RFN Warrior to Last Longer?
Not automatically.
A larger or more powerful bike may appear to offer better long-term value, but it can reduce confidence when the child cannot manage it comfortably.
The best bike is normally the model the rider can control safely now.
Choose a larger model only when:
- The rider fits the chassis correctly
- They can reach all controls
- They can support the bike’s weight
- The lowest speed mode feels manageable
- Their existing ability supports the additional performance
A child who develops good control on the SX-E400 or SX-E500 will usually progress better than a rider placed on the SX-E700 too early.
My Take as a British Motocross Rider
Age is useful for creating a shortlist, but I would never use it as the final reason for choosing a kids electric bike.
The SX-E400 is clearly the smaller option, so that decision is mainly about physical fit. The SX-E500 and SX-E700 are different because they suit almost the same age and height range.
For those two bikes, the SX-E500 is the right choice while the rider is developing, and the SX-E700 is the right choice once they already have proper throttle and braking control.
Choose the RFN Warrior the child can control confidently today, rather than the highest model their age technically allows.
Best RFN Warrior by Age FAQs
Which RFN Warrior is best for a three-year-old?
The SX-E400 may suit a confident and suitably tall three-year-old. Smaller riders may need a lighter electric balance bike.
Which RFN Warrior is best for a four-year-old?
The SX-E400 will normally be the best choice. A taller and confident four-year-old may compare the SX-E500.
Which RFN Warrior is best for a five-year-old?
Choose the SX-E400 for a smaller or cautious rider and the SX-E500 for a taller or more confident child.
Which RFN Warrior is best for a six-year-old?
The SX-E500 will usually be the best all-round choice. Experienced riders may also consider the SX-E700.
Which RFN Warrior is best for a seven-year-old?
Choose the SX-E500 for a beginner or developing rider and the SX-E700 for a rider with good electric-bike experience.
Which RFN Warrior is best for an eight-year-old?
The SX-E500 or SX-E700 may suit an eight-year-old who remains within the 100–120cm guide. Taller riders may require a larger youth model.
What age is the SX-E400 for?
The SX-E400 is generally recommended for riders around 3–6 years old and approximately 90–110cm tall.
What age is the SX-E500 for?
The SX-E500 is generally recommended for riders around 4–8 years old and approximately 100–120cm tall.
What age is the SX-E700 for?
The SX-E700 is generally recommended for confident riders around 4–8 years old and approximately 100–120cm tall.
Are the SX-E500 and SX-E700 for the same age?
They have a similar broad age and height guide. The SX-E500 suits developing riders, while the SX-E700 suits more experienced riders.
Can I choose an RFN Warrior from age alone?
No. Height, inside leg, arm reach, strength, balance and previous riding experience should all be considered.
Which RFN Warrior is best for beginners?
The SX-E400 is best for smaller beginners. The SX-E500 is usually the strongest all-round option for a taller and confident beginner.
Should I buy the SX-E700 so the child grows into it?
Not unless the rider already has the experience to manage it. The SX-E700 offers more performance but is not significantly larger than the SX-E500.
What is the maximum rider weight?
The core RFN Warrior Kids models generally have a maximum recommended rider weight of approximately 50kg.
Are RFN Warrior bikes road legal?
No. They are designed for private land and suitable riding areas with the landowner’s permission.
Explore the RFN Warrior Range
RFN Warrior SX-E400
Best for younger riders around 3–6 years and approximately 90–110cm tall.
Shop SX-E400RFN Warrior SX-E500
The best all-round option for developing riders around 4–8 years and 100–120cm tall.
Shop SX-E500RFN Warrior SX-E700
The premium model for confident riders around 4–8 years who are ready for stronger performance.
Shop SX-E700Choose the Best RFN Warrior for Your Child’s Age
Choose the SX-E400 for a younger rider who needs the smallest chassis, lowest seat and slowest beginner mode.
Choose the SX-E500 for a growing rider who wants the strongest balance of manageable performance and room to progress.
Choose the SX-E700 for a rider of a similar physical size who already has the experience required for stronger acceleration and hydraulic brakes.
Use age to narrow down the range, then confirm the decision using the rider’s height, physical fit and ability.