What Size Bike for Kids: A Complete Guide

 

Why Bike Size Matters

Choosing the right bike size for your child is crucial for their comfort, confidence, and safety while riding. It’s tempting to buy a bike your child can “grow into,” but oversized bikes often feel uncomfortable and difficult to control and can be unsafe. Instead, focus on finding the right size for your child’s current height and skills. A well-fitted bike ensures that your child enjoys their cycling adventures and develops their skills quickly.

Whether you’re looking for a balance bike for a toddler or a 20 inch bike for an older child, this guide will help you determine the best kids' bike size for every stage of growth. 

How to Determine the Right Size Bike

Kids' bikes are classified by wheel size, which serves as a general guide for selecting the right fit. However, bikes with the same wheel size can vary in frame geometry, seat height, and overall fit.

To ensure the best size for your child, it's important to consider their height or inseam (the measurement from the ground to their crotch) and refer to the manufacturers size guide. To determine the correct size:

1. Measure Your Child’s Height: Use a tape measure to get their current height.

2. Measure Their Inseam: Have your child stand against a wall and measure from the floor to their crotch. The base bikes sizing page has a video to walk you through this.

3. Match Measurements to Wheel Size: Most kids' bikes manufacturers include a size chart to help you match the appropriate wheel size to your child’s height and/or inseam, with inseam being the more accurate measurement for determining the best fit. Click here for the base bikes size chart.

Although the above guidelines will work well for most kids, there are other things to consider when determining the right size bike, especially if your child is at the high or low end of the size range for a bike.

• Seat height: Two bikes with the same wheel size can still fit differently due to variations in frame design and seat height. It’s crucial to check that your child’s inseam allows them to comfortably touch the ground when seated. For timid or beginner riders, ensure their feet can sit flat on the ground while seated. To achieve this, their inseam (with shoes on) should exceed the seat height. This provides a sense of security and boosts their confidence as they learn to ride.
• Top tube clearance: Ensure there is at least a 2-3 cm gap between your child’s crotch and the top tube when they are straddling the bike. This clearance is important for comfort and safety, especially during sudden stops or dismounts.
• Skill level: It is also important to consider a child’s skill level. Beginner riders are still developing their balance and coordination, so a properly sized bike—where they can easily touch the ground and feel in control—is essential for building confidence. On the other hand, more experienced or skilful riders often have better balance, strength, and confidence. They can adapt to a larger bike more easily, even if it’s slightly above their current size. This is because they’re less reliant on placing their feet on the ground quickly and can manage the weight and geometry of a bigger bike. In practical terms, a beginner might stay with a smaller bike to focus on control, while a more skilful rider may "size up" sooner, especially if tackling varied terrains or looking for a bike that will last them longer.

Bike Sizes  

Balance Bikes (Typically ages 2 to 4)

• Wheel Size: 10-12 inches

• Who It’s For: Perfect for toddlers learning to balance and steer. Balance bikes have no pedals, allowing kids to push with their feet and focus on coordination and balance.

• Best Fit: The seat should be low enough for your child to place both feet flat on the ground. They should be able to comfortably grip the handlebars.

14-Inch Bikes (Typically ages 3 to 5)

• Wheel Size: 14 inches

• Who It’s For: Ideal for kids who are transitioning from a balance bike but still need stability and confidence.

• Best Fit: Ensure your child’s knees have a slight bend when seated and their feet are at the lowest point of the pedal motion. Your child’s feet should comfortably reach the ground when seated. For beginner or timid riders, the seat should be low enough for your child to place both feet flat on the ground. Ensure they can comfortably grip the handlebars and apply the brakes.

16-Inch Bikes (Typically ages 4 to 6)

• Wheel Size: 16 inches

• Who It’s For: A great option for kids who are transitioning from a balance bike or for young riders who are already pedalling independently. 

• Best Fit: Ensure your child’s knees have a slight bend when seated and their feet are at the lowest point of the pedal motion. Your child’s feet should comfortably reach the ground when seated. For beginner or timid riders, the seat should be low enough for your child to place both feet flat on the ground. Ensure they can comfortably grip the handlebars and apply the brakes.

20-Inch Bikes (Typically ages 5 or 6 to 9)

• Wheel Size: 20 inches

• Who It’s For: Perfect for kids with more confidence and strength, ready for longer rides and rougher terrain. Some 20-inch bikes include gears so they can manage better on hills and to be able to go faster.

• Best Fit: Ensure your child’s knees have a slight bend when seated and their feet are at the lowest point of the pedal motion. There should be at least 2-3 cm of clearance between the top bar and your child’s inseam when standing. Ensure they can comfortably grip the handlebars and apply the brakes and place their feet on the ground when stopping.

24-Inch Bikes (Typically ages 9 to 12 years)

• Wheel Size: 24 inches

• Who It’s For: Best for older kids who are nearly ready for adult bikes. These bikes often come with multiple gears and larger frames. Many will have suspension options too.

• Best Fit: Ensure your child’s knees have a slight bend when seated and their feet are at the lowest point of the pedal motion. Ensure your child can comfortably grip the handlebars, apply brakes and change gears, and place their feet on the ground when stopping.

Tips for Finding the Best Kids Bikes

• Prioritise comfort and safety: Check that the bike’s brakes, handlebars, and saddle are easy for your child to use. 

• Look for a lightweight bike: This makes it easier for kids to start, stop and control, boosting their confidence and reducing fatigue. For four or five year olds, even a small difference in weight can significantly impact their confidence and enjoyment. Plus, it’s lighter for parents to carry!

• Consider their ability: If your child is a beginner or a more timid rider, ensure they can easily place their feet on the ground. This will help them feel secure. Also consider a bike with a more upright riding position as this will feel less intimating to them.

• Consider the ease of riding: For example, look for a bike with a low geometry. This is more stable and easier to balance, but also reduces the distance their feet need to move to go from the pedal to the ground when they want to stop, helping them feel secure. Look for other features that make the bike easy to ride, such as a low q-factor (distance between pedals) to ensure they do not 'splay' their legs when riding, and appropriately sized cranks for their size. Many bike brands miss these important features for kids.

• Don’t Skip Adjustments: Ensure the bike is fully adjustable. For example, many kids bike seats cannot be adjusted forward or backwards, this limits adjustability. As kids grow, adjust the saddle and handlebars to maintain the best fit.

FAQs: What Size Bike for Kids?

1. How do I know if the bike fits my child?

   • Ensure your child’s knees have a slight bend when seated and their feet are at the lowest point of the pedal motion. Ensure they can comfortably reach the handlebars and apply the brakes.

2. Should I buy a bike they can grow into?

   • It’s better to buy a bike that fits now and adjust as they grow. Oversized bikes can be unsafe. However, you may find that a larger bike can be 'dialled down' to ensure a proper fit and will provide more years of use (for example, by rotating the handlebars toward the child and moving the seat forward - always follow Manufacturer's instructions).

3. What’s the best kids bike for beginners?

   • Balance bikes are ideal for toddlers, while a 16-inch bike works well for slightly older beginners. Consider the balance bike method for learning to ride a pedal bike.

Choosing the right size bike sets your child up for a fun and safe cycling experience. With the tips above, you’ll be able to confidently select the perfect kids' bike size, whether it’s a balance bike for your toddler or a 20 inch bike for your growing adventurer.

At base bikes, we believe we’ve created the best kids bikes - but we’ll let you decide!