Kids Bike Sizes Guide

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Last Updated on February 8, 2022

"Daddy, this seat hurts; Mommy, this bike's too heavy!" As a parent, these are the last words you want to hear from your kids when it's barely a month after you've bought them that brand new bike.

As it is, finding the right kids' bike size requires more of a technical approach than a random guess. It's no secret that your kids grow faster than you'd expect. However, you still want them as much fun as possible growing up. 

Bike riding is still one of the best ways to make sure they get out and make sweet childhood memories. Remember your first time riding a bike? The good old times.

So how do you pick out a bike that your child can enjoy for years to come?

It's simple, really, but it requires you to have an eye for detail. So if it's your first time looking for a good match for your child or you've made a few mistakes along the way. Here’s a complete guide to help you maneuver the process. 

In the end, it'll save you the time and effort that you put in finding the perfect match for your child, not to mention the stress that ensues.

But first, here are a couple of things you must know before diving into the deep end.


What to Consider before Buying your Kid a Bike

Age & Height

Ideally, the best place to start when determining your kid's bike size is age and height. Rightly so, because you're less likely to make an error in judgment when you've got the numbers right, but that's not always the case.

At times there are other important factors come to play. Like;

Ability & Confidence

While your kid's age and height are clear signs that the bike is a perfect match, you should also consider their ability to handle such a machine. You see, not all kids are the same, and even at the same age, they show different potential.

For example, you may find that your eight-year-old child isn't confident enough to handle a bike that suits their age, while to others, it's relatively easy. 

Well, it is perfectly normal, as a parent you just have to weigh the confidence they show in different stages of life. As such you'll be able to determine if they require things like;

  • Training wheels
  • A bike Stand
  • Tighter brakes

Knowing your child's strengths and weaknesses gives you an edge in the market.


Your child's outlook determines the type of bike you should go for; In any case, they should be able to:

  • Comfortably sit on the saddle with the balls their feet on the ground
  • Reach the outward handlebars while their arms slightly bend and have a grip on the brakes. They should be able to do this when they sit on the saddle.
  • Shift the top bar with ease when both feet are on the ground

Bike Weight

Can you imagine your child struggling to ride a bike that's more than half their weight? It's a disaster, to say the least; they'll have a hard time moving around, let alone bending a corner.

To prevent that from happening, make sure your kid's weight is slightly more than that of the bike. It'll help them to steer and balance better.

A Boys' vs. Girls Design

Is there a specific design for any gender? Well, it doesn't matter, especially if you are dealing with toddlers. At such a point, all that matters is the child's safety.

In fact, as a parent, you'll find that the bike design for girls is more comfortable and safer to use. Most have a smaller step through making it easier to get on and off. In terms of strength, their difference is negligible.

The only detail you should consider is the color. In most cases, a girl's bike has bright colors that might not appeal to boys. So in essence, it has more to do with a social view than anything else.

Remember, if you're dealing with young teens, the design is everything. Don't go choosing a girls' bike design for your ten-year-old son. They'll probably hate you for it.

However, the search doesn't end there. That's just a tip of the ice when looking for the perfect kids' bike sizes. For a better result, your approach should be more practical. Once you're sure that everything checks out, you can proceed.

How to find a Bike that's perfect for your Kid

Measure your child's inseam

If you've never heard of the word inseam before, it's typically referring to the space between your legs.

How does it help you to determine your kid's bike size?

The length of the inseam acts as a representation of the distance between the seat of the bike and the foot pedal. So to get a good idea of the range, you should measure inseam using the following steps.

How to measure your kid's inseam

  • Let your child stand upright with their back against a wall.
  • Spread their feet 3-4 inches apart
  • Take a book and place it between the legs
  • Raise the spine of the book until it hits the crotch
  • Make sure the book is level with the ground and measure the distance from the ground up to where the spine comes into contact with the crotch area.

Why is it important to measure your child's inseam?

The figure you derive will influence:

  • The Wheel size
  • Your child's ability to ride
  • Your decision on the best bike for the present and future 

How inseam helps you determine the Right Wheel Size

In essence, the size of a bikes tire and frame determine the seat height. Therefore, you can quickly identify the right wheel size for your child.

To help you get a better idea of how to match inseam to wheel size, we've come up with the table below as a guide.                                                                    

Wheel Size


Inseam (inches)

Inseam (cm)




30-35 cm




35-42 cm




40-50 cm




45-55 cm




50-60 cm




55-62 cm




60-72 cm




72+ cm

How inseam influences your child's Ability to Ride

Let’s take a look at two possible scenarios:

A Balance Bike

If you prefer your child to have a balance bike, then you should go for a bike seat that is 1-1.5 inches lesser than your child's inseam height. It allows the feet to have a slight bend when they sit on the saddle. That way, the bike runs smoothly.

A Bike with Training Wheels

If you’ve ever seen toddler ride a bike before, you’ll notice find that they mostly use their feet as a way to stop the bike in motion.

Any bike that has support wheels should be 0-3 inches more than your kid's inseam height. As such the tip of the toes should touch the ground while they are seated. It helps them to stop the bike with their feet.

How Inseam Influences your Present and Future

You should always go for a bike that fits your child at the current stage. Any alteration to the size, say a larger size will cause trouble when they are riding.

So what if you want the perfect size that has room for growth? After all, you want them to enjoy the bike years ahead. 

If that's the case, then your kid's seat height should be somewhere near the bike's lowest seat height. It’ll leave enough room for when your kid gets older.

Now that you have the basics for your kids' bike size, the only thing left is to hit the store and purchase one, right? Well, not entirely, here are some things you should look at as a safety measure.

How to Ensure the Safety of your Child when Riding a Bike

Check the Brakes

As much fun as riding a bike can be, it is also dangerous. So one way to make sure your child is safe, whether they are on the road or around your house, is by making sure the brakes work.

That is not all; you should also make sure your child can easily pull the brake. Remember, children have inferior hands, and if the lever is too tight, they won't be able to pull.

So how do you know if the break is suitable for your child?

You can conduct a test to see if the brakes work by using your pinky finger to try and pull the brake. If it's pulls with ease, then that's a good sign. If not, look for better options.

Insist on a Good Helmet

As a rule, every bike should come with a helmet and not just any type of helmet. The kind of helmet we're talking about is the one which even if your child happens to fall and hit head first, there's little to no trauma.

Accidents happen all the time when riding a bike, so you should always make sure your child has a helmet each time they are riding a bike.


Riding a bike is one of the most beautiful experiences that a child has. However, with the wrong bike size, your child may end up hating riding all the same.

So before you surprise your kid with a bicycle that they always dream of make sure you have the basics right.

Harold Whitford

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About the Author

My name is Harold Whitford, a husband, father, and avid cyclist with a Bachelor’s degree in Sports Management from the University of Delaware. Having been in the industry for more than 15 years, I have a number of the road race and national time trial championships in my bag.

  • What’s the right bike size to get a tall kid? My son is 7, 130 cm tall with an inseam of 60 cm. Been thinking of getting him a bike between 20 and 24 inches, but I’m not sure which option is ideal

  • My ten-year-old son, who is on the shorter side, is 4 feet and 4 inches with an inseam of 23.5. Would a 20 inch bike be a good fit?

  • What’s the right way to get the inseam of my child? Should they be wearing shoes or should they be barefoot?

  • I’m looking for a good bike for my son. He just turned 10. He is 4 feet 4 inches tall with an inseam between 23 and 23.5. What’s the right frame size for him?

  • My daughter is growing fast. Her current height is 3 feet and 9 inches. And her inseam is 16 centimeters. What is the right bike size for her?

  • I’m thinking of getting a small mountain bike frame with 27.5 or 26 inches wheels. Will it be okay for my daughter or should I go for a smaller frame instead?

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