How to Size Kids Bike

Nobody needs to tell you that kids grow fast! Whether your child is just beginning new adventures, or they’ve outgrown everything, the day will roll around when you need to buy a new bike and you need to buy the perfect best which will bring you to: how to measure kids bike size.

You’ll do all your research and find the perfect bike! But what size bike do kids need? What about knowing how to size kids bike? And how quickly will they grow out of it?

Biking sizing is confusing, and on ever-growing children it can pose an even bigger challenge. This article will help you have, not only the perfect bike, but also the perfect fit! And a good fitting bike is your child’s key to many years of fun, safe, and successful riding. Let’s dive in to learn about what size bike for kids is best!  

Why is kids bike size important?

You might be wondering whether the size of your child’s bike will make a difference? It does! The reason why is that at different ages, stages, and riding abilities, kids need to be able to get into certain positions for their own safety and success. There’s a lot of factors to consider when determining what size bike for kids is most ideal.

For example, a young child that’s just starting to learn how to ride their pedal bike might not be confident enough, or stable enough, to balance on their tiptoes. They will need their bike to be low enough to allow them to rest their foot flat on the ground when they’re taking a break.

On the other hand, if an older child is stable and confident on their pedal bike, they might not need their foot flat on the ground. This is more ideal because these more confident riders will be able to properly extend their legs and balance while pedaling on the bike. Otherwise, if they were too low to the ground, they wouldn’t be maximizing their leg stroke and, as a result, wasting a lot of energy 

What sizes do kids bikes come in?

Knowing how to measure kids bike size will help you get that perfect fit and ensure enjoyable rides for many seasons to come! You can use this information, alongside a kid’s bike size chart, to find a professional fit for your child.

Are you asking yourself, what size bike do kids need anyways? Companies use several standard ways to measure and compare bike sizes. The most common measurements that you will use are the wheel size, the frame size, and the seat height (which is usually adjustable). 

Wheel Size

The wheel sizes available by most companies are typically 12, 14, 16, 20, 24, and 26 inches. Companies will often pair a wheel size with a child’s age. So, for example, a 16” wheel bike is suited to children 4 – 6 years old. This isn’t a foolproof approaching to sizing kids’ bikes, though.

It’s no surprise that children grow at their own paces and come in all shapes and sizes! That means that relying on age to size a bike won’t ensure a proper fit. You might be able to narrow down your options using your child’s age, but then you’ll need to incorporate other measurements to get to the precise fit you’re looking for.

Frame Size

The frame size can vary more than wheels. Most standard bike companies will provide a bike frame chart with a number of useful measurements. When you’re looking at a particular bike, you can pay attention the frame height, the length of the bike frame, and the handlebar height. A taller child will benefit from a bigger bike frame. And if that child is also a confident rider, they can manage being on a bike that puts them in a proper riding position — which would be too stretched out for children who are just learning to ride. This is how you measure kids bike size by height.

Seat Height

Seat heights are typically adjustable and will range between a few inches. Adjusting the seat height will help you create the perfect custom fit to your child, and to raise the height as they grow. Depending on the type of bike you’re looking at, you will want to pay closer attention to the minimum seat height. 

For example, if you’re looking at a bike height chart for a balance bike, your child’s inseam measurement (we will cover this below) must be at least as tall as the minimum seat height. That’s because, at a minimum, you want the child’s feet to be flat on the ground when the seat is at its lowest.

Balance vs Pedal Bike

Whether you’re looking for boys’ bike sizes or girls bike sizes, the type of bike you’re looking to buy will also determine the sizing and fit. In general, balance bikes need to be a smaller fit compared to pedal bikes. That’s because kids on a balance bike must be able to easily stand and push off the ground with flat feet. While they’re learning, using their feet on the ground is the only way to stop, balance, and move forward! So, a properly fitted balance bike that allows them to do that is key!

On the other hand, children won’t need to rely on their feet touching the ground when riding a pedal bike. In fact, if they’re too low to the ground, it could make pedaling more difficult. Generally, when a child first transitions to a pedal bike it should be small enough so that their feet can comfortably rest on the ground when they’re sitting on the seat. 

The bike should have plenty of room to grow though! As riding abilities improve, you can raise the seat height to allow kids to use a full range of motion with their legs. At the same time, kids should still be able to stand over the top tube with flat feet and rest their toes on the ground when in the seat.

How does riding ability influence kids bike size?

Balance Bike Rider

Riding ability will help you decided how to measure a bike size for kids. For kids just starting out on balance bikes, the seat height will need to be about 1” – 2” shorter than their inseam height. The reason for this is to allow them to rest their feet flat very easily on the ground to stop, balance, and push forward.

Beginner Pedal Bike Rider

Once kids graduate to a pedal bike, the seat should still remain fairly low. Learning to transition from a balance bike to a pedal bike will still require some practice — and more tumbles. To help kids gain confidence and skill pedaling, make sure their feet can rest flat on the ground while sitting on the seat. 

Experienced Pedal Bike Rider

As kids get better with their pedaling and steering, the seat can be raised to allow them to use the full range of motion in their legs. Children should always be able to stand comfortably over the top tube of the bike, though. You can check a company’s bike frame chart to find the height of the top tube and measure that against your child’s bike inseam.

Read more on balance bike HERE.

How do you measure the right size bike for your child?

There are three main factors to consider when selecting a kid’s bike size, as we talked about in the sections above. Each method can be used on its own, but it’s best to consider all three together when sizing kid’s bikes. Let’s take a closer look at how to measure kids bike size!

So, what size bike do kids need? There are two main approaches that exist for kid’s bike sizing: there’s “the old way,” which was to use a child’s age to find the best wheel size, and “the new way,” which is to use a kid’s bike inseam to find the right bike size. 

Two Ways to find your kids bike Size:

The Old Kids Bike Size Guide

The old way of choosing kids bike sizes is based on a child’s age and matching that with appropriate wheel size. As we talk about above, though, this isn’t always the best way to find the right bike size. Children of the same age can be different heights, so that a 14” wheel could be much too big for one child, yet far too small for another! 

Not only that, but kids riding abilities will also naturally vary. Some kids are ready to take off on their toes, meanwhile others need some more stable footing for a little while longer. 

The New Kids Bike Size Guide

The new way of choosing a bike size is based on a kid’s bike inseam. This is essentially selecting a bike size by height.

A bike inseam is measured with the child wearing shoes, and spans from a child’s seat bones straight to the floor. This number will determine the minimum seat height you need to get them rolling. 

For example, if a child’s bike inseam is 16” that means that the minimum seat height on a bike height chart has to be 16” to allow them to stand with both feet flat on the ground.

This method for bike sizing is ideal because it ensure that the bike’s height and functions are all accessible to your child’s actual size, not merely the average size of other children their age. 

Of course, when you’re shopping for a new kid’s bike, each company will offer a range of specs on their kid’s bike size chart that you can use when finding the right size. And many kid’s bikes are quite customizable and adjustable to fit your needs. So, when you’re looking for the right bike size take into account the various measurements you have available. This method for finding kids bicycle sizes will work whether you’re looking for girls’ bike sizes or boys bike sizes.

How do your account for growing children?

On paper, this all sounds fine and dandy, but in real life sizing kids’ bikes won’t always align perfectly with the bike sizes available. Sometimes, kids will fall right on the border of a kid’s bike size chart, just an inch or two away from the size up. You don’t want to invest in a new bike only for it to be outgrown in a season. How to measure a bike size for kids in these borderline cases?

In these cases, it’s generally a good idea to size up. This might depend on a few factors and may not be a good idea in all cases. To help you decide on bike sizes for kids, think about how confident your child is with a pedal bike, consider their general size, strength, and athletic ability, and consider whether they could manage taking on a bit of a challenge with a slightly bigger bike. If you think your child can manage with all of this, then sizing up will ensure you get many seasons out of the new bike. 

If this isn’t a good option for your child, stick with the sizing that will work best for them and look into buying or borrowing a secondhand bike. You may need to replace the bike the next season, but your child will develop much better skills riding a bike they feel safe on. 

Once you’ve determined your bike sizes for kids, you can look into different types. There are even different types of balance and pedal bikes. You can figure out the type of biking you’ll mostly be doing and then get the right gear to match!

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What ways do you measure kids bike size or do you just buy the cutest bike? let me know in the comment section.