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Understanding Kids Bike Sizes and How to Choose The Perfect Size

Kids Bike Size

One of the most confusing things for any parent is getting the right size bike for their kids. Why? Simply because kids are growing up every day and a perfect-sized bike today will be a less-than-ideal-sized bike in three months.
Furthermore, there are many questions and variables to consider when buying kids’ bikes. What is the right wheelbase? What’s the right height? What is the right distance between the handle and the seat? What is the best wheel size? And so many more.
If you are a parent looking to buy a bike for your kid, the first step is to find the best and most comprehensive information. Luckily, you’ve come to the right place. This blog post explains everything you need to know about choosing the right size of bike for your kid.
Let’s discover more!

The Size Chart

Infographic provided by Two Wheeling Tots

Most kids’ bike retailers will offer a size chart based on the height and age of your kid. The first thing you need to do as a parent is to read through the chart and choose bike models that are in the category of your kid’s age and height.
Moreover, it is always a good idea to take your kid with you when shopping for a bike. This allows them to test ride the bike and give you feedback on how the bike feels. Most importantly, the bike should feel comfortable to ride for your child.

The Inseam

An even more accurate way of selecting the right size of bike for your kid is via the inseam. This is the distance between the floor and your kid’s crotch.
To measure the inseam, get your child to stand with their back against the wall. Then ask them to spread their legs 3 to 4 inches apart. Subsequently, place a book with the spine up between the kid’s legs and hold it. Lastly, measure the distance from the spine of the book to the floor. This is your kid’s inseam.
When buying a bike, the book mimics the position of the seat.

How to Use the Size Chart

Note that there are slight variations in the size charts between different sellers. But these are usually minimal. The size chart will normally contain 4 main categories. These include the following:

  • The Kid’s Age

Kids’ bike size chart will begin at 2 to 4 years. At this point, the child has not yet developed good hand-eye coordination skills. Consequently, the chart recommends a toddler bike or balance bike. These provide balance and allow the kids to practice using pedals.
That said, you might decide that 2 to 4 years is too young to start riding. This is okay and most kids will begin riding bikes at 4 to 6 years. The kids’ bikes recommended for this age group will have pedals. It is a good idea to pick one with training wheels or stabilizers before the kid develops balance. However, it is also perfectly okay to get a bike without training wheels as these can be bought independently and fixed on the bike.

  • The Kid’s Height

The height is a crucial component in picking the right size of bike for your kids. For instance, not all kids at 3 to 4 years will be 90 cm to 100 cm tall. Some will be taller than this while others may be shorter than this. Therefore, the best way to choose the right bike size for your kid is by considering their individual height.

  • The Kid’s Inseam

Similar to height, you should consider the inseam independently. Not all kids between 3 and 4 years will have an inseam of between 35 cm and 42 cm. Take your kid’s individual measurements and use these to pick the right bike size for them.

  • The Wheel Size

The diameter of the wheel influences all the other major factors on the bike. Kids’ bikes come with 12”, 14”, 16”, 20” or 24” wheel sizes. Generally speaking, kids who are only just beginning to ride a bike should get a 10” or 12” bike. These kids are usually between 3 and 5 years old. On the other hand, older kids of around 14 years can ride a size 24 bike.
How to Choose a Kid’s Bike Using Their Age

  • 2-4-year-olds

Kids in this age bracket are only just starting out to ride a bike. Therefore, it’s important that the bike has a simple design with no whistles, bells, gears, or handbrakes. These will confuse the child and make the learning process that much more difficult.
The best bike for kids at this age is a toddler bike or balance bike with a 10” to 12” wheel diameter. Since the kid still hasn’t developed good coordination skills, they’d find it hard to balance themselves.
Balance bikes are a great way to help your child develop a sense of inertia, as well as knowing how to steer the bike. Granted, they lack pedals and the only way a kid can propel forward is by using their feet and legs. However, they are designed for safety and are a great way to build confidence.

  • 5-8 years old

As kids grow, they develop better coordination skills and become more confident. At 5 to 8 years, they are ready to graduate to a bike with 14” to 18” wheels. The kids’ bikes in this category have a similar design to adult bikes. Check out the best bikes for kids and adults. Consequently, there are many different designs from different manufacturers available in the market. This can be quite overwhelming when trying to choose the best model for your kid.
As we noted above, the main factor to consider when choosing the right kid’s bike size is how comfortable it is to ride. Furthermore, unlike the toddler bikes, these bikes have pedals. Ultimately, this means the kids are now more prone to accidents.
A bike that is too large or too small for your kid will increase the rate of crashes and falling. Therefore, it is important to choose the right bike size. Your kid’s feet should reach the ground for support and the hands should comfortably reach the handles.

  • 9-15 years old

Naturally, the more your kid grows, the larger the bike they can ride. Keep in mind that kids’ bikes only get to 24 inches. However, some kids will grow taller than other kids will. As kids get into their upper teenage years, the really tall ones can begin using adult bikes.
Take care not to buy an adult bike before a kid is ready. To ensure that you pick the right size bike, observe all the other factors mentioned above. Regardless of age, the bike should always fit your kid and not the other way around.
Furthermore, at this age, kids can also handle bikes that have gears. Such bikes, however, require more maintenance and it is more likely for something to go wrong due to the higher number of moving parts.

Height is Not Everything

Height is undoubtedly a very crucial factor when picking kids’ bike sizes. However, it is not THE most important factor. While it is a great starting point to guide you in selecting the best size bike for your kid, at the end of the day, the bike needs to be comfortable for your kid to ride.
This means that the sitting position, arm position, and leg movement should all be just right. On the other hand, given that there are no numbers to work with, the best thing is to have a test ride. Ask your kid to ride the bike, and observe their body position and leg movement. Then see if it is the right bike for them or if you need to pick a new one.

Let Your Kid Decide

Many parents often make the mistake of buying their kids something they do not want. Parents hope that, over time, the kids will appreciate the item. While kids may change their minds, other times they may not. Moreover, the last thing you want is for your kids to develop a negative attitude towards riding a bike.
Once you have chosen the right size bike, let them make the final choice and pick the bike they really want. Otherwise, you run the risk of the bike ending up in the garage collecting dust. All the while, your kid is growing and demanding a new bike.
Choosing the right kids' bike sizes is never easy. However, with the right information, you can handle it like a pro.

Picking a Bike That Fits Your Kid

Before teaching your kid how to ride a bike, it is paramount that the bike fits the child and never the other way around. This will help to keep them safe.

Sitting Position and Balance

A bike that is too small creates an uncomfortable sitting position and your kid will not enjoy the riding experience. On the other hand, it will be much harder to control and maintain balance on a bike that is too large.
The most comfortable sitting position should be upright. The handle should also be the right distance from the seat. If it is too close, the knees will hit the handlebar when changing direction. If the handle is too far, your kid will lean forward aggressively, resulting in an uncomfortable seating position.
The ideal position for the handlebars is where the arms are stretched out with only a slight bend at the elbows. This provides enough clearance for turning the handlebars without hitting the knees.
An effective way of choosing the right bike size is to measure the wheelbase. This is the distance between the front and back wheels. The wheelbase should have an optimum length and should be neither too large nor too small.

The Center Tube

Your kid should always be able to reach the ground with both feet when standing on top of the center tube. Moreover, there should be a one or two-inch clearance between the center tube and your kid’s crotch. A bike with a center tube that doesn’t allow both feet to touch the ground is very likely the wrong size for your kid.
The importance of checking the height of the center tube becomes apparent when your kid is forced to quickly get off their seat. A high center tube will result in injury.

The Gears

Most kids’ bikes are single-gear models. That said, it is important to check the size of the cogs. Larger cogs result in a bike that is harder to get moving but covers more ground with each pedal. On the other hand, a small gear creates a bike that is simple to get moving but requires more effort when the kid needs more speed.
You can choose the right gear for your kid by asking them to take a test ride. If you notice that your kid is struggling to get the bike moving, then simply go lower on the size of the gear.


Durability is important when choosing a bike. Small kids are likely to fall or drop the bike frequently. Therefore, the kid’s bike needs to be able to take the constant beating. Bikes that have gears are more likely to break down, so keep this in mind when choosing a bike for your kid.
While older kids can get a bike with gears, younger kids may only end up damaging the gears due to the regular dropping.

The Weight

Check the overall weight of the kid’s bike. Generally, the size of the bike is directly proportional to its weight. Ideally, the weight of the bike should be 40% or less than the weight of your child.
Small kids will not be comfortable riding a heavy bike even if the bike is the right size for them. A light yet durable bike is much more comfortable.
Lastly, always talk to a bike expert before making the final decision. They can save you a lot of time searching the internet for the right information. Remember, an expert has plenty of experience with different manufacturers and models. Therefore, they can point out which model is more durable and what issues to expect with other models.


The simplest way to pick the right bike size for your kid is to begin by reading the size chart. The information contained on the chart is based on dimensions as per the kids age. That said, the most accurate way to choose the perfect bike size is to bring your kid along and ask them to do a test ride.