How to Buy and Size a Kid’s Bike — Bike Hacks

Cycling is a healthy pastime and one of the best sports activities for your child. It boosts strength and promotes balance and general fitness. But before your child embarks on a journey beyond your lawn, they need a bike suited to their physical strength, size and personal taste. So, in this article, we take a look at how to measure kids bike size and find them their perfect first bike.

How to measure kid’s bike size and what to look for

1. Know what size wheel your child needs

The first step to finding the perfect bike is to measure your child from scratch. Their inseam (crotch to floor) will give you a good indication of their height and bike length. Once you have their inseam measurement, you can use our kids bike sizing chart to find the right wheel size.

In general, if your child is under 10, they will need a bike with 12 or 16 inch wheels. If they’re 10 or older, they’ll need a bike with 20-inch wheels. However, wheel size is only one factor in choosing the right bike for your child. The other key factor is their inseam measurement.

2. Measure their inseam

To accurately measure your child’s inseam, first make sure they are wearing properly fitting shoes. Then, using a tape measure or tape measure, measure from their crotch to the floor.

When you have their inseam measurement, refer to our kids bike sizing chart to find the right size bike.

3. Consider their age, height and weight

In addition to their inseam, you should consider your child’s age, height, and weight when choosing a bike. They may need a bigger bike if they are taller or heavier for their age.

4. Let them test

Once you have a few bikes in mind, let your child test them out to see which one feels best. They should be able to sit in the seat with their feet on the ground and comfortably reach the handlebars. I

5. Get a professional fit

If you’re still not sure which kids bike is right for your child, take it to a local bike shop and have a professional fit it for a bike. They can help you choose the right size and style of bike for your child.

Now that you know how to measure kids’ bike sizes and what to look for, you’re ready to buy the perfect bike for your child. Remember to have them tested first to make sure they are comfortable and confident on two wheels.

Children’s Bike Size Chart

Age child size crotch wheel size type of bike
2–3 years 2’10″–3’4″






balance bikes
3–4 years 3’1″–3’7″






Small Rollers
4–5 years 3’7″–4’0″






Middle rollers
5–8 years 4’0″–4’5″






Road Bikes, Mountain Bikes, Cruisers, BMX Bikes
8–11 years old 4’5″–4’9″






Road Bikes, Mountain Bikes, Cruisers, BMX Bikes
11 years and over 4’9″+






Road Bikes, Mountain Bikes, Cruisers, BMX Bikes




A balance bike is a perfect bike for a 3 year old. They are ideal first bikes for toddlers and preschoolers (2-4 years old). They help riders develop a sense of balance and learn to steer before they start pedaling. Most importantly, balance bikes let kids have fun while learning to ride.

These children’s bikes are usually equipped with 12-inch wheels. They are pedalless and may or may not include a brake. Usually children have to focus on using their feet and legs to move forward and to stop. So if you don’t want give your child a toddler cargive them a balance bike instead.


Small wheels are a great option for kids who are too big for their balance bike or their first pedal bike. These are the first basic pedal bikes, which means they have all the features of larger bikes, like freewheel hubs and hand brakes. Although they are bigger than balance bikes, you can still take a small wheel on a family road trip.

These bikes typically have 14-inch wheels and taller seat heights, making them more suitable for longer rides. Small wheels usually have coaster brakes, but some models have hand brakes. If possible, opt for coaster brakes. These brakes require less manual dexterity and hand-eye coordination.


These bikes are designed for children aged 4 to 6 or those between 110 and 120 cm tall. Like 12-inch and 14-inch bikes, 16-inch bikes usually have coaster brakes. However, some models are equipped with hand brakes.

Intermediate wheels are a great option for kids who have outgrown their small wheel bike or are ready for their first “big kid” bike. These bikes typically have 20-inch wheels and taller seat heights, making them more suitable for longer rides. The mid wheels also have a set of gears, freewheel hub and steel/aluminum frames. Some scooters for children also fall into this category.

These bikes allow your child to pick up real speed. Therefore, your child should have the hand-eye coordination skills and dexterity necessary for balance.

Note: If you want to know the perfect size bike for a 7 year old, consider the following bikes.


These bikes are designed for children aged 5 to 9 or those between 120 and 135 cm tall. These bikes will have gear sets, hand brakes, suspension systems, etc. Bike manufacturers in this category often use terms such as “road bike”, “mountain bike” or “cruiser” to attract customers. This means that this is the level where specialization begins. So expect a variety of styles and features.

Therefore, consider the type of riding your child will undertake: off-road, racing, on-road, jumping, etc. Remember that a good bike is not cheap. If you are not careful with your choice, you may end up with a model that may not suit their needs.


BMX is the best kids bikes. They are perfect for kids who like to ride hard and fast. They are built to handle all the bumps and jumps of BMX riding. Initially, they were designed for dirt racing on nervous tracks. However, they have much wider appeal today.

Most BMX bikes have 20 inch wheels, but some models have 24 or 26 inch wheels. They are built to be tough and for tough rides. Additionally, these bikes are usually single-geared and feature a lightweight frame and knobby tires.

BMX bikes include Cantilever, VB-rakes, U-Brakes, Gyro, Coaster, Caliper or Mechanical Disc Brakes.


Think of these bikes as more of a transition bike to adult bikes. Indeed, they are equipped with adult bike features such as front suspensions, up to 36 speeds, etc. Some of them even come with advanced features like hub brakes. However, these extra features mean higher prices and more chances of getting it wrong.

BMX bikes, cruiser bikes, mountain bikes, and road bikes are all available in the 24-inch wheel category. Usually our advice for choosing a bike in the category is to go for simple options.

What to do when your child is between sizes or too big for their bike

train on a bike

If your child is between sizes or too big for their bike, don’t worry! Here are some actions you can take:

– Look for a bike with a height-adjustable saddle and handlebars. This will give your child extra space to grow.

– Get a bike with bigger wheels. For example, if your child is between the sizes of a 16-inch bike and an 18-inch bike, get the 18-inch bike. The larger wheels will make it easier for your child to ride.

– Get a bike with coaster brakes. Coaster brakes are easier to use than hand brakes, so they’re a great option for kids who are still learning to ride.

With a little research, you can find the perfect bike for your child.

Where to buy children’s bikes?

bicycle shop

Here are some places where you can buy children’s bikes:

Local bike shops

Bike shops usually have a good selection of children’s bikes. They can also help you find the right size and make sure the bike is properly adjusted.

Online retailers

There are many online retailers that sell children’s bikes. You can often find great deals on bikes at online retailers. Just be sure to complete your research before buying to ensure you get a quality bike.

Department stores

You can sometimes find children’s bikes in department stores. However, it is important to note that not all major stores carry quality bikes. We suggest sticking with reputable brands that you know and trust.

No matter where you buy your child’s bike, make sure you get the right size, well-tuned bike. With a little attention, your child will be riding on two wheels in no time!

Key points to remember

So hopefully now you know how to determine the size of a child’s bike. Here are three things to remember:

1 – Use your child’s height and inseam to find the right size bike.

2 – If your child is between two sizes, opt for a bike with larger wheels or an adjustable saddle and handlebar height.

3 – When in doubt, always err on the side of caution and buy a bigger bike. Your child can still grow on it, but they can’t ride a bike that’s too small.

Good luck!

Back To Top