Guide to kids' bike wheel sizes

Choose the right sized wheels for your child

Children grow up fast, but luckily there's always a bike for them, no matter how old or how tall they are. Both the frames and the wheels of the bike vary in size, and the wheel size is a key factor in determining what bike is right for your child.

Here’s a quick guide to the main wheel size options and what to look for. In every size, you should make sure you child can comfortably reach the handlebars, can stand astride the frame without contacting the top tube, and can safely operate the brake levers.

The best kids bikes have kid-sized and adjustable-reach levers, as well as appropriately sized cranks, saddles and handlebars.

This table shows the various bike wheel sizes and the approximate ages they are suitable for, as well as the minimum height and inseam length for each wheel size. Please note, the important thing here is the size of the child, not the age.

Approx age Wheel size  Minimum inseamMinimum height
  Inchescm  Feet/Inches cm
2+ Balance (12in)12in30cm2ft 8in88cm
3+  14in15in38cm3ft 3in98cm
4+ 16in16in42cm3ft 5in104cm
5+ 18in18in 46cm3ft 8in112cm
6+ 20in20in52 cm3ft 11in120cm
8+ 24in23in57cm4ft 2in127cm
10+ 26in25in 64cm 4ft 7in140cm

12in wheels – balance bikes – ages 2+

These are the small push-along bikes that were made popular in Scandinavia. They generally don't have pedals, and this encourages a child to learn balance and to push the bike along under their own momentum.

Balance bikes come in a range of materials, but we'd recommend a metal frame model with pneumatic tyres. The laminated wood balance bikes do not last well when regularly exposed to cold or wet weather.

A balance bike like this strider is a great introduction to riding bikes. by teaching balance and bike control separate from pedaling and braking, a balance bike can allow a child to skip training wheels when they move to a pedal bike: a balance bike like this strider is a great introduction to riding bikes. by teaching balance and bike control separate from pedaling and braking, a balance bike can allow a child to skip training wheels when they move to a pedal bike
A balance bike like this strider is a great introduction to riding bikes. by teaching balance and bike control separate from pedaling and braking, a balance bike can allow a child to skip training wheels when they move to a pedal bike: a balance bike like this strider is a great introduction to riding bikes. by teaching balance and bike control separate from pedaling and braking, a balance bike can allow a child to skip training wheels when they move to a pedal bike

Balance bikes teach kids balance and handling before pedals and brakes are introduced

14in/16in wheels – first proper pedal bikes – ages 3+

Once they've mastered a balance bike, it's time for your child to move onto a bike with proper pedals. Pedal bikes designed for younger children tend to have 14in or 16in wheels, and can be fairly heavy for their size. If your child has gotten the hang of balancing without pedals, coasting along on a balance bike, they will likely be able to make the jump to pedal bikes without training wheels.

When buying a 14in or 16in wheeled bike, as with any bike, consider proper fit. Although it can be tempting to buy a bigger bike with the thought of them growing into it, this will compromise their ability to ride safely and enjoyably. Make sure they can easily reach the handlebars and stand over the bike.

In the US, kids bikes of the size must have a pedal brake by law. In the UK and Australia, however, you can look for bikes with rim brakes.

14in bikes require and inseam of 15in / 38cm: 14in bikes require and inseam of 15in / 38cm
14in bikes require and inseam of 15in / 38cm: 14in bikes require and inseam of 15in / 38cm

A proper first bike with pedals will usually have 14in or 16in wheels. Milo here fits on a 16in Islabike

20in wheels – introducing gears – ages 6+

The move to 20in will likely be the first time your youngster will have a bike with gears. Typically 20in bikes have a single chain ring at front with a twist-style shifter for a few gears in the back.

In the US, this is also the first kids' size bike to have a rear rim brake.

Most 20in bikes require and inseam of 20in / 50cm: most 20in bikes require and inseam of 20in / 50cm
Most 20in bikes require and inseam of 20in / 50cm: most 20in bikes require and inseam of 20in / 50cm

20in bikes add gears to the mix, as well as rim brakes front and rear

Check out our test of 20in kids bikes here.

24in wheels – versatile bikes for longer rides – ages 8+

Whether your child is riding on the road or off, a versatile 24in wheel bike covers ground and deals with bumps better than a 20in. Suddenly, you’re measuring rides in miles, not minutes.

Bikes start to get serious around this wheel size. As with all kids bikes, you should be looking for properly sized components, such as cranks, grips, brake levers and handlebars.

24in bikes require an inseam of 23in / 57cm, and can be ridden by children as young as seven:
24in bikes require an inseam of 23in / 57cm, and can be ridden by children as young as seven:

Just like an adult moving from 26in to 29in wheels, a kit going from 20in to 24in will gain efficiency

26in wheels – sized-down adult bikes – ages 10+

The original mountain bike wheel size is also the final stepping stone to full-sized road bikes. Using smaller 11, 14 and 15in frames, both road and mountain bike models are available in this category.

They're essentially scaled-down versions of the adult bikes, and nearly as fast and practical. There’s a big selection of style and prices to choose from when you reach 26in wheels.

26in wheels used to be the standard adult-sized mountain bike wheel. now they are a great size for preteens and most teenagers:
26in wheels used to be the standard adult-sized mountain bike wheel. now they are a great size for preteens and most teenagers:

26in wheels used to be the standard adult-sized mountain bike wheel. Now they are a great size for preteens and most teenagers

700C / 650b / 29in – the big time

These are the biggest wheels used in cycling, and can be suitable for older or taller children with the right sized frame. 650b is a mountain bike wheel size that falls between 26in and 29in and is often (inaccurately) referred to as 27.5in. 700C is a road bike size, essentially the same 29in.

It's 700c on this boardman junior road bike:
It's 700c on this boardman junior road bike:

It's 700C wheels on this Boardman Junior road bike

For more on all of this, see our video series below

This article was originally published in Cycling Plus magazine, available on Apple Newsstand and Zinio.

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