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.
- Related reading:BikeRadar's guide to buying kids' bikes
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 inseam||Minimum height|
|2+||Balance (12in)||12in||30cm||2ft 8in||88cm|
|6+||20in||20in||52 cm||3ft 11in||120cm|
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.
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.
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.
20in bikes add gears to the mix, as well as rim brakes front and rear
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.
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
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 wheels on this Boardman Junior road bike