Bike Sizing Guide – Kids’ Bikes

Frog 52When choosing a child’s bike you are looking to balance a number of factors.

  • You want a bike with plenty top tube (crossbar) clearance so your heir can safely hop off the saddle and straddle the crossbar with both feet flat on the ground.
  • You want a bike that’s easy to manage (1). Just as you don’t want a bike that’s too big crossbar-wise, you don’t want a bicycle that’s too long. A bike that’s too long is unwieldy, harder to control and harder to steer. That’s, incidentally, why tyre size determines child bike fit. A bike with 12″ wheels will not only be shorter in height than a 16″ wheeler, it will also be shorter in length.
  • You want a bike that’s easy to manage (2). Every serious adult rider knows that a lightweight bike is more likely to be a joy to ride than a heavy bike. This is even more true for younger riders just building their strength. This is worth remembering when choosing between one of our 12 kilo junior MTBs against a 25 kilo full suspension supermarket special.
  • You want a bike that will last as long as possible – i.e. look for a bike that’s small enough to straddle, yet big enough to offer years of growth, and well built enough to pass on to a wee brother or cousin in years to come. Look for a bike from a brand name that cyclists recognise and respect.

Children’s Bikes Size Guide

Children’s bike sizes are determined by wheel diameter (not frame size like adult bikes).

Obviously your child’s personal growth spurts might invalidate these guesstimates so, like any size chart, please regard this as a rough guide. For example, while the majority of 5-10 year olds fit 20″-wheeled bikes, the smaller 5 year old might not manage one and would be safer on a 16, while the taller child might outgrow the 20 inch wheeler and will require a 24 incher by the time he or she is 8.


Balance bikes for 2 – 4 years olds

No pedals, no cranks and no brakes enable the young rider to learn how to balance and steer with minimum distraction.

12 inch-wheeled bikes for 3 – 5 years olds

These petite bikes are mountain bike styled. Fat tyres = stability. Removable stabilisers can be confidence builders. Single speed gear-free transmissions keep life simple.

16 inch-wheeled bikes for 4 – 7 years olds

Again single-speed MTB styled, with or without stabilisers: it’s with the 16″ wheeler that the child often graduates from play/pavement bike mode to serious adventures such as rides through the park and pedalling to school.

20 inch-wheeled bikes for 5 – 10 years olds

Now we’re getting serious. 20-wheeled MTBs (mountain bikes) boast suspension forks to smooth the bumps and 5 or 6 gears to smooth the climbs.

Not interested in changing gear, more interested in play? Then consider a BMX. BMXs are 20 inch wheelers (bar the odd 16 incher for smaller riders) that fit near any rider from around 10 years old.

24 inch-wheeled bikes 8 – 14 years olds

Front or full suspension; triple chainset transmission with 15 / 18 / 21 / 24-speed gears: these really are scaled-down MTBs, fit for the trails.

26 inch-wheeled bikes 11+

A 26″ wheeler is of course an adult-sized MTB. Some adult MTBs are available in very small sizes. For instance, you can get a Specialized Hardrock with a 13″ frame which kids as young as 11 can manage. The obvious advantage with this size is the much wider choice of spare parts (the number of 26″ tyres on the market outnumbers 24″ tyres at least 100 to 1). Another advantage is that spare tubes, for instance, can be pooled on family rides.

Need to know more?

Phone 0845 257 0808 (low call) or 0131 331 5010 to speak to someone in our online team who can give you more helpful advice about buying a kids’ bike.