Guide To Kids Bike Sizes

Are you struggling to figure out what size kids bike should I buy? Read our guide to kids bike sizes to get all the answers you need.

Kids’ bike sizes are a lot easier than adult bikes. With adult bikes, it is the frame that is measured and this can be done in inches, centimetres or simply small, medium and large, depending on the brand. With kids bikes, everyone measures them using the size of the wheel. So, when you see a kids bike referred to as a 12” or 20” it is the wheel size they are talking about.

Working out what size of kids’ bike a child needs is normally done on a combination of their age and height. The exact sizing will vary slightly depending on the bike but as a rough guide you can use the following:

size3 to 4Under 100cm12”
4 to 5100cm to 120cm16”
6 to 8120cm to 135cm20”
8 to 12135cm to 145cm24″
Once a child is over 145cm (5 feet) they can start moving onto small and extra small adult bikes. If they are aged 2 to 3 (or under 80cm) then a Balance bike is a good option. There is no difference in sizing between most boys and girls kids bikes.
In Store Sizing

Of course, the best way to find the right kids bike size is to visit one of our stores. Each Cycles UK store keeps a range of children’s bikes in stock for your child to try out. Of course, if the bike is going to be a surprise or you are not close to a Cycles UK shop you can use the size charts on this page to find the size you need.

All of the children’s bikes that we sell come with some adjustments in the sizing. The seat on all bikes can be raised or lowered to accommodate children of different heights and many bikes have adjustable handlebars. This allows the bike to grow with your child and ensures it will last a good couple of years.

Brand Sizing

Pretty much all of the big cycle brands have their own way of measuring and sizing bikes. On kids bikes, there is not a huge amount of difference but if your child is on the border between a wheel size it is worth checking a particular brand’s recommendations. To help you do this we have included the sizing charts 

for three of our main kid’s bike brands below.

Specialized Kids Bike Sizes
Height (cm)8182-9495-104105-119120-142
Height (Inches)3232-3737-4242-4747-56
Wheel SizeBalance
Trek Kids Bike Sizes
Height (cm)91-102100-118115-133130-151148-160
Height (Inches)3″-3’4″3′ 3″-3′ 10″3’9″-4’4″4’3″-4’11”4’10”-5’3″
Wheel Size12″16″20″24″26″ (650c)
Raleigh Kids Bike Sizes
Wheel SizeMin Rider HeightMax Rider HeightAge
26″129cm147cm9, 10, 11