How We Size A Kid’s Bike at The Bike Room

It’s exciting buying your child their first bike. It’s a real milestone for them and you. But how do you know what size bike to buy? We stock Frog Bikes (among other brands) and we use their sizing guide to get your child cycling on the right bike. 

Frog Bikes for Kids at The Sports Room, Wicklow TownIn contrast to many kids’ bikes, the Frog range of children’s bikes we stock are sized by the leg length rather than age, as this is the most reliable way of getting the right size of bike for each child. Age alone isn’t a reliable measure as there is a large spread of “normal” leg lengths & heights for each age.

Why not drop in and some get help and advice on sizing? Try a Frog Bike out…

If you can, bring your child into The Bike Room at The Sports Room. We will take the time to measure the rider’s inside leg in cm and size the bike correctly  to match their height allowing for growth. We will recommend the bike that matches the inside leg length, with the saddle at its lowest setting. At this height, the child will safely and comfortably be able to get their feet on the ground. Don’t worry – Frog Bikes have long seat posts, so the saddle can be raised a long way as the rider grows. Don’t be tempted to buy a bike that’s too big in the hopes that they will grow into it – it’s not safe and they’ll lose confidence.

Not able to bring your child into The Sports Room?

Don’t worry – try this simple measuring trick at home. Ask your child to stand against a wall. Place a book between the legs, as high as is comfortable, and mark the wall where the top of the book rests. Measure in cm from that point to the floor. That is the measurement of the inside leg. Bring that measurement down to us and we’ll help you choose the right bike for your child.

Frog Balance Bikes at The Sports Room, Wicklow TownThe Frog range starts from age 2 with balance bikes to first pedal bikes and cover hybrid and road bikes right up to age 14. Our own children all started out with balance bikes at aged two. It’s a great way to get the younger children joining in a family cycle as they find it easier to keep up than on a bike with stabilisers. If your child is too big for a balance bike, buy them a lightweight frog bike and take the pedals off. Once they have the hang of it, pop the pedals back on after a few weeks and watch them go!

Need a helmet?

Getting the right size helmet for a child is important too. To measure, wrap a measuring tape around the child’s head, above the eyebrows and measure in cm. Most children will need a S (52-58cm) or XS (46-53cm). Kids over 10 years of age usually need an adult helmet. When the helmet is on it shouldn’t move when the child shakes their head. Helmets should not be worn tilted back. The rim should sit on their forehead.

When should you service the bike?

Lightweight children's bikes from Frog at The Sports RoomBring your bike back to The Bike Room after six weeks and Enda will fine tune it for you, for free. The bike should be serviced once a year after that. All Frog Bikes come with a 2 year warranty on frames, forks, parts and paintwork. If you register your purchase online, you can increase this to a 5 year warranty. Sounds good.


At The Bike Room, in The Sports Room, Wicklow Town, we service and repair bikes. We sell a wide range of childrens’ and adult bikes from brands like Frog, Giant, Pivot, Stanton Bikes and more. We also stock biking accessories, road bike apparel and bike parts. We specialise in mountain biking and stock brands such as Fox MTB, Five Ten Shoes, Endura and more…