How to choose the right BMX bike size for your child
When buying a BMX bike for a child, the most important thing is choosing the correct size for their height. From experience, it is not a good idea to buy a BMX “to grow into”. A bike that is too large will make riding and learning tricks much harder.
BMX bikes are designed specifically for tricks, jumps and skatepark riding. They are naturally smaller than regular bicycles. That is why when you see someone riding a BMX, the bike may look slightly undersized. This is completely normal and part of how BMX geometry works.
A BMX bike for tricks should be compact, lightweight and responsive. This setup gives riders better control and makes learning new tricks much easier. However, this does not mean you should buy a BMX without checking the correct size first.
A properly sized BMX bike is already half the success. The other half comes from regular practice and proper protective gear.
What BMX bike sizes are available for kids?
Kids BMX bikes are available in wheel sizes from 12 inch up to the standard 20 inch BMX.
12 inch BMX bikes are designed for the youngest riders who are just starting to ride. Children from around 90 cm to about 120 cm in height can comfortably use this size. Even a three year old can start riding their first BMX.
The next option is a 14 inch BMX. This size works well for children roughly between 110 cm and 125 cm tall.
16 inch BMX bikes are usually suitable for riders between 120 cm and 135 cm. A seven or eight year old rider will often feel very comfortable on this size.
18 inch BMX bikes are typically chosen for riders between 135 cm and 150 cm in height.
If you are wondering about 20 inch BMX bikes, this is the standard size used by teenagers and adults. Riders from around 145 cm tall usually move to a 20 inch BMX.
How to choose the correct BMX size
Use the table below as a guideline to match a BMX bike to the rider’s height. Choosing the correct size will make riding more comfortable and learning tricks much easier.
| Approximate age | Height | Wheel size | BMX frame size |
|---|---|---|---|
| 3–5 | 90–110 cm | 12" | 12" |
| 5–7 | 110–125 cm | 14" | 14" |
| 7–9 | 120–135 cm | 16" | 15"–16" |
| 9–11 | 135–150 cm | 18" | 18" |
| 10–12 | 145–160 cm | 20" | 19.5"–20.25" |
| 11–13 | 150–168 cm | 20" | 20"–20.5" |
| 13–15 | 160–175 cm | 20" | 20.25"–20.75" |
| 15–17 | 175–183 cm | 20" | 20.75"–21" |
| 17+ | 180+ cm | 20" | 21" |
Data based on RMDBike experience and thousands of BMX bikes sold. Age is only a guideline. Rider height is the most important factor when choosing a BMX.
If you are close to the boundary between two sizes, it is usually better not to choose the larger option. Crossing a height threshold does not mean the bike suddenly becomes too small. Most riders will comfortably use the same BMX size for a long time.
Keep in mind that larger frames usually mean heavier bikes. If a rider has a smaller build, every gram matters. Weight can affect how easily the rider can lift the bike and perform tricks. Body proportions also matter, including arm and leg length. A larger bike does not always mean a more comfortable riding position.
BMX riding is a great way to develop balance, coordination and enjoy time outdoors. If you are still unsure whether the BMX you selected is the right choice, feel free to contact us. Our team will help you choose the right bike.
