• Injury Prevention Program
Boy wearing helmet on bicycle


The weather is great and it’s a good time to get out and pedal your way to some fun. This last year has been different and bike shops have been busier than ever before. If you have been in a bike shop or major store, bikes and bike accessories are in short supply. More folks are home, which means more adults and children are out riding bikes. At Phoenix Children’s, we’re always concerned for the safety of children, throughout our communities.


April is Arizona Bike Month and we know there will be lot of activities all around the state and our local communities (for information about AZ Bike Month, click here). 

Stay tuned to the Phoenix Children’s Bright Futures blog throughout April as we explore these three main areas of bike safety:

  1. How to fit your child(ren) with the right bike
  2. How to pick the right bike helmet
  3. The importance of following “the rules of the road”

Bike fitting

Learning how to ride a bike can be a significant milestone in a child’s life, but before you wipe off the dust and strap on their helmet, you need to find them the perfect sized bike. Bikes that are too large or too small can be difficult to control and maneuver. We see too many kids’ injuries because the bike they were riding was too big for them and they could not handle its size. Therefore, understanding what size bike to purchase can be crucial to a child’s experience.

So, how do you know what size bike is right for your child? Unlike adult sizing where the bike frame determines the size needed, the wheels on kids’ bikes set the proportions. Bike wheels start small with one-size balance bikes for toddlers. Meanwhile, wheels that are 24 inches in diameter are considered the last step before moving up to adult models.

Below is a bike size chart categorized by height, age, wheel size and a picture of what that bike might look like. It’s important to keep in mind that a test ride is the best way to get the most accurate fit.

Bicycle Size Guide

Both age and height are important considerations. The best size bike for a 4-year-old is either a 12-inch or 16-inch wheel depending on their height. Similarly, the right size bike for a 5-year-old falls into that same range.

Most 8 and 9-year-olds will fit on a 20-inch wheel bike. Meanwhile, a 10-year-old (or older) will likely use the 24-inch size. Keep in mind that if your 10-year-old is smaller, they may still be more comfortable with a 20-inch bike wheel. Older children may be looking at a 24” bike.

It might be tempting to buy your child a bike he/she can “grow into” over time. However, doing so is ill-advised. Again, we see too many injuries due to bikes being too large. A bike that is difficult to maneuver could impact their confidence and make it harder for them to learn in the future as well.

To account for small growth spurts, some bikes enable you to raise the seat and the handlebar stem for minor customizations in size. However, be sure to check the limits on the owner’s manual of whatever bike you choose. If adjustments don’t solve problems with comfort and function, then it’s time to move up to the next size level.


Our next bike safety blog will be on the importance of wearing a bike helmet, plus how to choose one and wear it appropriately. 


Happy bike riding!