Kids’ Bike and Helmet Sizing 101

evelyn murcia event and outreach coordinator arlington county
Evelyn Murcia Tweet Us @bikearlington@bikearlington October 1, 2019

Evelyn Murcia is the Events and Outreach Coordinator for Active Transportation. She enjoys riding her bike year round on Arlington’s trails and streets. She also enjoys wrenching on bikes from time to time.

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Is your child interested in learning how to ride a bike or have they outgrown the one they ride now? Picking the right size bike and helmet may seem like a challenge but we're making it easy for you. Get the scoop!

Every child is different especially when it comes to picking out the right size bike. What may work for your five-year-old child may not work for another child of the same age, since there are a lot of factors that determine what size bike will fit best. So, we’re giving you some insight into what size bike fits for certain ages and heights and what your kid needs to be able to ride comfortably. A well-fitting bike will make the ride pleasant and encourage your child to ride. 

parent and child riding bikes

Choose the Right Size Bike

When looking for a bike for an adult, you choose it based on the frame size. But with kids’ bikes, you choose one based on the wheel size which ranges from 10 inches to 26 inches. A great way to measure if a bike fits is by the inseam size. For children starting out, you want them to be able to place their feet flat on the grounwhen on the saddle and with experience you can bring it up as they get more comfortable on the bike (once pedals are introduced). 

10-Inch Bike 

A 10-inch wheel or smaller is the size you’d find on tricycles and some balance bikes. 

Age Range: Two years and under 

Height: approximately 2’8” or less 

12-Inch Bike 

12-inch bikes include both balance bikes and pedal bikes. Balance bikes are really simple, because they don’t have pedals or brakes. They’re push bikes to help a child learn how to control and maintain balance without the use of training wheels. Pedal bikes have one gear, pedals, and a coaster brake (pedal backward to stop) and can be used once your child has mastered the balance bike. You can also add training wheels to a 12 inch pedal bike if your child is really struggling. 

Age Range: Two to four years old  

Height: approximately 2’8”-3’4” 

14-Inch Bike 

A 14-inch bike is less common but is a good in-between size bike if your little one is a really tall three or four year old. You will also notice that these bikes usually have pedals, one gear, and brakes. Some are used as balance bikes for those who are a little older and too big for a 12 inch size bike. 

Age Range: Three to five years old 

Height: Approximately 3’1”-3’5” 

16-Inch Bike 

16 inch bikes tend to be pedal bikes with one gear and either coaster brakes or hand brakes. These are great for kids going short distances like riding around the block or on the trail with family.

Age Range: Four to seven years old 

Height: Approximately 3’4”-3’10” 

18-Inch Bike 

An 18-inch bike is another less common size but works great as an in-between size. They’re more commonly found in stores like Walmart and Target. 

20 Inch Bike 

20 inch bikes tend to have one to two hand brake levers. These bikes have gears that your child can use if they’re ready to go longer distances like riding to school, going on rides with hills, or keeping a faster pace. 

Age Range: Six to nine years old 

Height: approximately 3’9”-4’4” 

24-Inch Bike 

24 inch bikes are for children not quite ready for an adult size bike but are ready to ride to school or with friends on a bike that looks like a mini adult bike. These bikes have both front and rear brakes with gears in the back and sometimes in the front. 

Age Range: Nine to 12 years old  

Height: Approximately 4’5”-5’ 

26-Inch Bikes and 650b Bikes 

26 inch bikes are adultsized bikes that are usually measured by frame size but will fit taller 12-yearolds. For kids around 4′ 10”, look for an extra small or small frame usually about 13 to 15 inches. 650b bikes are usually road/cross bikes for youth with smaller wheels than the usual 700c wheel on adult bikes 

Age Range: 12 and up 

Height: Approximately 4’10” and up

Choose the Right Helmet

Now that you’ve picked the right size bike for your child, it’s a good time to get a new helmet or check the fit of their current helmet to protect their precious noggins. It’s also important to remember that children ages 14 and under are required by Virginia law to wear a helmet when on a bike. 

Follow these steps to check for a properly fitting helmet:

  • The child’s head should be completely covered, and the helmet should not wiggle back and forth.
  • Make sure there is a two–finger width space between the helmet and eyebrows as well as under the chin between the strap.
  • The helmet straps should follow a peace sign right below the ears.

Take Your Child for a Ride

Now that you’ve picked a bike for your minime and checked their helmets for proper fitting, now it’s time to go for a ride. Join us for the family-friendly events throughout the year. 


Photo Credit:

Sam Kittner/

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