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Kids' Bike Sizing Guide

Growth Spurts Happen. We Can Help.

At Black Mountain Bicycles, we believe that cyclist of all ages should enjoy a bike that is safe, lightweight, correctly sized, and fun to ride. Learn more about our kids' bike selection and all of the incredible features and benefits that come standard when you take home a kids' bike from Black Mountain Bicycles. 

Kid's Bike Size Chart

Balance Bike12" Wheel16" Wheel20" Wheel24" Wheel26" Wheel
AgeUp to 3 yrs2.5 - 4 yrs3 - 6 yrs5 - 8 yrs7 - 10 yrs9+ yrs
Height30" - 35"35" - 40"39" - 46"45" - 52"51" - 63"62"+
Inseam15″ – 18″15″ – 20″16″ – 22″19″ – 25″23″ – 28″25″ +

Note to parents: Our kid's bike size chart is just a starting point. 

Every child is different and while you can get in the ballpark with this info, you'll want to make sure your kid gets a chance to try out the bikes you're considering. 

Find the right bike for your child

Choose the Right Bike

When your child rides a bike that is too small or too large, it is both uncomfortable and unsafe. Our friendly, trained staff is here to help you select the size that fits your child, to make the necessary adjustments, and to ensure that you and your child love your new bike.

We have the best selection of kids' bikes

Why Shop with Us?

When you buy a bike from us, you're giving your child a quality product that’s lightweight, well-built and properly sized. Your young cyclist will love the new ride. And, you’ll feel great knowing that you’ve invested in a professionally-assembled kid's bike.

Stay safe with the right kids' helmet

Safety Comes First

Not only does your child's bike come professional assembled, but we offer a free 60 day tune-up, plus 1 year free safety adjustment to ensure it is rolling along the driveway and sidewalks properly. We also carry a great selection of kids' helmets, training wheels, bells to keep your little one safe while they are the go!

Common Kid's Bike Questions

How are kid's bikes sized?

Unlike adult bikes that are sized by the frame, kid's bikes go by wheel size (diameter in inches). The most common sizes are 12", 16", 20", 24", and 26". Refer to the size chart above for more info.

How do you determine bike size for a child?

If your child already has a bike, see if there are any stickers that say what size the wheels are, look up the make and model, or just measure the diameter of the rims (not the tire).

If you're buying your kid their very first bike, start with the size chart above then dig into the other info on this page. Finally, the very best thing to do is have them try out a few options!

How do you know if a kid's bike fits well?

When it comes to making sure the bike isn't too big, having enough standover height is key. When your child straddles the bike while standing (not sitting), they should have a little clearance over the top tube. 

If you're trying to decide if the bike is too small, look at how bent their knees are when they pedal. If the seat has raised (but not past the max insertion limit) and their knees are constantly bent while pedaling, they probably need a bigger size.

Is it okay to size up on kid's bikes?

It's ok to size up as long as your child can still comfortably ride the bigger size. We get it, bikes aren't cheap and some kids outgrow things pretty quickly. But buying a bike that's way to big just so they can grow into it doesn't make much sense, as a poorly fitting bike can make it hard for them to ride, resulting in potential crashes (not to mention the risk of them giving up on bikes altogether).

What should you do if a child is in between kid's bike sizes?

If your child is between sizes on our bike size chart, the best thing to do is bring them in to try out some models. You can tell pretty quickly if the big bike is too big or uncomfortable. That being said, if they feel fine riding the bigger bike and they have enough standover room over the top tube, they should be able to grow into the bigger model just fine.

What age do kids start learning to ride bikes?

That's totally up to you and them! Most kids start to learn between the ages of 3 and 8, but we know some bike lovers that get their children on balance bikes as soon as they can walk. Generally speaking, the older kids get the more challenging it can be for them to pick it up quickly. Our advice is to start 'em young while they have no fear and are up for trying new things.

How do you teach a kid to ride a bike?

Teach balance and confidence first, then bring in the pedals. What does that mean? Well, training wheels can be more of a handicap and can make the transition worse down the road, so we recommend trying to avoid them as best you can. 

Balance bikes are great if your child is young enough to ride a 12" bike. Some bigger bikes come with the ability to take the pedals and cranks off and we recommend doing that if you're able to. 

Get them comfortable scooting around with their legs, then once they start to lift both legs up and coast you'll know they have enough balance to transition to pedals.

Balance bikes are the best way to get kids comfortable on bikes at an early age. If this will be their first bike and they're 3 years or younger, balance bikes are the way to go. 

The idea is simple: get them comfortable scooting around on two wheels without pedals to work on balance and confidence. Their transition to pedals will be much smoother once they have a solid foundation.

16-Inch: 3-6 Years Old / 39-46" Tall

16" bikes are a step up in wheel size from the smallest size but can still be ideal for kids who haven't learned to ride just yet. These models usually come with removable training wheels and feature typically feature coaster brakes and just one gear for simplicity. 

20-Inch: 5-8 Years Old / 45-52" Tall

20" kid's bikes are usually great for 5-8 year olds and the models start to have more options in terms of brakes and gears. Since kids this age can vary greatly in their comfort on bikes, you'll find that 20" models have single speed coaster brake versions, versions with hand brakes and gears, and even suspension.

24-Inch: 7-10 Years Old / 51-63" Tall

24" kid's bikes are the last "child" size but they typically fit the widest range of kids, usually from 7-10 years old or older. These models often feature gears and hand brakes, with off road versions sometimes coming with suspension.

26-Inch: 9+ Years Old / 62"+ Tall


26" inch wheels used to be the standard for cruisers and mountain bikes, but nowadays they're often tailored to kids who are right in between kid and adult sizes. If your child has outgrown their 24" bike but isn't quite ready for an adult bike, 26" models are the way to go.