Kids' bike buyer's guide

Kids’ bikes are all about having fun, making memories, and giving your child the kind of freedom only found on two wheels. It’s amazing to see your child ride for the first time, head out together on a family cruise, and watch them grow as a rider. Whether your little one is ready for their first bike ever or a bigger size, our guide will help you make the right choice. Happy riding!

What size bike does my child need?

In general, the size that’s right for your child depends on their age and height. Our biggest piece of advice? Don’t buy a bike that’s too big for your child, thinking they’ll grow into it. It can slow down their learning and affect their confidence. The right size bike makes your child feel comfortable and is a lot easier for them to maneuver so they can pick up skills fast. Some companies even offer programs that let you trade in outgrown bikes, which brings the cost down so you can always have a bike that fits your child. Here are some tips for helping you find the best-fitting (and most fun) bike for your child.

Kids' bikes are measured by wheel size instead of frame size

Adult bikes are measured by frame size, but kids’ bikes are measured by wheel diameter. Sizes range from 12” to 26”, for the smallest children to the tallest.

Age and height help determine a size bracket

Your child’s age and height will help guide you to the right wheel size. Measure your child, then check out the sizing guidelines below to find their potential wheel sizes.

Knowing their inseam helps find the best fit

Once you have an idea of wheel size, consider measuring your child’s inseam, too. Knowing this will really help you find a bike that’s comfortable for them to stand over and hop on and off.

Kids’ bike size chart

Size brackets are wide and tend to overlap, plus all bikes fit differently (even if they’re the same wheel size) so head down to your local bike shop with your child for some fun test rides! Pro tip: if your child is older than 12 and/or taller than 4’ 8” you can start looking at adult bikes.

Bikes for 2 and 3 year olds

Height: 3’ 0” - 3’ 3”
Inseam: 15” - 18”
Wheel/bike size: 12” (balance bike or training wheel bike)

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Bikes for 4, 5, and 6 year olds

Height: 3’ 5” - 4’ 0”
Inseam: 16” - 22”
Wheel/bike size: 16”

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Bikes for 5, 6, 7, and 8 year olds

Height: 3’ 9” - 4’ 6”
Inseam: 19” - 25”
Wheel/bike size: 20”

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Bikes for 8, 9, 10, and 11 year olds

Height: 4’ 1” - 4’ 11”
Inseam: 23” - 28”
Wheel/bike size: 24”

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Bikes for 10, 11, and 12 year olds

Height: 4’ 8” and up
Inseam: 25” and up
Wheel/bike size: 26”

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Adult bikes for older kids

A lot of older, taller kids can fit on the smallest adult bikes. When you go looking for an adult bike, remember that they are sold by frame size and not wheel size!

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How should a kids' bike fit?

A bike that fits well is easier for learning to ride, and ultimately more enjoyable for your child from day one. Generally, you’ll know you have the right fit if your child is feeling confident and excited on the bike. Below are some visual fit cues that’ll help you decide whether or not a bike fits your child properly. Be sure to look for these fit cues not only when you test ride bikes at the shop, but also as your child grows and gains skills.

Seat height

It’s important to have your child’s seat set at the right height. You’ll continue to adjust it as they gain skills and confidence, too. Generally, for balance bikes and for their first non-training wheel bike, your child’s feet should be flat on the ground while they’re seated. For training wheel bikes and for riders comfortable on pedal bikes, only their toes should be able to touch the ground.

Knee position

Knee position is directly related to seat height. When kids are just learning, they should have more bend in their knees so they can easily put their feet on the ground. This gives them more on-bike confidence. As they feel more comfortable, you can raise the seat up so they can get full leg extension for better pedaling.

Standover height

You’ll want to make sure your child can easily stand over the bike with their feet on the ground, and with an inch or two between them and the top tube of the bike. This helps them feel confident stopping and getting on and off the bike.

Foot position

When kids are starting to learn on a balance bike, their feet need to touch the ground so they can propel the bike. For training wheel bikes or pedal bikes, your child will be most comfortable with the ball of their foot resting flat on the pedal.

What’s the best kids’ bike to get my child?

There are lots of kids’ bikes to choose from, so narrowing down your options can be hard! The main thing is to ensure the purpose and features of the bike match your child’s skill level. For example, most young kids will likely only ride short distances around the neighborhood. They benefit from a simple, hybrid-style little kids’ bike without unnecessary features. As kids get older and gain more skills, they’ll be able to choose from several types of bikes with many different kinds of features. Pro tip: girls’ bikes and boys’ bikes are essentially the same, they just might have different colors or graphics.

Kids’ hybrid bikes

These bikes are awesome for all-around riding. They are designed for comfort and confidence on every ride, whether on roads, light gravel paths, or even detours through the lawn. They're typically equipped with tires designed for traction on a variety of surfaces.

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Kids’ mountain bikes

Some kids’ bikes have rugged styling but are still meant to be ridden on pavement. True youth mountain bikes are designed specifically for off-road riding. They have parts designed to handle bumps, rocks, and dirt—like knobby tires and, on some models, suspension forks. If your child has the advanced handling, shifting, and braking skills necessary to properly use a complicated bike, and shows an interest in hitting the trail, it might be time for a kids’ mountain bike.

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What is a kids’ balance bike?

Balance bikes are like a cross between a scooter and a bicycle. They’ve become popular in recent years as savvy parents have recognized that balance, not pedaling, is the most important part of riding a bike and should be the starting point of any instruction. Balance bikes don’t have pedals, which allows small children to push themselves along using their feet and practice balancing their weight over the bike. They’re the best bikes for toddlers, and teaching kids to balance early on will make their transition to a bike with pedals much easier.

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What about kids’ bikes with training wheels?

You probably learned to ride by using training wheels, and most professional cyclists probably did, too. Training wheels are a great way to get kids comfortable riding, and to get them hooked on the feeling of freedom that only a bike can provide. They’re a good choice for kids who are too big for a balance bike or simply need a bit more time to gain confidence.

Pro tip: when teaching your child to ride, remember that the emphasis should be on balance, not pedaling. As soon as your child is comfortable with the thought of removing their training wheels, it’s time for them to go!

What's with these different kids’ bike brakes?

As kids gain riding skills, the bikes available to them will have more brake options. You want to start them off with no brakes (balance bikes) or a coaster brake (the kind of braking that engages when you pedal backwards) because it’s intuitive to put your feet down or pedal backwards to stop. Once they are comfortable stopping themselves using these brakes, and have more developed muscles in their hands, they can upgrade to hand brakes. Some kids’ bikes even have both a coaster brake and hand brake so kids can start getting comfortable with them sooner.

Should my kids' bike have gears?

Not at first! It’s most important that kids learn how to balance and pedal properly. This is why beginner bikes typically have just one gear. As they gain bike handling skills, confidence, and hand strength, you can upgrade them to a kids’ bike with a few gears. This will help them get comfortable with shifting, which they’ll of course need to know how to do as they continue to ride more complicated bikes. In the end, the ideal gearing for your child depends on their skills and the type of riding they’ll be doing. Gears significantly increase a bike’s versatility and reduce fatigue so that your child can participate in longer rides with the family, or better tackle variable terrain.

What else does my child need?

Definitely a helmet! It’s important for your kid’s on-bike safety and it teaches them that riding safer matters. We also always recommend front and rear lights on every ride to help them stand out, and you can also add fun stuff like baskets and handlebar bags. There’s also lots of options out there for having fun riding as a family, no matter if your child is of riding age or not!

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Why choose a Trek?

We want your kids to enjoy biking just as much as you do, so we put the same amount of dedication and know-how into their bikes as we do yours. This matters because learning to ride on a well-designed bike is both easier and more enjoyable, and when your little one loves riding as a kid they'll love riding forever. Each one of our kids’ bikes is made with durable, high-quality materials and assembled by a professional mechanic so you can focus on having fun with your little ones for years to come.

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