Kids Bike Sizes: A Parent's Guide to Finding the Perfect Fit

Published October 26, 2021
Boy riding a bike with his dad

Buying a bike for your child is an exciting rite of passage in their childhood years. When it comes to finding the best bike for your kid, you may be perplexed by the many types of bikes and by the various sizing guidelines. Make sure you know exactly what to look for when selecting a child-sized bike, so you and your kid can enjoy countless rides together.

Kid's Bike Sizes: They Are Not One-Size-Fits-All

When deciding on which bike to purchase for your child, you must consider several factors. Walking into the store and announcing you need to buy a bike for a five year-old will probably leave you with more questions than answers, and no bike to take home. Prepare ahead of time by noting the following:

Wheel Size Matters

A bike's wheel size serves as a starting point for finding a correctly sized bike for a child. Make sure you take into account the height and age of your child, and match those attributes to the different-sized wheels found on children's bikes. Wheel sizes provide a general guide to begin with, but simply looking at wheel size won't give you a complete picture of what makes a well-fitted child's bike. Several more factors should be addressed after a general wheel size is determined.

father helping daughter choose bicycle in shop

Bike Wheel Sizes

Look for these wheel sizes to accommodate children in the following different age categories:

  • Children ages two-four: 12 inches
  • Children ages three-six: 16 inches
  • Children age seven and older: 20 inches
  • Children age 10 and older: 24-26 inches

Know Your Child's Height and Inseam

Height is very important when purchasing a best-fitting bicycle for your child. If your child is five years-old, but very tall for their age, you may want to go up in wheel size. Vice versa, if your 10 year-old is super tiny, look to other factors rather than simply wheel size to make sure their bike fits properly.

Aside from general height, measure the inseam of your child as well. The inseam is the length in measurement of the entire leg. Knowing this measurement can help choose a bike frame that suits a child best, and it is this measurement that is often regarded as the most important one when determining bike fit.

Pedal Bike vs. Balance Bike

Young children have two primary options when it comes to bicycles: pedal bikes and balance bikes. Balance bikes are for kids who are just starting to ride a bike, but are not ready to take on pedaling. They do not include pedals, gears, brakes, and other aspects of typical bikes, as their purpose is to enhance confidence, steering, and balance in young riders. If you are choosing a balance bike, your size options will be more limited, making it easier to find a good fit.

Little boy and his younger sister cycling outdoors

Picking a pedal bike is where sizing becomes tricky. You also need to choose a bike that meets a kid's riding needs, in addition to making sure you find a bike that's a great fit for them. What will they be using the bike for? Where will they be biking? Is this their first bike, or are they avid riders in need of an upgrade? All of these factors should be considered when deciding on which pedal bike to buy your child.

Types of Bikes for Big Kids

Choosing a well-sized bike is essential if you purchase it for a child, mainly because a bike that's an ill-fit can be dangerous. Aside from paying attention to size detail, you will also want to look into why a child will be riding. Kids that are not new to biking will often ride either a mountain bike or a hybrid bike. Neither is better than the other, but both types of bikes come with their own bells, whistles, and purposes.

Mountain Bikes

Generally, mountain bikes are used for tackling rough terrain. If you are buying a bike for a child who will be taking to the trails and going off roading for epic adventures, then you might want to consider looking at this style of bikes.

Hybrid-Style Bikes

Hybrid bikes are for riders who are sticking to sidewalks and paved paths. They are designed for comfort and efficiency, and are perfect choices for kids looking to spend their afternoons riding around the neighborhood.

Tips for Bike Sizing

After paying close attention to wheel size, your child's height, inseam, and several other factors, including which bike model works best per the kid's needs, shift your focus to tried and true tips from those who have shopped for bikes before you.

Adjust the Seat Height

How a child sits on a bike gives clues as to how well the bike fits a kid. A child should be able to sit on the bike and place the balls of their feet firmly on the ground. If only the tips of their toes touch the ground, and a youngster has to teeter from side to side to avoid tumbling over, the bike is too tall. If a child can place their feet on the ground and there is some bend in their knees, the bike isn't tall enough.

Pay Attention to Pedal Power

Pay particular attention to pedaling power, as this also gives away clues to how well the bike fits a child. Allow a child to test a bike out and watch where their knees land when they are pedaling. Do the knees come up to the handlebars? If so, the bike is too small for them. If it looks as though their legs barely bend no matter where they are in their pedaling process, then go down a size, because the bike is likely too large for their stature.

Be Aware of the Bar

Many bikes have a middle bar extending across them. Ask the child you are buying for to straddle this bar with their feet flat to the ground. There should be at least one to two inches of space between the bar and the child's body.

Grip the Handlebar

Lastly, look at the handlebar. How does the child hold it? A bike just the right size should allow the rider to gently bend their arms while steering. If arms look to be hyper-extended out forward, then the bike might be too big.

The Myth Behind Buying a Larger Bike to Grow Into

"We need a bike that will last for years, something they will grow into."

These are familiar words spoken by well-meaning adults who don't want to throw money away on a pricey bike that a kid will likely grow out of in the next year or two. Unfortunately, the "grow into" way of thinking isn't something that can be applied to kids and bikes. Purchasing a bike that is too large for a child can result in injury. You are better off buying a bike that fits their current size. When they outgrow it, sell it, hand it down to a younger or smaller child, or ask the bike store if they have a buy-back program for outgrown bikes.

Thankfully, bike manufacturers often take into account the fact that kids grow like weeds. Minor adjustments can be made to a bike to raise the seat or the handlebar. This helps to ensure proper fittings as kids have small growth spurts during their ownership of a bike.

Tools to Help You Choose the Perfect Fit

Use age, height, inseam, and wheel size to pick a bike that will be a great fit, or look to one of the nifty online tools geared to help bike buyers get their purchase right the first time.

Guardian Bikes Ridesizer - Buyers can enter a child's height and age into the tool, and a selected bike size will be generated for them.

woom Bikes Size Finder - Enter a child's age, height, and skill level, and the site will generate options to choose from.

The Beauty of Bike Riding

Bike riding is a timeless activity that millions of kids enjoy. Be sure to spend some time considering what a perfectly sized bike looks like for your little rider, so they are ready to roll when they receive their new wheels. Giving your kid an appropriately sized bike is a step in the right direction when it comes to safety. Additionally, teach children facts about bike safety, including always wearing a helmet while riding, and important road safety information like looking both ways and making eye contact with drivers before crossing a street. Then they'll be ready to let the good times roll!

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Kids Bike Sizes: A Parent's Guide to Finding the Perfect Fit