Does Your Kid Need a Bigger Bike?

Published on 05/13/2023 · 6 min readKids grow fast! That can make it hard to know when exactly it's time to get them a taller bike. Luckily, this guide will answer that question for you!
Sean Young, Cycling Expert
By Cycling Expert Sean Young

Photo by Kenny Eliason

If you’re anything like me, you’ll be asking this question long after they’ve graduated from high school, let alone grown out of that first balance bike. But if you’re observant, I invite you to continue reading as I share some ways to determine if your child’s current bike is an appropriate size for their height and ability. This article is also helpful to parents looking to get the first bike for their child, as the basic principles are the same.

How Children’s Bikes Are Measured

If your child’s current bike was given to you by an extended family member or neighbor, it’s important to know that, unlike adult bikes, kid’s bikes are measured by the size of the wheel and not the frame.

12” wheels are usually associated with balance bikes, meaning they have no pedals. Perfect for the youngest of riders, the seats are low so tots can put their feet down easily to find their balance as they scamper along.

If you’ve skipped this age to get your child riding, training wheels on a bigger bike accomplish the same results. If installing them on your kid’s bike at home, the goal is for new riders to learn balance, so don’t place the training wheels level to the ground with the rear wheel. The bike should teeter a bit.

Once you’ve read this article, if you come to learn the bike they are currently riding was too small for them from the start, don’t be surprised by a big jump in wheel size! The size progression for kids and their gear is not always linear. Kids grow fast!

If you’ve been handed a bike from someone else, it’s hard to say no to the generosity of others, not to mention the cost savings. A touch small on a loaner or a freebie is fine, but avoid bikes that are too big, even if you want them to grow into it.

A bike that is too big will be difficult for them to manage. Think of it like taking a large dog for a walk on a lease. Who is leading who? This is also a matter of safety in terms of when they need to quickly dismount from the bike or have an accident and fall; and they will fall. Kids can get caught up in the bike if it’s too big instead of having it fall away and free from their body.

Although wheel size is how children’s bikes are categorized, there are better ways to fit them to a bike. Read on for a few tips on how to find the best size bike for your kiddo.

Determining the Correct Size

Photo by Sean Young

When choosing which size bike to get your child, there are a few methods I’d like to review in the quest for a proper fit. Some key terms we’ll cover are standover height, saddle height, reach and inseam. Each one plays an important component in the fit puzzle for your child’s safety and enjoyment.

  • Standover height is the distance between the ground and the bike’s top tube.
  • Saddle height is how high the seat is from the ground.
  • Reach is how well a child can get a hold of the handlebars and work the brakes.
  • Inseam is the measured distance between the ground and your child’s groin.

Sizing Charts

Every brand has its own sizing chart, but you can use this one, with data provided by Schwinn as a general guideline.

Minimum 1-3 inch clearance between crotch of the intended rider and top tube of the bicycle frame, with both feet flat on the ground. Data provided by Schwinn

Standover Height

Let’s figure out if the standover height for your child’s bike is appropriate. Have your child stand over their bike, just in front of the saddle, by straddling the top tube. Depending on the comfort of your little ripper, there should be one to three inches between the top tube and their crotch.

If your child is a confident and experienced rider, it is alright if they are slightly on their tip-toes. If there are four inches or more between the top tube and your child’s groin, then it might be time to consider a bigger bike.

Saddle Height

Photo by Eduardo Soares

Now let’s check the saddle height on your child’s bike. When at the lowest part of the pedaling motion, the leg should have a slight bend in the knee, almost straight, but not quite. If the saddle is up almost to the highest point possible, then it might be time for a new bike.

Every seat post has a maximum height limit indicator etched onto it. The marking is often the same color as the post itself, so remove the seatpost and hold it at an angle to the light to find yours. This limit is for your child’s safety, so don’t set your child’s post above it.


In a safe place, have your child sit on the bike seat with their arms holding the handlebars. This can be done with a foot on the ground or not. Are they able to reach the handlebars and work the brake levers easily? If your child’s arms are bent at the elbows at over 45-degrees, it might be time to get a bigger bike.

Another thing to look at is the distance between their knees and the handlebars as they pedal. If there’s not much room, say, anything less than three to four inches, then it's probably time to size up.


Now that you’ve done some visual inspections, take a moment to measure your child’s inseam. Have your child stand against a wall or door in their bare or stocking feet. Place a hard-spined book between their legs up by their groin. Maintain the book firmly in place as your child moves forward, away from the wall. Measure the distance between the floor and the top of the book’s spine. That’s your child’s inseam.

This measurement is one of the best ways to see if a bike fits anybody really, child or adult! For newer riders, the safest and most confidence-inspiring saddle height is equal to their inseam. If your child’s inseam is 20 inches, a saddle height of 20 inches is just about perfect, for example. At this height, they can comfortably sit on the saddle with their feet flat on the ground.

For more experienced riders, this is adjustable to about one to three inches over their inseam. So for an inseam of 20 inches, the seat can be as high as 23 inches, or just at the point where the child is on tippy-toes while seated. If your child’s bike seat no longer reaches this height, then it’s probably time to purchase a bigger bike.

You may have noticed that I haven’t spent a lot of time on wheel size. The choice was intentional as the measurements mentioned above offer greater insight into whether your child’s bike fits than the wheel size alone. It’s entirely possible that your child needs a bigger bike but not a bigger wheel size.

Happy riding and don’t forget those helmets! Let your child pick out their own to encourage them to wear it. They are legally required in most places and need to fit them as well as the bike does!

To explore more Cycling articles as you pursue your journey in the sport, check out the Expert Journal here on Curated.

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