20 Inch Bike For What Size Person? Answers Here.

Everybody has a perfect beginner bike. But if you want an ideal bike for kids, a 20-inch bike may be what you seek. If you want to be sure that a 20-inch bike is best for you, continue reading. We will cover everything you need to know about who can ride a 20-inch bike, how to size a bike and tips on picking the ideal bicycle for your new rider.

20 Inch Bike For What Size Person

The main thing that determines who can ride a 20-inch bike is height. A 20-inch bike is best for shorter riders, usually kids. Most kids are ready for 20-inch bikes when they are approximately 6 years old.  If you think your child can handle their first bicycle without training wheels, please continue reading to learn how to size a bike properly.

How to Size a Bike

There are two basic ways to size a bike: height and inseam. If you track your child’s growth, you probably already know their height! But what is an inseam, and why does it matter for sizing a bike?

The inseam is, put bluntly, the distance between your crotch and the ground. To find the length of your inseam, stand with your bare feet 6–8” apart and have an assistant measure with a yardstick or measuring tape. If this makes you uncomfortable, have a professional at a bike store do it instead. However, doing this before you even go to the bike shop or order online will save a lot of trouble!

This chart details how to find your ideal wheel size based on height and inseam:

HeightInseam LengthWheel Size
3’1” – 3’7”16–20”14”
3’7” – 4’0”18–22”16”
3’9” – 4’3”20–24”18”
4’0” – 4’5”22–25”20”
4’5” – 4’9”24–28”24”

The usual advice is that if someone is between sizes, it is wise to move a size up. However, many kids enjoy riding around quickly, so you must balance size, budget, and frame weight to find the best bike. If you have older kids, you must also remember that kids’ bikes are measured using wheel size, and adult bikes use frame size for their measurements.

Is Measuring That Important?

The answer is: absolutely! Kids grow at different rates, so age estimates aren’t the best ways to guess if a bike will be good for someone or not. But there are many reasons to make sure you get the right size of bike, especially for a new rider. These include:


Safety is the most important reason to get the right size of bike. A rider’s feet need to be able to reach the pedals comfortably. If the stretch is too long, the person will be straining; if it’s too short, their knees may knock into the handlebars, which could cause several problems. Even a helmet can’t protect someone from a bike that’s too small or large for them!


As you may have guessed, having a bike of the wrong size isn’t just unsafe but also uncomfortable. Along with pedalling being unsafe and either cramped or strained as described above, getting the wrong size of bike can also lead to back pain after some time.


Without getting too deep into it, the ability to pedal without pain is also the ability to pedal efficiently. The more you strain to pedal, the more tired you will get, and the less you will enjoy riding. Even though the concept of “efficiency” may be lost on a young rider, the notion of “trust me, you’ll enjoy riding more” probably will not!

As your child grows, it may be wise to adjust the saddle height before investing in a new bicycle. But if your child’s knees are banging against the handlebars no matter what you do, it is time for a bigger bike.

Types of 20-Inch Bikes

Generally speaking, there are two kinds of 20-inch bikes on the market: general bikes and mountain bikes. Depending on the requirements of the rider and the area, one bike type may be preferred over another.

“Cruiser” Bikes

Roughly comparable to a “city” bike, most of the 20-inch bikes on the market are basic, one-speed bikes called “cruisers.” They don’t do any one thing particularly well but are excellent for riding around the block. These are fine for a first bike, but if your child eventually wants something faster, or something that can handle rough terrain, the need for a new bike will probably come sooner rather than later.

Mountain Bikes

A 20-inch bike can also be someone’s first mountain bike. These bikes have heavier frames and knobbier tires. If you know your child wants to ride on mountain trails and doesn’t care about racing their friends, this may be the best 20-inch bike for them.

Other Considerations

We realize that many people reading about 20-inch bikes are probably parents buying a child their first “real” bike. For this reason, we have a list of other considerations that didn’t go anywhere else.

Used VS New

It is tempting to buy a bike at a “big box” store, especially if your kid sees a design that they adore. But don’t open your wallet just yet. There are many reasons that your first 20-inch bike should not be bought on the spot.

We mentioned that kids generally prefer lighter bikes. Most of the time, bikes found at “big box” stores are made with low-quality, heavy materials. The average that you should be paying is $200-225. Anything under that should ring alarm bells.

Buying a used bike is another option. Unlike with an appliance, it is fine to buy a used bike that someone has outgrown. If you live in a neighbourhood with many other kids, and one of them has a bike that they can no longer ride, ask politely if you can buy it at a discount. Be sure to ask if the previous rider had any problems with it, just in case. They might even give it to you for free!

Tire Types

Picking the right type of tires for any bike depends on what you will be using the bike for. If the bike is mostly going to be a “sidewalk” bike, it will not need the traction that knobby tires would provide. In addition, if you want to go fast on relatively clean pavement, smoother, narrower tires are better. The same rules apply to adult bikes as well! If the bike will be on slick pavement, you will need to consider a different tire type versus if the bike will be on dirt roads.

Brake Types

Finally, it is important to consider what kind of brakes the bike has. Many children’s bikes made in the U.S. have “coaster” brakes, sometimes called “back-pedal” brakes because you stop the bike by pedalling backwards. These are being phased out in favour of handbrakes. Handbrakes are lighter, safer, and generally seen as superior to coaster brakes. There are still reasons to use coaster brakes, but for more experienced riders, hand brakes are usually preferred.

Final Thoughts

More often than not, a 20-inch bike is best for kids that have just taken off their training wheels and are ready for a more serious bike. Still, it is wise to do all the measurements you need at home, then ask a professional for advice on your kid’s perfect bike. By reading this guide, you have already armed yourself against a poor purchase, and are more likely to buy a bike your child will truly enjoy.

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