What Size Dirt Bike Do I Need?

What’s the average size dirt bike? What size dirt bike is right for me or my kid? If these are the questions you need answered, then this is the most important article you’ll read about it! 

KTM 200XCW is a little big for my size
My 200XCW is a great bike but it’s a little tall for my liking.

If you’re looking for the perfect beginner dirt bike, figuring out what size fits you is critical when you first start riding, but it’s not the only thing you should be considering. In this dirt bike size buying guide, we’ll look at the general appropriate size dirt bikes for each age and height group. You will also learn what other important factors there are to consider when buying a new dirt bike.

What Size Dirt Bike Should I Get?

The size of a dirt bike is determined in two different ways. The physical size of a dirt bike itself, which is the seat height, is a very important factor in determining which dirt bikes will fit you. 

The engine size is the other way to measure the size of a dirt bike. The engine size is referred to as “CC”. A motorcycle or dirt bike CC is the engine displacement size calculated in “Cubic Centimeters”. This is similar to how car engines have been categorized in the past, such as a Chevy 350ci V8 engine. The 350ci stands for “350 Cubic Inches” of engine size/displacement. While it’s not the rule, generally the larger the number the more power a dirt bike will have. A 450cc dirt bike has a larger engine than a 125cc dirt bike, and it also has a lot more power. 

CRF230F cylinder showing the "CC" size
The Displacement size of the engine is usually stamped on the side. 223cm is the “CC”

There’s More To Consider Than Just “Size”

It’s true that you shouldn’t buy a dirt bike that is too big for you, but the seat height and engine size aren’t the only specs you need to look at. 

If you are an adult or teen that is new to dirt biking, you need to look at the article on the best beginner dirt bikes guide. It goes every little detail that will help you determine what the best dirt bike to start on is for you.

Here are the top factors you need to consider in addition to size to find which dirt bike is right for you:

  • Seat height
  • Engine size
  • Type of engine (built for trail riding or racing)
  • Electric or kick-start
  • Reliability
  • Price

What Is A Kid Size Dirt Bike?

There is a large selection of dirt bikes for kids. Gas powered and electric bikes are made for little kids as young as 3 and 4 years old, and up to 12 years old. So, which size is best for your kid? First, let’s look at what sizes are best for each age group, and then cover a chart for the sizes of all the best kids dirt bikes. 

kids dirt bike sizing xr50 xr70 and xr200
Honda Dirt Bikes For Kids

Dirt Bike Size For Kids Age 3, 4 and 5 Years Old

Are you always on the lookout for a bargain? I like buying things for cheap, but I don’t like buying cheap things. For that reason, I don’t want to advertise cheap Chinese or other foreign made dirt bikes that have very low performance and even lower quality.

Isn’t it so frustrating when you buy an expensive product and it proceeds to fall apart after using it once or twice? I can totally relate, and that’s why I won’t promote any kind of product that has little to no ability to perform. Sorry, my rant is over now…

A dirt bike that your little child starts on needs to be small enough for them to handle, but also function properly and reliably. Below is a simple chart that you can use as a guideline for what the size (seat height) of a dirt bike should be for a certain age boy or girl to ride, as well as adults of all sizes.

Dirt Bike Size Chart (Seat Height):

Age/HeightSeat Height
3-6 years old18-21 inch (45-53cm)
6-8 years old21-24 inch (53-61cm)
9-10 years old24-27 inch (61-68.5cm)
4’10”-5’0″ (147-152cm)27-30 inch (68.5-76cm)
5’0″-5’2″ (152-157.5cm)29-31 inch (73.5-79cm)
5’2″-5’4″ (157.5-162.5cm)30-33 inch (76-84cm)
5’4″-5’6″ (162.5-168cm)33-35 inch (84-89cm)
5’6″-5’8″ (168-173cm)34-36 inch (86-91.5cm)
5’8″-5’11” (173-180cm)35-38 inch (89-96.5cm)
6’0″+ (183+cm)37+ inch (94+cm)
Dirt Bike Seat Height Size Chart

The Outlier

The only problem with just looking at seat height in relation to rider height is the inseam length. Inseam length is from the crotch to your foot. This chart is based off of an average length inseam for a given height. 

If you have a longer than average inseam (long legs in proportion to your upper body length) then you would probably fit better on a taller bike than what is recommended on the chart. 

What Is A Medium Size Dirt Bike For Teens & Small Adults?

A medium sized dirt bike is a bike that has larger wheels and a taller seat height than a kids dirt bike, but doesn’t have full sized wheels or the tall seat height that a full size dirt bike has.

However, some full-size dirt bikes may be considered medium in size because the seat height is so low. Dirt bikes with a low seat height but still have full size wheels are great for shorter than average riders.

ttr125l medium sized dirt bike
TTR125L is a great medium sized dirt bike for kids and small adults.

Medium Size Wheels

Most medium size dirt bikes have a 17/14 inch or 19/16 inch wheel and tire size. Except for extreme cases, the front wheel is always larger in diameter than the rear wheel.

So, most medium sized dirt bikes have a 17 inch front wheel with a 14 inch rear wheel combination, or a 19 inch front wheel with a 16 inch rear wheel.

Having larger wheels increases the ability to ride over obstacles with less work. The downside is that with bigger wheels, the seat height is usually higher.

Medium Size Seat Height

A seat height between 30 inches (76cm) and 35 inches (89cm) is considered a medium size for dirt bikes. 

Popular Medium Size Dirt Bikes and Their Seat Height

  • TTR125 – 30.5” (77.5cm)
  • KLX140L – 31.5″ (80cm)
  • CRF150F – 32.6″ (83cm)
  • KLX140G – 33.9″ (86cm)
  • CRF230F – 34.6″ (88cm)

Smaller men and adult women can still ride a full size dirt bike, but it will require more balance skill. However, there are ways to lower the seat height of a dirt bike.

What Is A Full Size Dirt Bike For Adults & Big Riders?

Full size dirt bikes have wheels that are 21 inch in the front and 18 inch in the rear (motocross bikes have 19 inch rear wheels). Some “full size” dirt bikes may be considered a “medium size” dirt bike because the seat height is lower, even though they have the 21/18” wheel sizes. The seat height is above 35 inches (89cm). 

Popular Full Size Dirt Bikes and Their Seat Height:

  • Yamaha YZ125 – 39.3″ (100cm)
  • KTM 150XCW – 37.8″ (96cm)
  • Kawasaki KX250F – 37.0″ (94cm)
  • Honda CR250R – 37.8″ (96cm)
  • Husqvarna FC 350 – 37.4″ (95cm)
  • Yamaha YZ450F – 38.0″ (96.5cm)

Dirt Bike Engine Size

There are so many different engine sizes, so how do I know which one is best for me? If you’re new to riding, it’s best to start on a dirt bike that has a less powerful engine. 

You can follow the chart below for recommended dirt bike engine size, but this is just a general guideline.

  • 3-6 year old: 50cc
  • 6-8 year old: 50-80cc
  • 8-10 year old: 80-110cc
  • 10-12 year old: 110-150cc
  • 12-14 year old: 125-200cc
  • 15-18 year old: 125-250cc

What Is The Recommended Dirt Bike Size For Me Then?

Every rider is different in what will fit best. If you have zero experience, choose the bike that has a seat height that fits your actual height, and has an engine with moderately low power. The goal is to start on the easiest bike to ride, so choosing one with smooth power that you can handle is very important. This will usually narrow it down to an air-cooled 4-stroke trail bike.

honda crf230f air cooled 4 stroke trail bike
Awesome trail ride in the Montana on my air-cooled 4-stroke trail bike.

Dirt Bike Seat Heights From Shortest To Tallest:

Dirt BikeEngine SizeSeat HeightType of dirt bike
Yamaha PW5049cc18.7″Trail
Honda CRF50F49cc21.6″Trail
Kawasaki KLX110112cc26.8″Trail
Honda CRF110F109cc25.9″Trail
KTM 65 SX65cc29.5″MX
Yamaha TTR125124cc30.5″Trail
Honda CRF125FB125cc30.9″Trail
Kawasaki KLX140L144cc31.5″Trail
Honda CRF150F149cc32.5″Trail
Yamaha YZ8585cc33.1″MX
Kawasaki KLX140G144cc33.9″Trail
Honda CRF230F223cc34.6″Trail
Beta XTrainer293cc35.8″Enduro
Beta 200RR190cc36.6″Enduro
Honda CRF250X249cc37.7″Enduro
KTM 125SX125cc37.8″MX
Kawasaki KX250F249cc37.2″MX
Suzuki RMZ250249cc37.6″MX
Husqvarna TX300293cc37.4″Enduro
Yamaha YZ250FX249cc38.2″Enduro
Dirt Bike Sizes from shortest to tallest seat height

Choose The Type Of Dirt Bike First

As you can see, the seat height doesn’t always correlate to how big the engine size is. First, you need to narrow down what type of dirt bike you want to ride. This could be a motocross bike, trail bike, enduro bike, or perhaps another kind of off-road bike. 

Then A Seat Height Range

Once you decide on what kind of dirt bike you want, pick from the range of seat height that best suits your height. It doesn’t have to be perfect, but it should be within 2 inches (5cm). Just remember that the lower the seat height, the easier it will be to ride. This is especially true if this will be your first dirt bike.

Now Choose The Best Dirt Bike To Fit Your Needs

After choosing the type of dirt bike and the approximate size bike you will need, take a look at the specs and what each of the models have to offer. Are they easy to start? Are they reliable? Is the power smooth or abrupt? Will the suspension work for the kind of riding you’ll be doing? How much does it cost? These are all important factors that you will have to figure out before choosing a good dirt bike for you. 

With that said, it’s better to just pick one than to spend weeks or months trying to decide which is the “Perfect Dirt Bike” for you.

To save you time, I’ve already narrowed down the best beginner dirt bikes for teens and adults here.

Kelley Fager

Kelley started riding a Honda 50 at the age of 6 years old. The passion for dirt bikes started there and grown into a lifelong pastime of riding and learning how they work. Motocross Hideout is the result of sharing his past, present, and future knowledge and experience.

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