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Comparing Dirt Bike Sizes: Which Dirt Bike Is Right For You?

Chaparral Motorsports
March 11, 2015
Last Updated: April 15, 2021
Honda CRF125F
Honda CRF125F Dirt Bike

When it comes to picking the perfect dirt bike there several factors to consider such as your riding experience, height, and weight. Your riding experience will help determined whether you should get a bike with a bigger or smaller engine thus more or less powerful bike. Your height and weight will help determine the seat height. There are a variety of dirt bike sizes and and when determining which is best for you it's important to pay attention to the seat height and engine displacement of the dirt bike.

Adult sized dirt bikes will have taller seat heights ranging from about 35" to almost 38" with an engine displacement ranging from 230cc to 450cc. A kid size dirt bike will have a seat height that will range anywhere from 18" to 34" with engine displacement varying from 50cc to 150cc. While these numbers are general guidelines there is obviously room to cross over where you may be able to safely put an adult on a kid size dirt bike and vice versa. It comes down to your riding experience, height, and weight. When picking out a dirt bike your main goal is to be able to stay comfortable and secure on the bike. Going with a bike that is too tall or has too much power can be dangerous while going with a bike that is smaller or has less power can be great for those just learning but may be underpowered or too cramped and uncomfortable for taller or more experienced riders.

Your Experience Level

2013 Kawasaki KLX 140 Kid Riding Kawasaki Dirt Bike on Track
Kid Riding Kawasaki Dirt Bike on Track

Whether you're just getting your first dirt bike at 30 years old, or if you're planning on getting your child his or her first bike, experience is a critical factor to your decision. First off, if you're buying a bike for a new rider less than 5 feet tall and 10 years of age, you're going to want a dirt bike under the 110cc range. There are plenty of options that come with three-speed transmissions and automatic clutches to help a young first-timer get used to riding on two wheels before learning the clutch system.

However, if you're an adult and a first time rider, you want to get with something more appropriately sized, but likely keep the cc's under 250 to get used to the feel of a dirt bike. Additionally, if you're 15 or older, you want to get used to the clutch system if it's your first bike, but if you're already used to it, then size should be your next priority. Size plays an important role, but first you have to know your experience level before you purchase your first bike.

Dirt Bikes For Beginners

If you're just starting out on a dirt bike then it's always best to go with a smaller displacement motorcycle. Smaller displacement dirt bikes have less power and are much easier for beginners to handle. With less power these bikes aren't as intimidating and the power is more manageable for those who may be nervous or anxious about riding. For kids there are quite a few smaller engine displacement options with varying seat heights that can fit them. For adults on the other hand, you may find that you might have to jump on a bike that's not exactly the ideal size and may be a bit cramped but won't overpower or intimidate a new rider. A 125cc four stroke dirt bike can be a great bike for taller kids and smaller and lighter weight adults as the bike offers a decent seating position without having too much power.

Before you throw a leg over any dirt bike, no matter the size you should get in the habit of wearing the proper protective gear. Getting all the necessary dirt bike gear / motorcycle gear such as a helmet, dirt bike boots, gloves, pants, jersey and mx goggles, will help you stay protected and safe as you ride.

Your Height

When deciding on a new bike, your size truly matters to your overall safety and comfort on a dirt bike. You can get a general idea as to what size seat height will suit you best based on your overall height. However, before you purchase a dirt bike it's best to actually sit on the bike to see if it really does fit your stature as some people have shorter inseams or others have taller torsos or longer arms. The best ways to know if a dirt bike fits you is to get on the bike, sit forward and see if your feet touch the ground.

If you are flat footed on the ground while sitting up on the bike, the ride is likely too small for you. This will put more weight on the suspension, which you'll really feel when you hit a bump or a rock in the trail. However, if you're barely able to stand up straight on the bike and find yourself using the very tips of your toes to find balance, the bike is probably too large.

You want to be able to put one-third of your foot on the ground, so you're not flat footed or unbalanced on your tip-toes. If any big bump were to come your way, you want to be able to control the bike if you have to put your feet down.

Your Weight

For beginner riders who weigh less than 100 pounds versus a tenured rider who weighs 200 pounds, the amount of suspension you need will change dramatically. Beginner riders shouldn't start with a bike that is too small because their weight could affect the suspension, but people often learn how to ride much faster on smaller bikes instead of taller rides.

For those who weigh 150 pounds or less, it might be smart to work with something under 250cc to get accustomed to the bike's height and weight. However, for bigger riders, you want a ride that has enough suspension to take you down any dirt path comfortably. Choosing something between 250cc and 450cc might be a better choice. However, again, experience plays an important role - even if you're heavier or taller. Choosing a 450cc might be too powerful for the extremely novice rider, but going above 250cc's is smart for those who have grown accustomed to riding dirt bikes.

Dirt Bikes For Kids

If you're looking for a kid size dirt bike (we're talking kids under the age of 15) you want to pick something based on the kid's riding experience, height, and weight. There are quite a few kid size dirt bikes to choose from that range anywhere from 50cc to 150cc.

If you have a kid that is five or six years old and has never ridden a dirt bike then a 50cc dirt bike such as the Yamaha PW50 would be a good choice. The Yamaha has a low seat height of only 18.7" so it should fit the smallest of riders. The PW50 only weighs 90 pounds so it isn't overbearing or too heavy for most little ones. You can set the throttle to limit the amount of power the bike puts out which is very useful for brand new riders. As they gain more experience and confidence you can adjust the throttle to enable them to go faster. The PW is also has an automatic transmission so they don't have to worry about dealing with a clutch or shifting gears and they can strictly focus on throttle control, steering, and balance.

If you've been wondering what size dirt bike is best for a 13 year old, again the decision will be based on the kid's height and riding experience. Let's say for example the kid is of average height of about 5'1", and has no riding experience, then something like the Kawasaki KLX 140 may be a good option. This is a 4 stroke trail bike that is offered in three different heights ranging from 30.7" to 33.9" allowing them to choose which fits best. Taller/heavier riders should go for the tallest of the bunch, the KLX 140G, and shorter/lighter riders could opt for the KLX 140. Being an trail/offroad bike it is tuned and geared differently than a track oriented dirt bike to deliver smooth and predictable power--perfect for beginning riders.

On the other hand if you want to know the dirt bike size for a 14 year old that is a very experienced rider then you'll probably want something like a KX250. With a seat height of 37.3" the KX250 may be a bit tall for some 14 year olds but as experienced riders they will know how to properly handle the bike and over time most will grow into the bike in a few years. If the bike is just way too tall you could always make modifications to lower it so it's better suited for the rider. There is plenty of power from the KX250 to keep aggressive riders happy and racers competing at the top levels.

Dirt Bikes For Adults

Choosing an adult size dirt bike will consist of the same factors as choosing a kids size dirt bike: rider experience, height, and weight. An inexperienced adult who is on the shorter and lighter side could possibly find themselves sitting comfortably on a 125cc dirt bike such as a Honda CRF 125F. This is a trail bike with mild power and the Big Wheel version has a seat height of only 30.9" inches would should fit those with short legs. It's a light weight bike so it's easy to maneuver and pick up after a spill.

If you're over 6 foot 200-plus pounds, and a highly experienced rider then a 450cc dirt bike is the way to go for you. There are plenty of options in this rang,e it all depends on if you want a track oriented dirt bike or will be spending more time aggressively riding single track and trails. If you will be riding a lot of motocross tracks check out the YZ450F, the bike will suit your height and weight very well and there's plenty of power. For trail riders you could look at the Honda CRF 450X. It's based off the CRF 450R but has been tailored for the open world of high speed offroading with a wide-ratio six-speed transmission as well as other key components.

If you're riding experience is above beginner but not quite advanced and you're of average height and weight then a 250cc dirt bike would probably be ideal for you. Again there are plenty of options but if you just want a fun bike that isn't too powerful then something like the KLX 250 might be right up your alley. The KLX is a Dual Sport dirt bike that is completely street legal with a headlight, license plate holder, and blinkers. This means you can cruise down the road or city streets and then dip off onto a trail whenever you feel like it. With a 35" seat height and a curb weight of 305 pounds the KLX has a moderate seat height but is a bit heavier than a standard dirt bike, this isn't necessarily a bad thing as the heavier weight will make you more stable when cruising at speed around other vehicles on the highway.

The three adult size dirt bike examples we provided above are three different types of dirt bike intended for different types or riding/terrain and therefore differ in performance and components. The CRF 125 is a small and compact trial bike that is geared for easily chugging over tougher rugged terrain where low speeds might be the norm but can get moving at a decent pace when on flat sections. The YZ450 is a performance-oriented motocross track bike that is geared and tuned for quick acceleration and nimble handling. While it can be used on trails and offroading, the bike really excels in close quarters and dealing with obstacles where the rider has to repetitively jump, skim whoops, brake and accelerate quickly. As a dual sport dirt bike the KLX 250 is a middle of the road machine that can adequately tackle a variety of terrain, roads, and obstacles, giving you nearly limitless options for riding.

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