Dirt bike size guide: Calculate the correct dirt bike height and engine size

Choosing the right size dirt bike is super important. If you get it wrong you'll have bike that's either stupidly tall and overpowered, or one that lacks power and bottoms the suspension over every bump. In this post you'll learn how to choose the right engine size, and the correct seat height, to match you and your current level of experience.

What size dirt bike engine do you need

The first thing to think about is the engine size that you need. This will depend on your age, experience, and your weight. We'll start look at age, but don't be confused by thinking that the older you get, the bigger engine you need, as this isn't always the case.

For example: an experienced 15 year old may be able to rip around a motocross track on a 450 cc race bike with no problems. But an inexperienced 30 year old may struggle to ride around the same track with a much smaller 125 cc dirt bike.

Seat heights will vary, as will the height of the rider, so we'll find out how to find the correct seat height later.

Experience level

Your level of experience should always be taken into account, as a dirt bike that's too powerful can be dangerous, and it will slow down the learning process. For kids or any age that are complete beginners, a twist and go throttle will always make things easier to begin with.

After mastering the twist and go dirt bikes, a semi automatic with a simple 3 speed step through gearbox like the Honda CRF50F is preferred.

Adults and kids over the age of twelve can jump straight onto a six speed manual dirt bike. But always start small and work your way up, big powerful race bikes can be way too much for complete beginners to handle.

3-6 years old

Kids getting their first dirt bike will be looking at a 50 cc engine with a twist and go throttle. This lets them learn balance, and the sensation of riding under power, without having to worry about a clutch and gears.

6-8 years old

Between the ages of 6 and 8, kids that have ridden twist and go dirt bikes will do great on a 50 cc semi-automatic dirt bike, so they can get to grips with shifting. If they have not yet ridden, a taller twist and go design will also suit these young riders perfectly.

8-11 years old

Between 8 and 11 years old, kids will be able to use a standard gear box, so a 65 cc mini dirt bike will be the best choice. These bikes have all of the same controls as a full sized adult dirt bike. If your kid hasn't yet ridden a dirt bike, it may be best to start them on a 50 cc twist and go design before trying to figure out a clutched machine.

11-14 years old

At this age it gets more tricky, as rider height and weight will vary massively. Suitable engines could range from 110-150 cc 4-strokes, or 80-100 cc 2-strokes. Those with previous riding experience can move up to the bigger engines. We'll list lots of suitable dirt bikes later.

15-17 years old

Again rider height and weight will vary considerably. Some riders will be stepping up on to adult sized bikes, but some will need a smaller bike. Good beginner choices will be 125-150 cc 4-strokes, or 100-125 cc 2-strokes.

Adults

If you've never ridden a dirt bike it's recommended that you don't start on a race bike, but go for a 4-stroke fun bike. You have a ton of options ranging from 125-250 cc 4-stroke engines, all listed below.

If you can already ride, and you have at least a year of riding experience, a 250 cc 4-stroke or a 125 cc 2-stroke race bike will be fine. Don't jump straight onto a 450 cc race bike, as these dirt bikes are a lot to handle.

What seat height do you need

Finding a dirt bike with the correct seat height will ensure you don't loose balance and drop the bike when starting and stopping. It's also a good way of making sure the suspension is suitable, and won't bottom out while riding.

Looking at the seat height quoted in the manufacturers specifications is a great place to start, and it will give you a good idea of the dirt bikes suited to you. All dirt bikes are different, so don't expect every 125cc dirt bike to be the same height as the last one you looked at.

If you're buying a brand new bike, you'll be able to visit the dealership and sit on a few bikes to find the right size. But if you're buying a used bike, it's best to match yourself to all suitable bikes before going to view one. This way you won't have a wasted journey simply because the bike was too tall or too small for you.

To get a good idea of what seat height you'll need in a dirt bike, take the measurement from the floor, up to the highest point of your crotch. Do this standing with flat feet. You know what size engine you need, so when you have your measurement, you can find a suitable dirt bike on the list below.

When you have a bike in mind, scroll below the list to see how to test the height when you're sat on the bike.

Popular dirt bike options and seat heights

3-14 years

• Yamaha PW 50 (Twist and go with a seat height of 18.7 inches)
• Yamaha TTR50E (seat height 21.9 inches)
• Honda CRF50F (seat height 21.5 inches)
• Suzuki DR-Z50 (seat height 22 inches)
• KTM 50 SX (seat height 26.8 inches)
• Husqvarna TC 50 (seat height 26.9 inches)
• Yamaha TTR110E (seat height 26.4 inches)
• Yamaha YZ 65 (seat height 29.5 inches)
• Suzuki RM 65 (seat height 29.9 inches)
• Kawasaki KX 65 (seat height 29.9 inches)
• KTM 65 SX (seat height 29.5 inches)
• Husqvarna TC 65 (seat height 29.5)
• Kawasaki KLX 110 (seat height low version 26.8 inches. Tall version 28.7 inches)
• KTM 85 SX Big or small wheel (seat height Big wheel: 35 inches. Small wheel: 34 inches)
• Kawasaki KX 85 (seat height 32.7 inches)
• Yamaha YZ 85 (seat height 33.1 inches)
• Suzuki RM 85 (seat height 33.5 inches)
• Husqvarna TC 85 big or small wheel (seat height Big wheel: 34.4 inches. Small wheel: 33.4 inches)
• Kawasaki KX 100 (seat height 34.3 inches)
• Yamaha TTR125LE (seat height 31.7 inches)
• Honda CRF125F (seat height 30.9 inches)
• Kawasaki KLX 140 (low version: seat height 30.7 inches. high version: 31.5 inches)

Over 14 years and Adult bikes

• Kawasaki KLX 250 (Enduro bike. Seat height 35 inches)
• Kawasaki KX 250 (seat height 37.2 inches)
• Kawasaki KX 450 (seat height 37.6 inches)
• Yamaha YZ 125 (Seat height 38.4 inches)
• Yamaha YZ 250 (Seat height 39.1 inches)
• Yamaha YZ 250F (Seat height 38.2 inches)
• Yamaha YZ 450F (Seat height 38.6 inches)
• Yamaha TT-R230 (Seat height 34.3 inches)
• Honda CRF 250 XLR (Seat height 37.7 inches)
• Honda CRF 250 RX (Seat height 37.8 inches)
• Honda CRF 450 RX (Seat height 37.7 inches)
• Honda CRF 250 R (Seat height 37.6 inches)
• Honda CRF 450 R (Seat height 37.8 inches)
• Husqvarna TC 125 (seat height 37.4 inches)
• Husqvarna TC 250 (seat height 37.4 inches)
• Husqvarna FC 250 (seat height 37.4 inches)
• Husqvarna FC 350 (seat height 37.4 inches)
• Husqvarna FC 450 (seat height 37.4 inches)
• Suzuki RM-Z250 (Seat height 37.6 inches)
• Suzuki RM-Z450 (Seat height 37.8 inches)
• Suzuki DR-Z125L (Seat height 32 inches)
• Suzuki RMX450Z (Seat height 37.4 inches)
• KTM 125 SX (Seat height 37.4 inches)
• KTM 150 SX (Seat height 37.4 inches)
• KTM 250 SX (Seat height 37.4 inches)
• KTM 250 SX-F (Seat height 37.4 inches)
• KTM 350 SX-F (Seat height 37.4 inches)
• KTM 450 SX-F (Seat height 37.4 inches)

Sitting on the dirt bike to check the size

Just because the leg measurement looked right, it doesn't always mean that the bike will be a suitable size for you. Your weight will make a difference, so this part is important.

Sit on the seat in the riding position, and keep the dirt bike dead upright. Place all of your body weight onto the dirt bike, making sure no weight is taken by your legs.

To check the bike is the right size, you should be touching the ground with both feet. If your feet are flat, the bike is too low; if you can only touch the ground with one foot, the bike is too high. You should be touching the ground with both feet in the tip toe position.

This is the best way to find the correct size dirt bike, but bare in mind that when the suspension is adjusted (stiffened or softened), the height can slightly increase or decrease. This will only be a very small amount, but if you're already on the upper limit, it may cause problems.

Other things to consider for dirt bike sizing

Big or small wheel

If you look at the list of bikes for kids, you'll notice that some will say big or small wheel. There are also some, like the Kawasaki KLX, that have tall or small versions, this is also achieved by changing the wheel size.

These differences are only small, but they're enough to make a difference for kids that are lighter, but need a bigger bike. Instead of being held back by their weight, kids can continue to progress on a larger bike, or move up to a higher race class.

Tall riders

Tall riders may sit flat footed, even on the tallest of dirt bikes. Unfortunately there isn't much you can do for this besides buying a thicker seat foam to boost the seat height slightly. But one thing you may wish to do, is raise the height of the handlebars.

Handlebar height can easily be increased by changing the handlebars for a higher set as explained HERE. Or by changing the handlebar clamps, or both. This will straighten your back while riding, and bringing your arms up will likely improve the handling as it moves your weight backwards.

Thanks for checking out the dirt bike size guide! When you have found the correct dirt bike size, find a way of easily transporting the bike by clicking HERE.

Check out some awesome helmets HERE.

Or learn some fun facts about dirt bikes HERE.