Mountain Bike Sizing Chart: What Size Do I Need

Mountain bikes are popular and liked by those who love mountain cycling. Currently, though, it’s a stylish pick amongst the youths who prefer to stand out amongst their peers. However, to enjoy riding a mountain bike, you need the right size, which will be comfortable, preventing you from back and leg strains.

Mountain Bike Sizing Chart

But what size of mountain bike should you pick? The ideal size can be a challenge to pick unless you look at a mountain bike sizing chart or consider your body structure and age. The sizing chart shows the right size depending on your height.

So, if you’ve intentions of buying any mountain bike, this guide is for you as we’ll discuss the best sizes to pick according to your age/gender or height.

What Size of Mountain Bike Do I Need?

Before buying any bike, you need to know that each has unique features that make it feel different when riding. This requires you to be keen on the sizing, depending on your age, gender, and height. Below are some of the right mountain bike sizes for you;

The wheel size Women Mountain Bike Sizing

Women’s Mountain Bike Sizing

Women’s bike sizing tends to be different from the others because they’ve unique body structures. You’ll find that a woman and man of similar age have varying weight, size, and body structure. So, you need to be keen to choose the right size that meets their height and is ideal for their body structure. To achieve this, look at;

  • The wheel size

Mountain bikes have varying wheel sizes, which are the wheel’s diameter. The wheel for women can be 26 inches, 27.5, or 29 inches. If you’re a petite woman, the best wheel size is 26 inches. But most women will be comfortable riding mountain bikes with wheel sizes 27.5 and 29 inches.

The wheel size -Mountain Bike Sizing Chart

  • The Frames Size

The frame of the women’s mountain bike you want to buy will determine how big or small the bike is. The women’s frame is measured in inches or generic sizes (small, medium, and large).

Note that the smaller the frame, the smaller the bike. Also, the women’s mountain bike has shorter lengths, narrow handlebars, and smaller frames. However, you can check the women’s size chart below to understand more.

The women Frames Size

Women’s mountain bike sizing chart

Height in inches and feet Height in cm Frame size in inches Frame sizes in cm
4’10’’-5’2’’ 148cm-158cm 13’’-14’’ 33-37
5’2’’-5’6’’ 158cm-168cm 15’’-16’’ 38-42
5’7’’-5’9’’ 168cm-178cm 17’’-18’’ 43-47
5’10’’-6’1’’ 178cm-185cm 19’’+ 48+


Kid’s Mountain Bike Sizing

Kids should learn to ride bikes as early as possible to make them pros. To enable your kids to enjoy riding mountain bikes, ensure you pick the right size that won’t make them struggle using them. A comfortable mountain bike for kids should enable your kid to sit and grip the handlebars easily. Your child should also pedal comfortably.

Kid's Mountain Bike Sizing

If you want to buy your kid a mountain bike, you need to look at their height bearing in mind how tall their legs are. This will help you determine the space between the top tube and the ground. If the distance is perfect, your child will straddle the bike while their feet are on the floor, preventing resting on the top tube and enabling them to be comfortable.

Additionally, your child should be able to grip the handlebars comfortably without stretching to reach them. Your child’s elbows should slightly bend when using the handlebars, which will help them steer and squeeze the handbrakes.

To know the right size of a kid’s mountain bike, you need to look at the wheel’s size. Kids’ mountain bikes wheels start from size 12″ to 24″. To help you understand the right mountain bike size for your kid, you’ve got to look at this sizing chart.

Kids Mountain Bike Sizing Chart

Wheel size Child’s height in inches Child’s height in cm Age Inseam length


12 inches 30’’-39’’ 90 2-4 12-17
14 inches 37’’-44’’ 90-105 3-5 16-20
16 inches 39’’-48’’   5-8 18-22
20 inches 42’’-52’’   6-10 21-25
24 inches 50’’-58’’   8-12 24-28
26 inches 56’’+   10+  


Even though most kids’ mountain bikes are made to have them ride upright, they should sit and see the direction without straining. Look for a bike size that will enable your kid to sit with the legs slightly bent under the pedal stroke.

Note that the estimated age doesn’t necessarily give your kids the ideal size for a mountain bike. This is because kids have different developmental milestones determining their height, legs, and torso sizes. For example, my 7-year-old child will not have the same legs and height as your 7-year-old kid.

Sizing Your MTB (Mountain Bike Sizing Chart)

Mountain bikes come in different sizes and shapes, requiring you to identify the right one that will make cycling enjoyable. However, choosing the right size at times becomes a problem, something that might make you settle for the wrong size. If you buy a smaller MTB, it means you’ve got to size up, but if it’s bigger, you need to size down to have the perfect pick.

Sizing Your MTB

Before making the final decision, it’s good to know that every manufacturer of mountain bikes has its way of sizing these bikes. Most of them categorize them into small, medium, and large sizes, with the main difference being frame sizes. The wheel’s diameter, suspension, and relative geometry number in all the bike brands remain the same.

As you plan to upgrade or size down, you’ve got to consider the frame’s size to get a perfect fit that will be comfortable to ride. You also need to look at the bike’s length vs. your height when doing this.

Sizing Down

When you buy an MTB and realize it’s bigger, it’s best to size it down to allow you to cycle comfortably. You should go for an MTB with a shorter wheelbase to achieve this. The bike should also be shorter than the previous one to allow you to ride in an upright posture.

Sizing Down

Go for an MTB with a stand-over height that you can adjust the seat position to reach the pedals. A shorter MTB is ideal for those with longer legs but lack flexibility. It’s also a good pick for anyone who likes riding while maintaining an upright posture.

In addition to that, consider the wheelbase. A shorter wheelbase will enable you to ride steadily and nimbly without getting tired. But don’t choose a low and longer cockpit which will require you to ride aggressively as you’ll be exhausted.

It’s advisable to size down if you like casual riding positions, less flexibility, and rides in a nimbly and whippy way.

Sizing Up

Consider sizing up when you have outgrown your MTB or bought a smaller one. Sizing up will increase the reach and wheelbase. You will fit easily into a bigger mountain bike with your long torso. Your flexibility will also improve when you size up, plus you’ll be riding while bending because of the increased reach.

Sizing Up

However, sizing up will allow you to ride in a more aggressive position which can be a great challenge, especially if you’re used to shorter bikes with short reach. When you choose to ride a mountain bike with a larger wheelbase (longer frame), ensure you’ve got a long, flexible torso that can withstand tough terrain. Remember, such bikes best suit mountain trails, a challenging ride on hilly or mountainous roads.

Important Geometry Measurements

Apart from getting the right MTB size, understanding the bike’s geometry is also crucial as it will improve your riding experience. Remember, the bike’s geometry largely determines the bike’s design. We’ll help you understand the important geometry that defines the shape, how you handle the bike and affects the ride below;


Reach is the horizontal distance between the mountain bike’s bottom bracket and the headtube. The bike’s reach is how long its frame is. It indicates what the bike will look like and how spacious it will be for you while riding.

Bigger MTB has a longer/bigger reach, enabling you to ride aggressively and increase flexibility. It’s a good pick for those who love tough terrains and are ready for the challenge. However, a bike with a smaller reach means the head tube is longer, making steering more direct. It also makes your hands extend beyond the front axle, allowing you to feel more secure while cycling on hilly roads.

You can extend the bike’s reach. The wheelbase will also increase if you do this, requiring a longer torso. Plus, you’ve got to be flexible. You can measure your bike’s reach with a tape measure and a plumb bob.


Your bike’s stack is a reflection of how the handlebars will be. It’s the vertical distance from the center of the bottom of the bracket to the head tube. If you’ve got an endurance MTB, its stack will be longer than a racer bike.

The stack measurements are important for shorter people who want MTB with a bigger wheel size. It’s also suitable for anyone who likes cycling long distances without a taller handlebar. If you’re shorter, it’s advisable to go for an MTB with a lower stack height. However, most taller people don’t have a problem with the stack height unless they intend to go low.

Head Tube Angle

The head tube angle is the measurement between the ground and the front frame. It shows you how to steer the bike. A steeper head tube angle of about 70 degrees will make your motorcycle drive at great precision and lower speed. Note that the head angle determines the distance of the front axle on your hands.

Head Tube Angle Mountain Bike Sizing Chart

Head Tube Angle – Mountain Bike Sizing Chart

If you’re riding on flatter ground, the steering response will be more responsive, and it can be hard to manage the bike. Your bike will wander more, unlike when going uphill, and you’ve got to put in a lot of effort to stabilize. But after the bike’s speed increases as you go downhill, the slack head angle will help it be more stable.

Chainstay Length

Chainstay length is the distance from the bottom bracket to the rear wheel axle. It affects how you handle the bike and varies from brand to brand. A shorter chainstay length reduces the wheelbase and makes it easier to move the bike.

Chainstay Length Mountain Bike Sizing Chart

Most people prefer shorter chainstays as they enhance riding fun and increase stability when going uphill. A short chainstay ranges between 420-435mm and allows you to wheel and flick around on the road. However, a longstay of between 440 and 455mm prevents the front end from lifting while climbing a steep road.


This is the space between the front axle and the rear. It’s made up of chainstay length, head tube angle, and reach. A longer wheelbase means the bike’s frame is bigger and determines how you’ll handle it.

If your bike has a longer wheelbase, it will be more stable when riding at high speed on a hilly trail. But it requires you to move at a slower speed on a tough track. On the other hand, a shorter wheelbase is easy to steer on tight trails at a slower speed.

Wheelbase Mountain Bike Sizing Chart

Wheelbase- Mountain Bike Sizing Chart

If you’re an aggressive flexible rider, it’s best to go for a longer wheelbase when moving up the trail. It’s advisable to look if there’s an added wheelbase length and what can cause this. A longer chainstay or a slack head angle may affect the wheelbase length.

Bottom Bracket Height

The bottom bracket height is the measurement between the ground and crank spindle. It gets affected by the wheel’s size. For example, a bigger wheel size will lift the bottom bracket higher. The bottom bracket also determines how you’ll handle the bike. A lower bottom bracket increases the bike’s stability and helps you balance better. It also improves the cornering ability of your mountain bike.

Bottom Bracket Height Mountain Bike Sizing Chart

Bottom Bracket Height Mountain Bike Sizing Chart.

Additionally, a long mountain bike will have a higher bottom bracket to make in for the extra suspension sag when you sit. It’s best when pedaling on the uneven trail without bashing the pedals.

Factors That Affect MTB Sizing


Before buying any mountain bike, you’ve got to consider your arms sizes. Having the right bike size will enable you to hold it comfortably, preventing your shoulders and arms from being unrelaxed. Your elbows should bend slightly when using the right bike size.


Knees are important in coordinating the bike’s movements. You should have flexible knees that can bend slightly at the bottom of every pedal’s stroke. The flexibility of your knees will determine your speed and the control of the pedals.


If you plan to buy a mountain bike, ensure you look at the saddle. A good saddle position will help you maintain your posture and balance while cycling. You will also control and pedal better without straining when the saddle fits you well. Remember, a higher saddle will make you overstretch your legs to reach the pedal if you’re shorter.


The bike’s frame largely determines the size of the mountain bike. When buying a bike, ensure you look at its size versus your height to allow you to ride without straining. It’s advisable to go for a shorter frame if you’re short to enjoy using this bike. If you like aggressive riding and are flexible, a long frame will do you good.


If you want to have the best MTB, check on the shifters. Try using the bike with different shifter settings to see how it works. You can tilt to see how easy it is to control the bike while in that setting.

What Happens When You Get the Wrong Size?

When shopping for an MTB, it’s best to pick the right size to enjoy using it and achieve your set goals. If you buy the wrong size, it will lead to complications like;

Back Pains

There’s nothing unbearable like having back pains. When you’re using the wrong MTB size, your back will bend excessively as you try to fit on the bike. The wrong posture will make your back muscles not support the rest of the body and eventually lead to pain. However, you can avoid this problem by adjusting the handlebars or the reach from the bike’s saddle to the bars.

Knees Problems

If you try fitting in the wrong MTB size, you’ll experience pain in your knees. When the bike is lower or higher, the distance between the saddle and pedals will be short or long. You will strain to reach the pedals. You will also be forced to use your shoe cleat to reach the pedals, making it sit in the wrong position. This will make you have knee pains which can worsen if you continue using the wrong bike size.

Strained Hips

Your hips will strain when the bike’s saddle is too high or too low if it’s smaller. When the saddle is higher as you ride, you’ll encounter hip problems as you’ll put more power to reach a low-lying pedal. Bending your legs while cycling will also give you problems in the hips area. So, it’s best to go for the right size MTB to enjoy using it.

Arms And Shoulders Stiffness

When you ride a smaller or bigger bike, your shoulders and arms will overstretch or bend as you reach the handlebars. When this happens, the muscles around these areas will be painful and stiff from too much stress. After testing the saddle to-bar-reach, you can know if the bike is not the right size.

But you can improvise the bar by introducing upsweep or backsweep. If these parts continue hurting, it’s best to upsize or downsize.

Bottom Line about  Mountain Bike Sizing Chart

Mountain bikes come in different sizes, fitting certain ages depending on their height and body structure. Before buying any mountain bike, look at the features of each cycle vs. your body structure to help you settle for the right size. You can use a sizing chart to guide you through or try using the bike before bringing it home. Don’t forget to look at the geometry measurements to avoid experiencing problems from choosing the wrong bike size.

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Mountain Bike Sizing Chart: What Size Do I Need

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