Mountain Bike Sizing Frame Guide For Beginners

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When choosing the best mountain bike, the size of the frame is one of the most important considerations. It will dictate how the bike fits the rider. When the bike is suitable for your height and body type, it will be easier to control, and you will be more comfortable. Otherwise, you will compromise your performance on the trail. 

If you know nothing about mountain bike sizing, we are here to extend a helping hand. Read on and we’ll help you pick the right frame size that will work best for your needs. 

The Importance of the Right Mountain Bike Sizing 

Among others, the right mountain bike frame size is important because it keeps you comfortable on your ride. It will help promote the proper riding position. This means that it will be easy for your feet to reach the mountain bike pedals and for your hands to hold the MTB handlebars

With a properly fitting mountain bike, you can prevent fatigue, back pain, wrist pain, and leg pain, among others. Regardless of how challenging the terrain is, your body will not experience too much strain. 

Aside from comfort, the right size is also important for control. If the bike is too big or too small, it might be more difficult to maneuver. You will have a hard time steering it to the direction where you would like to head. Plus, the right size will also make the bike more stable. 

How Do You Size a Mountain Bike? 

To size a mountain bike, consider your height and match it to the sizing chart of the manufacturer. Mountain bikes are sized as small, medium, or large. They are also sized in inches or centimeters. The sizing is based on the frame, which is the measurement from the top of the seat tube to the center of the bottom bracket. 

For a better understanding of the mountain bike frame size, below are some of the most important things that will have an impact on the final size. 

Reach 

The reach of a mountain bike refers to the horizontal distance between the center of the headtube and bottom bracket. It is the most important measurement as it will be indicative of how you can reach the pedals. It will dictate how you stand on your bike, which is especially important when you are descending. With the right reach, it will be easier to draw power from your hips and remain stable when you are standing up. 

If the reach of the bike is too long, you might end up leaning and stretching too much. On the other hand, when it is too short, your weight will quickly shift, and you will end up being inefficient as you pedal. 

Stack

As you understand the geometry of the mountain bike, the stack is another important measurement to consider. This is the vertical height from the center of the head tube to the bottom bracket. It dictates the minimum bar height and will also measure your seated position when you are pedaling. While this is a critical consideration, reach is more important when sizing a mountain bike. 

Head Angle 

Also called the headtube angle, this is the angle between the ground and the front fork. This is important as it determines the way the front wheel of the mountain bike works and how it impacts overall performance. 

The hand angle can be steep, which is 70 degrees, or slack, which is 65 degrees. The slacker the head angle is, the more stable it will be when you are biking at a high speed. To add, you will also feel more comfortable when you are going downhill. When you are in an uphill terrain, on the other hand, your bike can flop. If the bike has a steep angle, it will do a better job if you are going uphill. When you are riding downhill, it can be twitchy and harder to control. 

Chainstay Length 

It is the distance between the rear axle and your center of mass when you are sitting on the mountain bike. If the chainstay is shorter, this also means that it will be nearer the rider. This will let you be more dynamic to your weight. This also means that it will be easier to get the front wheel off the ground. This will be useful techniques like MTB jump and bunny hop

However, a shorter chainstay is not always a good thing. While it will make it easier to do some mountain bike tricks and techniques, it can also affect stability, especially when you are biking at a high speed. This can also compromise the overall performance of the mountain bike when you are on rough terrains. 

Bottom Bracket Height 

The bottom bracket height is the distance between the ground and the middle part of the bike’s crank. In some manufacturers, they call this the bottom bracket drop. If some cars are lowered, there are also bikes with a low bracket height. You will find this useful when cornering a mountain bike

However, when the bracket is too low, there is a high possibility that it will scratch the ground when the terrain is bumpy or when you get through large rocks and obstacles. If that’s the case, then you should know how to hop the bike properly to avoid the bracket from touching the ground. 

Wheelbase 

It is the horizontal distance between the front and rear axles of the mountain bike. Increasing the distance between the axles will have a positive impact on the stability of the bike. The farther they are from each other, the more stable your bike will be. On the other hand, when the distance is shorter, this can result in being easier to maneuver. 

What Size Bike Should I Buy for my Height? 

Here is a quick look at the right size of mountain bike to buy depending on your height: 

RIDER HEIGHTRECOMMENDED FRAME SIZE
4’10” to 5’2”13 to 14 inches (Extra-Small) 
5’2” to 5’6” 15 to 16 inches (Small)
5’6” to 5’10” 17 to 18 inches (Medium) 
5’10” to 6’1” 19 to 20 inches (Large)
6’1” to 6’4” 21 to 22 inches (X-Large)
6’4” to 6’6” 23 to 24 inches (XX-Large)

The numbers presented above are standard recommendations. There can be slight variations for women riders. It is common for women to be shorter than men, so they might also need a smaller bike to fit their body type. 

Sizing Up and Sizing Down Your Bike’s Frame 

After matching your height to the mountain bike frame size, there are instances wherein you might want to size up or down. This is a matter of personal preference. Whatever you decide on, however, will have an impact on your comfort and the mountain bike’s performance. 

In most instances, for those who size up, they change the size of their reach, which can change from small to large. The stack is not sized up most of the time because a lot of riders would prefer their bikes to be lower. Some also decide to increase the wheelbase a bit because it will make the bike slightly longer. Especially if you have a long torso, then you might benefit from sizing up the mountain bike. 

When it comes to sizing down, on the other hand, you will make the reach and wheelbase slightly shorter compared to what is recommended for your height. This will help to improve your pedaling position, which can result in better comfort and efficiency. A shorter wheelbase can make the bike nimbler, so make sure that you are in a good state of health. If you aren’t in your best physical state, then make sure to read this quick guide on MTB training tips

Is it Better to Get a Bigger or Smaller Mountain Bike Frame? 

It is better to choose a bigger mountain bike frame compared to getting a smaller frame. By sizing up your mountain bike, you can enjoy a more aggressive riding position, which means that you will be more prepared to confront what is on the trail. 

Mountain Bike Sizing Beyond the Frame

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While the frame is the most important consideration when you are sizing a mountain bike, this is not the only thing that matters. To make sure that it fits perfectly, this section will quickly look at the other things that you should consider. 

Size of the Wheel 

The size of the MTB wheels will be equally important. It can make a huge difference on your ride, although, most people do not give much importance to it compared to the frame. This is crucial because it determines rolling resistance. If the wheels are bigger, it will be easier for you to overcome large obstacles. Attack angle, acceleration, maneuverability, and traction will all have an impact on the right wheel size. 

Mountain bike wheels are available in three sizes. The smallest is the 26-inch wheel, which has been the traditional option. Nowadays, it is quite hard to find this. Because it is the smallest, it is also the lightest. It is more agile, and in turn, it can offer better acceleration. If you are looking for a bike that is designed for dirt jumping, this is what you should choose. 

Most of the mountain bikes that you can see in the market today will have 27.5-inch wheels. This can offer the best of both worlds and can be great when it comes to maneuverability. They also have a great grip, making sure of a good ride. 

If you prefer large wheels, on the other hand, you will benefit from a bike with a 29-inch wheel. This is also great for large riders. It is a common choice among downhill and cross-country racers. It might be slower to accelerate, but you will love how it does better when you are on rough terrains. Because it is large, however, take note that it can also drastically increase the weight of your mountain bike. 

Size of the Saddle 

Aside from the frame and the wheels, you also have to consider the size of the MTB saddle. This will make sure that you can sit comfortably. If it is too small, you might end up getting out of your seat especially if you are pedaling aggressively. On the other hand, if it is too large, you will find it awkward to sit and comfort can be compromised. 

Aside from the size of the saddle, the height of the seat is an equally important consideration. Most of the options today will allow you to adjust the mountain bike seat height, which will be great in terms of flexibility. Consider your inseam to determine the right height of the seat at which you will be most comfortable. 

Try Before You Buy 

This is perhaps the most important thing that you should do. There is no one-size-fits-all mountain bike. Aside from your height, your weight, body type, and riding position, among other things, will have an impact on mountain bike frame size.

By having the opportunity to try the bike, you will see how it fits. Try to simulate multiple riding positions. Test the bike for a few minutes and see if you are comfortable with its size. While trying the bike, figure out some of the adjustments that you can do to customize how the bike fits. 

If you are buying online, pay attention to the rules regarding returns and exchanges in case the fit of the mountain bike is not right for your preferences. 

Globo Surf Overview 

Aside from understanding bike frame materials, you should also know its size. The right mountain bike sizing is crucial for comfort and control. It will optimize your performance on the trail. Your height is the most important consideration in making sure that the bike fits. 

More than the frame, however, you also have to consider how other parts are suitable for you, such as the saddle and wheels. The performance of the bike will depend on the total of its parts and not just the frame.

Globo Surf
My name is David Hamburg. I am an avid water sports fan who enjoys paddle boarding, surfing, scuba diving, and kite surfing. Anything with a board or chance I can get in the water I love! I am such a big fan I decided to start this website to review all my favorite products and some others. Hope you enjoy!