Get the Perfect Fit: Ultimate Mountain Bike Frame Size Guide

What size mountain bike do I need?

When it comes to mountain biking or gravel, having the right size frame is crucial for both performance and comfort. A frame that's too small can limit your mobility and control, while a frame that's too large can make it difficult to maneuver and put unnecessary strain on your body. 

So, how do you ensure that you're riding a bike that fits you perfectly?

Here’s a basic chart showing recommended frame sizes based on the rider height:

Bike Size	Frame Size (Imperial)	Frame Size (Metric)	Rider Height (Imperial)	Rider Height (Metric)
XS	13 inches	33 cm	4'8" - 5'2"	142 - 157 cm
S	15 inches	38 cm	5'2" - 5'6"	157 - 168 cm
M	17 inches	43 cm	5'6" - 5'10"	168 - 178 cm
L	19 inches	48 cm	5'10" - 6'1"	178 - 185 cm
XL	21 inches	53 cm	6'1" - 6'4"	185 - 193 cm

 

It's important to note that this is just an example and the size chart may vary depending on the bike brand or model. It's always recommended to check the manufacturer's size chart or visit a professional bike fitter to ensure the perfect fit.

Getting the perfect mountain bike fit

When it comes to finding the perfect frame size for your mountain bike, it's important to consider several factors. Body measurements such as inseam, torso length, and arm length can provide a rough idea of what frame size will work best for you. But, it's also important to take into account your riding style, test riding different frame sizes, and visiting a professional bike fitter for a comprehensive evaluation.

Riding a bike that is the wrong size can cause a variety of problems, such as discomfort, pain, and lack of control. This can lead to decreased performance and even injuries. Therefore, it's crucial to take the time to find the perfect fit for your mountain bike, to ensure that you can enjoy your rides to the fullest.

Let's explore some key dimensions to take into account:

Seat tube length and standover

Seat tube length is one of the most important measurements when it comes to finding the perfect fit for your mountain bike. It's the distance from the center of the bottom bracket to the top of the seat tube, and it gives you an idea of the size of the frame you need.

To check the seat tube length, we recommend to use a bike size chart provided by the manufacturer or by visiting your local bike shop.

Standover height, on the other hand, is the distance between the ground and the top tube of the bike when the bike is standing upright. It's important because it affects how easily you can dismount the bike and how much clearance you have when you're standing over the bike.

To measure standover height, you'll need a friend to help you. First, find a flat surface, like a piece of plywood, and place it on the ground. Next, place the bike on the plywood in an upright position. Have your friend measure the distance between the ground and the top tube of the bike at the point where the top tube is closest to your body.

A good standover height for a mountain bike is about 2 inches (5cm) of clearance. However, some riders may prefer more or less clearance depending on their riding style and personal preferences. It's important to note that standover height is also affected by the width of your tires, so be sure to measure it with the tires you'll be using.

Saddle height

Saddle height is a crucial measurement for finding the perfect fit for your mountain bike. It directly affects your power output and comfort on the bike. A saddle that is too low will limit your power and can cause discomfort, while a saddle that is too high can cause strain on your knees.

The ideal saddle height is a matter of personal preference, but a good starting point is to have your knee slightly bent when the pedal is at its lowest point. This way you'll achieve a good balance of power and comfort. 

Foot position and cleats

The position of your feet on the pedals and the position of your cleats on your shoes can have a big impact on your comfort and performance. Proper foot position and cleat alignment can help you transfer power efficiently and reduce the risk of knee pain and injury.

When it comes to foot position, it's important to make sure that your feet are properly aligned with the pedals. This means that the balls of your feet should be over the pedal axles. You can achieve this by adjusting the position of the cleats on your shoes if you use clipless pedals. 

Cleat position is also important, as it can affect the angle of your foot on the pedal and, in turn, the alignment of your knee. A general rule of thumb is to have your cleats positioned so that your knee is slightly bent at the bottom of the pedal stroke. However, this can vary depending on your riding style and personal preference.

It's also important to note that foot position and cleat position can change over time, so it's a good idea to check and adjust them regularly. 

Women's-specific mountain bike fit and size

Women's bodies are generally smaller and have different proportions than men's bodies, which is why many bike manufacturers offer women's-specific mountain bikes. These bikes are designed to take into account the unique needs of women riders, and provide a better fit for women.

Women's-specific mountain bikes typically have a shorter top tube, a steeper head angle, and a narrower handlebar. These design features help to provide a more comfortable and stable riding position for women. They also tend to have a lower standover height, making it easier to dismount the bike.

Additionally, many women's-specific mountain bikes come in smaller sizes, with frame sizes starting at XS, which can be harder to find in unisex models. This ensures that women of all sizes can find a bike that fits them properly.

It's important to note that not all women will prefer a women's-specific bike, and some may find that a unisex bike fits them better. It's always recommended to test ride multiple brands and models to find the one that feels the best for you.

Kids'-specific mountain bike fit and size

Just like adult bikes, kids' bikes come in different sizes and styles. But, kids' bodies are generally smaller and have different proportions than adult bodies, which is why many bike manufacturers offer kids'-specific mountain bikes. These bikes are designed to take into account the unique needs of kids riders, and provide a better fit for them.

Kids'-specific mountain bikes typically have a lower standover height and a shorter top tube, which allows for a more comfortable and stable riding position for kids. They also tend to come in smaller frame sizes, starting at 12 inches, which can be harder to find in adult models. This ensures that kids of all sizes can find a bike that fits them properly. 

Problems caused by the wrong size mountain bike

Riding a bike that is the wrong size can cause a variety of problems, such as discomfort, pain, and lack of control. This can lead to decreased performance and even injuries. It's crucial to take the time to find the perfect fit for your mountain bike, to ensure that you can enjoy your rides to the fullest.

One of the most common problems caused by the wrong size mountain bike is discomfort. Riding a bike that is too small or too big can put pressure on your body in the wrong places, causing discomfort and even pain. This can make it hard to enjoy your rides, and can even lead to injury.

Another problem caused by the wrong size mountain bike is lack of control. If your bike is too big or too small, it can be difficult to maneuver, making it hard to stay balanced and control the bike. This can be dangerous, especially when riding on technical terrain or at high speeds.

Finally, riding a bike that is the wrong size can also lead to decreased performance. A bike that is too small or too big can make it hard to transfer power efficiently, which can affect your speed and endurance.

AMS favourite methods for choosing your mountain bike (or gravel for that matter) bike frame size

When it comes to finding the perfect frame size for your mountain bike or gravel bike, there are several methods to consider. At AMS, we recommend starting with a basic size chart, talking to your local bike shop, demoing the bikes or similar ones to feel it, and lastly, using the services of a professional bike fitter.

Starting with a basic chart

The first step in finding the perfect frame size for your mountain bike is to use a basic size chart. Most bike manufacturers provide size charts on their websites or in their catalogs that list the recommended frame size based on your height. This can be a good starting point, but it's important to keep in mind that these charts are just a rough guide and may not take into account other factors such as your riding style, inseam, and torso length.

Talking to your local bike shop

Another method for finding the perfect frame size for your mountain bike is to talk to your local bike shop. The staff at your local bike shop have a wealth of knowledge and experience and can help you find the right size bike for your needs. They can also help you test ride different frame sizes, which can be a great way to get a feel for the bike before you buy it.

Demoing the bikes or similar ones to feel it

Demo riding bikes or similar ones is a great way to get a feel for how a bike handles and fits. Many bike manufacturers and bike shops offer demo fleets of bikes that you can rent for a day or weekend. This is a great way to test ride different frame sizes and models, so you can find the one that feels the best for you.

Using the services of a professional bike fitter

Finally, the most accurate method for finding the perfect frame size for your mountain bike is to use the services of a professional bike fitter. A professional bike fitter will use advanced technology andmeasurement tools to determine the perfect frame size for your body. They will take into account your riding style, flexibility, and any current or past injuries. They'll also make adjustments to your bike's fit, such as saddle height, handlebar position, and cleat alignment, to ensure that you have the most comfortable and efficient riding position.

A professional bike fitter is a great option for those who want to ensure that their bike is the perfect fit for their body and riding style. It can also be a good idea for experienced riders who want to improve their performance and prevent injuries.

It's important to note that while these methods can be helpful in finding the perfect frame size, it's still ultimately up to the rider to decide which size and bike feel the most comfortable for them. It's always recommended to test ride multiple brands and models to find the one that feels the best for you.

In the end, all of this is to ride as much as you can, enjoy bike life and do it in style. In All Mountain Style