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How To Choose The Best Mountain Bike Frame Size



October 28, 2020

Having a mountain bike, also known as a mtb, that fits you properly makes all the difference when it comes to your comfort and safety. The right size mountain bike is not only good for you as the rider, but also may help other people on the road because you’ll be better able to best ride the bike properly around them.

If you’re wondering how to go about picking the right size mountain bike you’ve come to the right place. Throughout this article we’ll talk about how to choose the right size bike you’ll want for your height, as well as what happens when you try and ride a bike that’s way too large or small for your body. We’ll also answer some frequently asked questions so you understand what you need to know about bike sizing to better find and buy the best mountain bike for your size.

Keep in mind that most of the information we’re going to go over in this article apply for both mountain bikes and road bikes. There may be some slight differences when it comes to the sizing of mountain bikes, particularly when referencing the chart below, but overall you can take this information to help you when it comes time to getting your mountain or road bike. Just remember that when you search for your bike that manufacturers usually have their own chart you can reference when picking the size bike.

How to Choose the Right Bike Size

The easiest way to figure out the bike size you need is to measure yourself so you know what your length is and comparing that length to a mountain bike size chart. This is an important step to take before you make any big purchase and get the bike because you don’t want to have to return the bike once you have it in your hands. Remember that a mountain bike’s length is measure from the centre of the bottom bracket to the top of the seat tube.

If you check out the chart below, you can see that your rider height (in either inches or centimetres) indicates what size mountain bikes you need to be considering.

For example, if you are between 4’10” and 5’2″ tall you would be best getting an extra small frame size which is within 13 inches to 14 inches. If you’re much taller, between 6’2″ and 6’4″, you need to look into frame sizes that are measure as large. A large frame size is anywhere between 19 inches and 20 inches.

bike frame size chart - metric and imperial

Credit: https://www.evo.com/guides/mountain-bike-fit-size-geometry

One good practice when it comes to making sure the mountain bike is the right fit is to get on the seat so you can have a feel of what it would be like when you’re on top of the bike. Of course, this isn’t the same as when you actually use the bike, but at least you would have an idea of what to expect before you buy it so you don’t have to worry about sending it back. If you plan to search online for your bike you likely won’t have this option.

You should also try and keep your head straight when it comes to the different parts of the bike that matter most to you. In addition to the length of the bikes you’re looking to get, you should also consider the saddle comfort, the angle of the frame, and the overall build quality of the bike you want to get.

What Happens if a Mountain Bike is Too Big for Me?

If you find the bike you’re using seems to be a little too big you might run into some issues when riding it for long periods of time or over rough terrain. The bike fit is the most important aspect of any bike and if you’re trying to use a bike that’s too large you’re going to have a problem controlling it. When we’re talking about bike fit, we’re specifically referring to the distance from the saddle to the handlebar, otherwise known as the reach.

You can adjust the reach if the distance is too far for your riding style by moving the stem up or down on the steer tube or by changing the length or angle of the stem. However, if the bike size frame is too large for your height there’s not much more you can do. Also, if you adjust the stem or seat tube too much you’re going to affect the weight distribution of the bike, resulting in a bicycle that’s not as easy to handle.

What Happens if a Mountain Bike is Too Small for Me?

If the mountain bike size is too small for your height you’re going to have a less comfortable ride, especially when it comes to the amount of leg room you have. If you have longer leg length then the geometry of the bike allows, you’re going to have to try and ride the bike in a more cramped position.

Bike sizes that are designed for shorter riders have frames sizes that are designed with that height in mind, meaning that you’re putting your comfort and safety at risk when you use bikes that have a bike frame that’s too small for you. You need to check things like your standover height, the mountain bike frame size, the height of the seat post, and the position of the bottom bracket to ensure the bike if going to be the right choice for you.

what is my bike frame size

Frequently Asked Questions

To help you find the best mountain bike or road bike for your rider height, we’re going to go over some of the questions we’re asked most often from riders who are trying to find the right frame size for the new mountain bikes they’re considering buying.

What size bicycle is right for my height?

While everyone is different, there are a number of useful resources you can find that make bike sizing easier. This includes a bike chart or applying a simple calculation to figure out the frame size you should get. This calculation is your leg inseam in cm x 0.66. For example, if you leg inseam is 85 you would need to multiply that by 0.66 which would give you a frame size of 56 cm or 21 inches to 22 inches.

What are the best frame sizes for younger children?

It can be difficult figuring out bike sizing for a young rider because you know that their rider height is going to be different in just a few years. However, it’s always best to go with a bike that fits them properly and have them ride that while its still safe to do so. Slightly smaller bikes are safer than bikes that are too big, even if they don’t fit as comfortably as one that’s the perfect size.

How is a road bike different from a mountain bike when it comes to size and fit?

If you do a quick search online you’ll discover that there are sizing charts for both mountain bikes and road bikes. This is because there are some differences when it comes to bike sizes due to how the bikes are manufactured and used. While a medium size road bike would work for you if you’re 5’6″, you may need a small size mountain bike at this size.


We know how long the search for the right bike can take, especially if you’re trying to find something perfect for your budget and needs. However, it’s important that you keep your head in the game and take your time by first identifying the proper bike size for your leg length and overall height. It doesn’t matter how comfortable you feel in the saddle, if the bike isn’t the right size you’re going to suffer in the long run with a less enjoyable experience.

You might also be interested in our best aero bar article.

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About the author 

Beastie Bikes Pete

Hi I'm Pete. I'm a passionate mountain biker in Australia. I enjoy writing about biking as much as doing it......almost!

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