What Size Mountain Bike Should I Get – Size Chat & Frame Geometry

What size mountain bike should I get is a frequently asked question while deciding between mountain bikes. It would be best to get the bike that matches your body requirements, like your height and overall body shape. A bike with perfect setup and fitness is quite easier and joyful to ride on the trails. You will feel more comfortable and can exert more control on this kind of mountain bike. The bikes with poor setups are twitchy, nervous, and highly uncomfortable to ride.

Normally, people prioritize standover height and seat tube length while choosing the mountain bike for them. Still, you could not ignore other factors like reach, stack, wheelbase, effective top tube, head tube angle, and chain-stay as they also play a crucial role in getting the perfect sized mountain bike. You can easily go through these things by looking at the mountain bike geometry heading in this article.

If you want to have a comprehensive overview of mountain bikes, this article is highly recommended for you, or you can also share it with your dear ones who are looking for a mountain bike. The aim of this article is to educate even the slightest of detail about MTB. So that you just buy one and put the smart MTB helmet on and ready for your expedition.


What Size Mountain Bike Should I get?

Most of the manufacturers normally categorize the mountain bikes under small, medium, and large headings. The basic difference between these sizes is the size of the frame. The other things like suspension, wheel size, and geometry mostly remain the same. However, some brands also change the sizes of these things along with the sizes of the bikes. Traditionally, the bikes were sized according to seat tube length adjustment. Nowadays, the manufacturers are giving recommendations for bike sizes according to your height.

Generally, the best way to select the right-size bike is through the mountain bikes’ size chart. It is a baseline that helps you find the right-size bike according to your height. It will help if you go through the specific brand’s size chart as the design philosophy and geometry vary from brand to brand. The classification of bikes according to the sizes of their frame might be good, but we should also consider the other factors like geometry and skills level while selecting the right-size bike. We will also discuss these things below to clear your idea about the mountain bike size. Let’s have a look at the standard mountain bike size chart.

Rider height (in)Rider height (in)Frame size
4' 10" - 5' 2"13" - 14"XS
5' 3" - 5' 6"15" - 16"S
5' 7" - 5' 10"17" - 18"M
5' 11" - 6' 1"19" - 20"L
6' 2" - 6' 4"21" - 22"XL
6' 4" +23" +XXL

Mountain Bike Geometry

The overall shape of the bike is called its geometry. It is a combination of several important measurements. The style, fitness, and feel of the mountain bike are closely associated with these measurements. These also depend upon the kind of terrain your bike has to perform on. The two most measurements among these are Reach and Stack. What size mountain bike should I get? To answer this question first, let’s have a look at these geometric features one by one.


The horizontal distance between the center of the head tube and the bottom bracket is called its reach. This is considered the most important component of your mountain bike as the length of the cockpit wholly depends upon it. If the reach is too long, you will have to lean and stretch out while riding the bike.

What Size Mountain Bike Should I Get


The vertical distance between the center of the head tube and the bike’s bottom bracket is called its stack. It is a measurement of the height between the handlebar and the seated pedaling position. You can easily adjust it by lowering or raising the handlebar height. If you compare stack with reach, then reach will always trumps stack.

stack is important factore while choosing  Size Mountain Bike

Head Tube Angle

The angle between the front fork and the ground is called the head tube angle. It is the key parameter for determining the behavior of the front wheel. The head angle comes in two forms slacker (lower) or steeper (higher). A slacker head angle is good for stability at high speeds and on downhill terrain. The bike will steer lazily from the top, and you need to keep changing your body positions to handle the terrain properly. To stop yourself from wheeling off the trail, you will have to keep your weight on the front tire. On the other hand, the steep head angles will be highly suitable for uphill terrain. At this angle, you will feel like the front wheel has been planted in front of you. Thus, if you have to pedal uphill, you should choose a bike with a steeper head angle. But if you have to pedal downhill, you need to take the bike with a slacker head angle.

what is head angle of a mountain bike

Chain-stay Length

The distance between the rear axle and the rider’s center of mass is called the Chain-stay length. It is usually set according to the personal preference of any rider. Short chain-stay means the rear wheel is closer to the rider. You can act more dynamically with your weight in this position, and you can easily let the front wheel off the ground. But it will reduce your wheelbase length and make you unstable at high speed and over tough terrain. Thus, the shorter chain-stay is good for wheeling, and the longer chain-stay is good for overall stability.

What is Chainstay length

Bottom Bracket Height

The distance between the center of the cranks and the ground is called bottom bracket height. This property of the mountain bike measures how lower or higher is your center of mass. If you are riding on the bike having a lower bottom bracket, then from turn to turn, you have to do a transition as the earth would not be flat or smooth on the trail. If you don’t do it, you might clip rocks, roots, or logs with your bike. In this scenario, you also have to keep the pedals on the upper side while passing over the obstacles.

boottom bracket height is important factore while choosing  Size Mountain Bike


There are many factors like Reach, Head tube angle, and chain-stay, which impact your wheelbase length. The wheelbase is the culmination of all the factors mentioned above. Increase the distance between the rear and front-wheel axle. It will increase the overall stability of your bike, while shortening the wheelbase will increase the maneuverability of your bike. The increasing or decreasing distance might be coming from the head tube angle or chain-stay.

wheelbase important to consider while thinking what Size Mountain Bike Should I Get

How to get a perfectly fit mountain bike?

Many skilled riders think they are riding on a perfectly sized mountain bike. But few basic changes question the perfection of their mountain bike size. The minor changes in bikes like tire pressure and suspension give you a wholly different experience of riding. While riding on the bike, our body parts make contact with three different mountain bike parts. Hands-on the bar, bum on the saddle, and feet on the pedals. The relative positioning of these areas lets you know how to set the bike size perfectly.  Other variables like seat angle, top tube length, crank length, bar height, stem length, saddle angle, and distance from the bottom bracket to saddle also influence. Thus, the best way to get the perfect size bike is to ride on the bike from time to time after making some changes. Let’s have a look at some basic guidelines for bike fitness.

Seat Tube Length and Standover

Seat tube length and standover factor for MTB bike size slection

The distance between the ground and the top tube is called standover height. The standover is an important aspect of measuring what size mountain bike should I get as it allows the clearance to your crotch. There must be an acceptable standover gap. To check this gap, you should stand back over the bike and ensure that there is at least a distance of 1-inch between the top tube and your crotch area

Saddle Height and Crank Length

Saddle Height and Crank Length of MTB bikeUsually, mountain bikes come in 170mm or 175mm cranks, which works very well for most riders. But if you have short legs, then you might have to bend your knees excessively. To get rid of this problem, you must set the saddle so that you can fully utilize your power and efficiency. If it is too high, then your hip might rock from the side, and if it is low, your muscle might not deliver power efficiently. You must set the saddle at such a height that when your heels on the paddle are at the bottom of the pedal stroke, then your leg must be in fully extended form. In this way, your knee would never lockout.

Top tube length and reach size of MTB bike

Top Tube Length and Reach

Top tube length is one of the most important factors to consider if you want to increase the level of comfort on your bike. Top tube length is closely associated with the reach of the bike. The reach will give you the standing up or descending position. As far as the selection of the position is concerned, most of the cross-country riders like to have a stretched-out position, but the beginners like to have an upright for extra comfort. you should set the position which works best for you.

Seat Angle and Top Tube Length

The cranks in the mountain bikes are usually lying at an angle below the saddle. If this is not the case, you might put more weight on your arms while leaning forward. You can set these things at different angles, whichever best suits you. However, if you push the saddle too far back, there will be too much less weight on the front steering wheel, and suspension will not work efficiently.

Foot positions and Cleats

The ball of the foot must be in a good position above the pedal. If you place the cleat directly under the foot’s ball, it would be an ideal case scenario. You can adjust it by moving back and forth, but you must ensure that your shoes are not hitting the cranks during pedaling. Nowadays, clipless pedals are coming into the market, which lets you set your foot at a natural angle.

Pitfalls Of The Wrong Size Mountain Bike

If you get the wrong size mountain, it might cause many problems, especially your health. It could wrongly stretch out your muscles and might inflict injury in the worst-case scenario. Normally, the pain and aches are simply because of inefficient muscle support. You can resolve this problem by regular training and building your stamina. However, some of the most common ailments and their causes are given as:

Knees pain: If the saddle is too high or low, then it might inflict knee pain while riding. It also occurs if the shoe cleat is poorly adjusted.

Back pain: If you feel back pain during or after riding, it indicates the wrong frame size. It usually occurs if there is poor muscle core support. There is no immediate solution to this problem. You can gradually resolve this issue by keep changing the position of handlebars and reach. A lot of riders have resolved this problem by moving stem up and down.

Pain in shoulder, arms, and neck: These three areas are covered together because the pain in these areas mostly occurs due to the same reasons. The basic reason behind the pain in these areas is that it is too big or too small if you use the bike. These usually occur if you sat too far forward or too far back. It will curl your shoulders and stops you from holding the bar effectively. You can resolve this problem by going upsweeps or back-sweep on the bar. Anatomically shaped grips are also good for providing support to your hands.

Hips: The riders’ most common problem while riding the mountain bike is a pain in the hips. It occurs if the saddle is not in a good position, like it may be too high or too low or too far backward or forward. If the saddle is in such a position that you could not do right paddling, then you must change the position of your saddle.

Although everyone has a different physique like some people have long legs and arms, some people have short. Thus, you must select the correct frame size and then make moderations in its parts like in stem, bar, saddle, and seat post.

Components Of Mountain Bikes That Impact Your Comfort And Control

Many components have a great impact on the comfort and control of the riders. Let’s discuss these by one.

Tires: The tires’ quality and pressure let you allow how much comfort you can feel and how much control you can exert on the bike. Dually compounded tires having high TPI(threads per inch) could easily deform on rough terrains and let you grip better without having much rolling resistance. On the other hand, the cheap tires might have less grip and lose traction under wet conditions.

Grips: Soft or sticky handlebar grips will provide extraordinary comfort, absorb vibration and let you feel extraordinary comfortable on rough terrains.

Saddle: High-quality surface material on the saddle will make you feel comfortable on the bike. You should use such a material which lets you easily move on the saddle. Avoid fancy and embroidered graphics on the material as it is not conducive.

Pedals: The efficiency of the riding wholly depends upon pedals. If you have stiffed soled shoes having cleats fixed to clipless pedals will make you extraordinary comfort. If the cleat is poorly position, it might cause a problem in your knees. Most of the riders set the cleats at the dead center, while some allow free float movement.

Sizing Up Or Sizing Down The Mountain bike

When to size up the mountain bike?

In sizing up the mountain bikes, the reach is the most important factor to consider than other parts like a stack. If you have a longer torso, you would want to size up the mountain bike to fit your position on the bike. In this regard, the reach will play a primary role in sizing up your mountain bike. You will also have to maintain the position of your hips. If you are not tall enough, then a longer than taller bike will be good for aggressive riding in the mountains. Overall, if you have a flexible and longer torso, then the mountain bike’s sizing up will be the ideal option for you.

When to size down the mountain bike?

In the smaller-sized mountain bike, you will have a short reach and wheelbase. In this case, you will get the lower standover height and extended seat bit. If you have longer legs than average and like to be upright, then the shorter-sized bike would be good for you. Generally, the shorter-sized bikes are more comfortable if you have to use them for a longer time.

Frequently Asked Questions

What is the difference between a road bike and a mountain bike?
There are a lot of differences between road and mountain bikes. If you are a road bike rider and looking for a mountain bike, you need to go through many things. Usually, mountain bikes have a smaller seat tube but longer top tube length than road bikes. There are also other differences like grip, durability, pedaling, chainstay, wheelbase, etc.
What kind of mountain bike is good for women?
Recently, a lot of women-specific mountain bikes have been introduced in the market. The women’s body shape is slightly different from men’s, so you need to make some changes in the design of their bikes. Most women-specific brands use the same frame size with little bit changes in touching, like finishing kits specially designed for female riders. Many things are similar in women-specific bikes like lighter sprung forks, thinner grips, narrower bars, and women saddles. These things are not only beneficial for women but also men having small hands and narrow shoulders.
What kind of mountain bike is good for kids?
For the youngsters, the rules of the mountain bikes are almost the same except few extra considerations. The top tube clearance and the reach are very important in this regard. The wheel diameter for these kinds of bikes is usually kept between 12 to 26 inches. The child must have access to the ground while seated for control and safety. The brakes must also be soft and work very well. Moreover, it would help if you preferred twist grip-type gears in these bikes.
How the mountain bike geometry impacts the rider?
The geometry is quite important in dealing with mountain bikes. The angles at which tubes are joined together to form the frame have extraordinary importance in this regard. The geometry of the bike also depends upon the riding you have to do with the bike. For cross-country riding, the bikes having steeper geometry will be perfect. Other bikes like endure and trail biker normally has slacker geometry.

By going through deep research and testing about the mountain bikes, we have answered the most asked question about the bikes, which is what size mountain bike should I get. After going through this article, you will be quite clear about all the properties of mountain bikes, and you will be damn sure about what should be the height, length, and size of your mountain bike.

Leave a Comment