Mountain Bike Sizing Chart: How to Fit a Mountain Bike Properly

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For the perfect handling, safety, and comfort, you have to look for the proper mountain bike size chart for yourself. When you know very well about your inseam and height measurements, you might determine what real size frame would be quite comfortable. Between these two measures, the inseam is the most crucial one.

You usually measure mountain bikes in frame size (that is inches). It’s the distance that’s from the middle of the crank to the frame top at a seat tube.

Related: Hybrid Bike Size Chart for Men, Women & Kids

Mountain Bike Sizes Guide (Men, Women & Kids)

While purchasing a mountain bicycle, the fit is a very crucial element while it does come to comfort. When you are comfortable, you will keep riding.

The mountain bike, which is quite small, would quickly become uncomfortable, causing handling issues, and would irritate you as well. A mountain bike that’s quite big is also not comfortable to ride. It might be harmful if you try hard to manage the size, particularly on rough terrain.

These bike frames are always in inches. Their sizing also goes from 13 to 15 inches; that’s what somebody on the smaller size may ride, up to twenty-three inches or above. It is the best for a tall rider.

Generally, a mountain bike would be almost the proper size in case its top tube (its bar which goes between its handlebar and seat) does leave two to three fingers space just below the groin (that is your pants inseam) when you straddle the bike along with the feet flat on a surface.

When there’s not any top tube, then sit on your seat. You would easily touch the floor, but just on the tippy-toes, and then might be only on one side. You need to note that these bike frames are typically smaller than the road bike frames size. Plus, the small size is also to make them more straightforward for you to control on the rough terrain.

In case you can put your feet on the floor whilst you’re sitting on its seat, your bicycle is a bit small, or its seat is low.

While sitting on your seat, you must be able to put your feet quickly on the pedals. Also, you could reach the handlebars easily without being scrunched quite close and stretched out a bit far when you lean a bit forward.

Mountain Bike Sizing for Men

cycling, sport, mountain bike
HeightInside legMale’s bike size
147cm to 152cm/4’10inch to 5’0inch66cm/26inch13inch (X Small)
152cm to 160cm/5’0inch to 5’3inch69cm/27inch13inch , 14inch (X Small)
160cm to 170cm/5’3inch to 5’7inch71cm/28inch15inch, 16inch (Small)
170cm to 175cm/5’7inch to 5’9inch76cm/30inch17inch, 18inch (Medium)
175cm to 180cm/5’9inch to 5’11inch79cm/31inch18inch, 19inch (Medium, Large)
180cm to 188cm/5’11inch to 6’2inch81cm/32inch19inch, 20inch (Large)
188cm to 196cm/6’2inch to 6’5inch86cm/34inch20inch, 21inch, 22inch (X Large,Large)
196cm+/6’5inch+91cm/36inch23inch, 24inch (XX Large)

Mountain Bike Sizing for Women

biker, mountain bike, jump
women mountain biking

Fundamental uses and features of the mountain bikes include:

  • Majorly used for the rugged riding in the steep terrains and off-road conditions.
  • They’re perfect for the off-road riding because they’ve got a larger frame, larger tire diameter, many gears, and a complete braking system.
Rider Height
(Inches & Feet)
Rider Height(CM)Frame SizeFrame Size
4′ 10inch to 5′ 2inch148 to 158X Small33 to 35cm
5′ 2inch to 5′ 6inch158 to 168Small38 to 40cm
5′ 6inch to 5′ 10inch168 to 178Medium43 to 45cm
5′ 10inch to 6′ 1inch178 to 185+Large48 to 50cm

Mountain Bike Sizing for Kids

bikes, kids, children
Kids Biking

Trying to learn riding is quite sturdy without the mountain bike too small or too big! Choosing the correct bike size might be a bit tougher for kids because the size of its wheels tells the right bike size for children as compared to the frame. There is the growth spurt element that could render the bike unsuitable just after some time!

While you are picking a mountain bike for a kid, children’s bike sizing chart is only about the wheels. Too small or too big wheels would inevitably result in many problems like controlling and balancing the mountain bike, so it is vital to look for the proper wheels to suit kids’ measurements.

Wheel SizeAge of Child
(in Years)
Height of Kid
(in Inch)
Height of Kid
(in cm)
Balance2 to 42′ 11inch to 3′ 5inch88 to 105
12inch3 to 53′ 3inch to 3′ 8inch98 to 112
14inch4 to 63′ 5inch to 3′ 10inch105 to 117
16inch / 18inch5 to 83′ 8inch to 4′ 2inch112 to 127
20inch7 to 93′ 10inch to 4′ 6inch117 to 136
24inch8 to 114′ 2inch to 4′ 9inch127 to 145

What Is Important to Look Out for When Choosing the Right Size?

Measurement of My Height

Along with the shoes off, you need to stand straight against the wall, put your legs together, and shoulders back. Now, take a pen for making a tiny sign on the wall just above the head – ensure you grab your pen parallel to the ground. You need to measure from the ground to the mark, in inches, feet, or centimeters.

Measurement of My Inside Leg Length

Along with your bare feet, stand straight with the back against the wall. Put a ruler or book between both legs, level with the crotch. Now, measure from the ground to the top of your ruler or book, in feet, centimeters, and inches (it is more straightforward if your friend assists).

Sizing Down or Sizing Up a Mountain Bike

As you have already measured your height to the mountain bicycle sizing chart, and you are completely ready – what should you do next? Often you are actually in between the mountain bicycle sizes. Here are some important tricks on when to size down or size up the mountain bike if you are in between mountain bike sizes.

What to Do for Sizing Up

While it does come to the mountain bike size chart, Reach does tend to be what alterations more from Large to Small as compared to Stack.

Every other mountain bike is trying to be quite low to purchase the biker range of the motion in the bike’s cockpit. Hence, you will see different bikes along with some increment in Reach. There is a corresponding small increment in the wheelbase because the entire bike itself does get a little longer. Thus, you get maximum advantages (& pitfalls) of the long mountain bike.

Plus, when you have a proportionally long torso, you would have to size the bike up for getting some neutral fit, as Reach is what is impacted by the size. Range of motion and flexibility in the hips is so much crucial to think about.

In case bending over & touching the toes is just as a tall order, the longer mountain bike is more taxing for maintaining an aggressive and low riding position. While, in case you know very well the major difference between the Lotus Pose and the Tadasana Pose (also known as you are the supple yoga leopard), the bigger size would reward you a lot with more aggressive and flexible riding position.

In short, when you are long and flexible in the torso & like to monster-truck on the terrain as compared to flick or whip the way around this, size your bike up.

What to Do for Sizing Your Bike Down

Oppositely, a small-sized bike would have a short Reach as well as a bit short Wheelbase. The stand-over height would be a bit lower. So, you may need to extend the seat-post a tad for getting to the pedaling position. However, it is a bit little consideration while it does come to be between two sizes. In case you have got long legs, lacking flexibility, or likely to be pretty upright, you might feel ease on the smaller size.

In addition, a shorter Wheelbase would ride quite nimbly, and whilst the larger cockpit gives an aggressive riding, aggressive and low riding positions are a bit tiring. Hence, you need to see your fitness, ride length, and endurance. Shorter mountain bikes are simpler to ride for a longer time.

In short: when you like a whippy and nimble ride, are a tad less flexible, are short in the torso, and are trying for a casual bike riding position, then size the mountain bike down.

Demoing Mountain Bicycles

Now, as you know very well, what occurs if you size a mountain bike down or up, just go and test a few bikes! Such as two medium shirts from the brands that do not fit the same, same mountain bikes from a few brands would also feel and fit differently.

You might size the bike up with one brand & size down with another one. Hence, just go out with a clear mind, a nice notion of your bike riding style & how you would use the mountain bike, & look for a perfect fitting mountain bike for yourself!

Geometry Measurements of Mountain Bike

Mountain bicycle geometry is typically the shape of a bicycle. The whole geometry and shape of the bike are made with a lot of important and different measurements.

Such measurements are crucial while discussing the feel, fit, and design of the mountain bicycle. They are proportional to your style & terrain; the bike is made for riding on. These two major measurements will impact the way in which your mountain bike would fit are Stack and Reach.

You need to remember that whilst such terms always come from a terrain, triathlon and time trial world. These numbers will not port over even from the tri-bike to the mountain bike.

  • Stack
  • Chainstay Length
  • Wheelbase
  • Reach
  • Head Angle
  • Bottom Bracket Height

Mountain Bicycle Reach

The mountain bike reach measurement is a horizontal distance that is between the bracket (below) and the head tube (center). It’s arguably a very crucial figure for the bike fit as it impacts the whole length of the bike’s cockpit while you are standing on its pedals & how much motion range in the hips you would use up for achieving a strong and good riding position. A bit long of the reach would make you stuck stretched out and leaned over. A bit short cockpit will make your weight bias shifting too quickly that will leave you in such a position that is just upright.

Mountain Bike Stack

The second crucial geometry measurement for mountain bikes is the stack. It is a vertical distance that is between the head tube (center) and the bracket (bottom). It’s a gauge of the seated pedaling position. It is also handlebar height.

You might adjust it to a degree, along with the headset spacers and handlebar increase for more stack height. Also, for the mountain bike, where geometry depends on an aggressive standing riding position along with its seat down, the Reach does trump Stack like a basic fit dimension.

Head Tube Angle of Mountain Bike

Head tube angle, or head angle, is an angle between surface and front fork of the mountain bike. Though, there’re some other parameters as well that go into what does make the front wheel perform, (trail, fork offset, etc.).

It’s the main major metric which the industry typically uses for determining the front-wheel properties. The “slack” bicycle head angle is the lower number (example: 65°) relative to the “steep” head bike angle (example: 70°). The slacker head angle would, generally, be quite stable at higher speeds and feel pretty comfortable on some steeper terrain (downhill). Conversely, the mountain bike would steer slowly & flop on the uphill terrain from side to side.

You would have to make different body position alterations for tackling steep uphills, just like keeping the weight on the rear tire. Now, you do not wheelie off the terrain. Conversely, mountain bikes with the steep head angles are like a front wheel that’s planted & steer a bit nimbly on the uphill terrain. It feels unstable and twitchy on the fast downhill path.

When your inclinations are towards the pedaling uphill, then you would choose a mountain bike with the steep head angle in case you head down.

Chainstay Length of Mountain Bike

Mountain bike Chainstay length is very much personal to each biker. The measurement determines the distance of the biker’s middle of mass & the back axle. Mountain bikes with shorter chainstays offer the back wheel closer to the rider.

Shorter chainstays let the rider be quite dynamic along with the weight. It means simpler wheelies and manuals & comfort of getting the forefront wheel off the road. It does come at the cost of whole Wheelbase length that contributes to the stability at high speed & over some rough terrain. (You can imagine that the unintentional wheelies when going uphill are not typically the desired trait.)

When you need your mountain bike to ride a bit nimbly & like manuals and wheelies, short chainstays are very good for you. If you choose stability, then go for a mountain bike with long chainstays.

Bottom Bracket Height of Mountain Bike

The lower Bracket height of the bike is a distance between the middle of the cranks & the floor. There are a few manufacturers who refer to the “Bottom Bracket Drop,” that’s a vertical distance between the bottom bracket and wheel axles.

They also measure similar traits of a mountain bike; that’s how low the middle of mass is. The mountain bikes along with bottom bracket corner like they are on the rails & transition effortlessly. Here, the tradeoff is the earth is not flat, and paths are not usually smooth. If your bottom bracket is a bit low, then you would clip rocks, logs, or roots you are struggling to hop over. When you are a savvy and skilled biker, you might make sure that your pedals are not down while passing over hurdles.

However, it does not mean pedaling over the rough terrain. It might be tough to do if your brain is hungry for oxygen or you are traveling at high speed.

Mountain Bicycle Wheelbase

There’re so many different elements that contribute to your mountain bike’s wheelbase length that include Chainstay Length, Head Tube Angle and Reach. The total wheelbase is about the culmination of these elements.

The gist of a wheelbase is an increase in the distance between rear axles and your front. It increases stability. On the other hand, the shorter wheelbase would make a mountain bike a bit maneuverable. You need to see where that enhanced wheelbase is actually coming from (Chainstays? Head tube angle?) & reference these measurements to check how that would additionally impact the entire ride of the mountain bike.

Mountain Bike Sizing FAQ’s

How is the mountain bike-sized?

A mountain bike is typically measured in inches, and/or using the L/M/S system. You can calculate the frame size of MTB by checking the seat tube length, from the middle of the forefront chainring to the tube top (here the seat post actually inserts).

An MTB frame differs a lot across styles and models. Hence, to keep the sizing consistent, bike manufacturers usually use the virtual measurement of a seat tube. Sizes might differ a bit between bike manufacturers.

I am between sizes, so which bike size must I buy?

Suppose your bike measurements suggest that two sizes are appropriate. So, in this case, it is totally your choice. However, most bike riders would pick the large size. The mountain bike, along with a bit bigger frame, is simple to handle as compared to one that does feel cramped.

Also, you might fit a short stem when necessary, to decrease the reach towards the handlebars. On the other side, fitting a longer stem can adversely impact the handling of a mountain bike.

Which mountain bike wheel size is perfect for me?

Mountain bicycles are there in a large variety of wheel sizes. They have distinctive advantages and characteristics. It depends on the type of riding you would be doing.

26-inches Wheels

These are the most recognizable mountain bike wheels that are now unique on the new mountain bikes. Also, quite maneuverable, these struggle hard to carry high speed on rough terrain. There are different new modern mountain bikes with 26” wheels that are for freestyle riding or small frame sizes. You would only see teenage mountain bikes with 26-inches wheels.

27.5-inches (650b) Wheels

This is the most common wheel size, as they offer a great balance between rollover and cornering speed. You can use them for a large variety of riding styles. These wheels suit a lot of riders’ requirements.

27.5-inches+ (Plus-size, 6Fattie) Wheels

These wheels are perfect with 2.8-inches and 3.0-inches width bike tires, on the 27.5-inches rim. Such a combination offers them a whole diameter to 29-inches wheels.

They might be perfect to 29er motorbikes with BOOST axle spacing that is on the back wheel and fork. Although they are a bit slow to accelerate, 27.5-inches+ wheels provide better cushioning and grip. They are perfect for the hardtails. You would see them on the electric MTBs as well.

29-Inches (29er) Wheels

These are the fastest-rolling wheels ever. Small riders might find them tough to handle, but professional mountain riders love these for conquering rough grounds at high speed. These wheels are famous for cross-country, enduro, and downhill riders.


That is a lot of information about mountain bike size chart, and though we have just covered the basic things, this must give you background to choose a proper mountain bike size. There’s still no alternative for getting out there & test some bikes. While this comes to selecting some mountain bike, there is always an intangible and unexplainable connection to a specific ride.

It simply fits & feels right. Hence, take this information with a grain of salt, put your legs over some bikes & just go ride! You need to check a mountain bike out carefully and must have a test ride!

Hi! My name is Dario Lemut and I am the Founder of Cycling fanatic with over two decades of experience on all types of terrain. From long-distance races to rugged mountains. Sharing my experiences and knowledge on my popular cycling website, I'm helping fellow riders to discover new routes and adventures.

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