Choosing a Mountain Bike by Size: The Ultimate Guide

When you ride a mountain bike, a properly sized frame is essential for your comfort and safety. Riding a poorly sized frame, whether it is too big or too small, can be uncomfortable and make handling and control of the mountain bike dangerously difficult. Knowing your inseam and total reach measurements, in comparison to the mountain bike’s frame, will ensure that your mountain bike is a perfect fit.

4 factors determine what type of mountain bike you should buy according to their size. They are:

  1. The elevation at which you would be riding your bike
  2. How often you ride your mountain bike
  3. How much distance you cover in a single ride and finally
  4. Whether you ride your mountain bike for fitness or racing.

To size the frame of your mountain bike use the following steps:

  • Step 1: Measure your inseam length in inches
  • Step 2: Use your inseam length to calculate the top tube or seat tube length
  • Step 3: Perform a Stand-Over Test
  • Step 4: Adjust the Handlebar
  • Step 5: Level your seat angle
Three Mountainbikers Having a Break

A good option is to go to a bike shop to take advantage of a professional fit system, which involves taking body measurements as well as adjusting the mountain bike so you get a perfect fit. But if you order your mountain bike online, have a store that has less knowledge, or you want to know more about the size of a mountain bike please read on.

How do I know What of Size Mountain Bike I Need?

Check out the table below that shows the size for men:

Your Height
Your Inseam Length
Men Bike Frame Size
134 cm – 150 cm
 12″ frame with 24″wheels
150 cm – 160 cm
25″ – 27″
63 cm – 69 cm
13″ – 15″
160 cm – 170 cm
27″ – 29″
69 cm – 74 cm
15″ to 17″
170 cm – 180 cm
29″ – 31″
74 cm – 79 cm
17″ to 19″
180 cm – 190 cm
31″ – 33″
79 cm – 84 cm
19″ to 21″
190 cm+
33″ – 35″
84 cm – 89 cm
21″ to 23″

What Size Mountain Bike Should Women Ride?

Women have 40% less upper body muscle mass than men. This translates to significantly less upper body strength. Most female mountain bike riders rely on the strength in their legs to control their bikes.

Check out the table below:

Inside leg
Women’s mountain bike size
’10”-5’1″ / 147 cm -155 cm
26″ / 66 cm
13”, 14″ (X Small)
5’1″- 5’3″ / 155 cm -160 cm
27″ / 69 cm
13”, 14” (X Small)
5’3″-5’5″ / 160 cm -165 cm
28″ / 71 cm
15”, 16″ (Small)
5’5″-5’8″ / 165 cm -172 cm
30″ / 76 cm
17″, 18” (Medium)
5′ 8″+ / 172 cm +
31″ / 79 cm
19″ (Large)

How to Size the Frame of a Mountain Bike?

Step 1: Measure your inseam length in inches

Stand up and spread your feet 8 to 10 inches (20 to 25 cm) apart, as if you were on a mountain bike. When you are sizing a mountain bike, make sure to measure in inches. Next, you must measure from the inside of your foot up to your crotch, where your legs meet your waist. Like the seam on the inside of your pair of jeans.

You need to measure the distance from the bottom of your foot to where your mountain bike’s seat should be. Then, you must place a book vertically between your legs, touching your crotch. The essence of this is to simulate a mountain bike seat.

While holding the book in place with your hands, you must have a friend measure from the top of the book to the floor and record these measurements for later. The book should be held between your upper thighs just as you would seat on a mountain bike. Make sure that the book has a thick spine, this will help you get better measurements. You can take this measurement several times and record the average for a more accurate number.

Step 2: Use your inseam length to calculate the top tube or seat tube length

If your bike shop gives frame sizes by seat tube length, take your inseam and multiply it by 185. The resulting number is the recommended distance between your seat and the middle of the crankshaft. The crankshaft is the circular piece the pedal rotates on.

Multiply your inseam (in inches) by 67, then subtract 4 from the answer to get the length of your top tube. You must use the top-tube for your measurement. Seat tube (pedals to seat) measurements are tricky and can vary from one manufacturer to the other. For example, if you have a 33-inch inseam, you would need a 17.5″ top tube (17.75″ tubes are hard to find)

33″ x .67 = 21.75″

21.75″ – 4″ = 17.75

Specialized mountain bike makers like Lapierre & Neil Pryde have different geometry for their bikes. Multiply your inseam by .62 instead of .67 if you want to get one of these bikes.

Step 3: Perform a Stand-Over Test

Straddle the top tube of the mountain bike with your feet being shoulder-width apart. Grab the stem that connects to the handlebars with one hand and grab the stem that connects to the seat with the other hand. Then pull the frame up against your pelvic bone.

Ask a friend to help you measure the distance between the ground and the wheels. A mountain bike should have 3 to 4 inches (7.6 – 10.2 cm) of space beneath the tires. If it is any more or less, you have to change the frame size.

Step 4: Adjust the Handlebar

The handlebars need to be even with the saddle. For mountain bikers and racers, I even recommend one to two inches lower. The result should be that your elbows should only be slightly bent and your fingers should be light on the handlebars. The position of your handlebars is determined by four different things:

The handlebar angle

To change the handle bar angle first loosen the bolts that connect the stem with the handlebars. Now you should be able to change the angle up or down, depending on what you prefer. You can use this to gain an extra few inches that can influence the comfort significantly.

Handlebar height

Toi changes the handlebar height you can add or remove metal spacers between the frame and the stem. The frist step is to loosen the bolt on the top of the stem and the ones that hold the stem to the frame. Now you can remove the handlebars and add or remove spacers to adjust the height.

However, you can only make minor changes as there is not a lot of room for new spacers. Some older mountain bikes with a quill or threaded stems may allow you to adjust the handlebar height by raising or lowering the stem.

Stem length

Is the distance between the top tube and the handlebars. The longer the stem, the further away the bars will be from your seat. Stems cost $15 to $150 and are the primary way to adjust your frame to make it fit your torso.

Longer stems bend the bike into a more aerodynamic position while shorter stems cause a more upright, calmer riding style.

● Top Tube Length

The top tube length refers to the length of the bar between your handlebar stem and seat post. These are adjusted to fit the frame, and unless you have a very disproportionate body (torso much larger or smaller than legs) getting a properly sized frame will give you a properly sized top-tube.

Step 5. Level your seat angle

Loosen the bolt under the back of the seat to move the seat forward or backward. You have a range of several centimeters. You must make sure the seat is close enough for you to reach the handlebars comfortably. Use a carpenter’s level to make sure the seat is flat, this ensures even distribution of your weight.

Female mountain bikers typically tilt the seat down for comfort. Male mountain bikers typically tilt the seat up for comfort.

What happens if my Mountain Bike does not fit?

You are likely going to suffer from any of 4 different kinds of aches and pains if your mountain bike size is wrong. If you suffer from back pain while riding a mountain bike it is an indicator that the frame size is wrong. You can solve your lower back pain simply by putting the stem up or down by half an inch, or getting a handlebar with more back sweep.

If your shoulders, arms, or neck are hurting, they could be telling you that your mountain bike is either too big or too small. This may be caused by sitting too far forward on the mountain bike or because you’re sitting too far back, making you curl your shoulders and preventing you from holding the bar properly. You will find that more back sweep or upsweep on a bar will make you far more comfortable.

Try to use anatomically shaped grips that support your hands better. If the saddle is too high, too low, tipped too far back or forward, or not offering the right sort of padded support, it will cause a lot of pain in your hips. Knee pain when riding your mountain bike is also caused by your saddle being too high or too low, or because your shoe cleats are not properly adjusted.

You will find that a pedal/cleat system with freer float gets rid of knee pain.

How do I know my mountain bike is the right size?

You must pay attention to the posture of your arms, neck, shoulders, hip bone, and back while riding your mountain bike. If your mountain bike has exactly the right reach for you, its seat tube would be nice and steep, the fork will set up properly, you will probably end up with your saddle set dead center on its rails.

If you have got long arms for your height you may end up with the saddle set well back: If you have short arms, you will be looking at inline seat posts with your saddle forward.

You can use stem length and handlebar position to fine-tune the way you sit over your mountain bike too.

What is the correct mountain bike saddle height?

A rough approximation of maximum saddle height for efficient pedaling is your trouser length measurement plus thirteen cm (5 in) from the center top of your saddle to the center top of your pedal. To work it out more accurately, with comfort and efficiency in mind, you must sit squarely on your saddle with the cranks in a straight-up/straight down position.

Your saddle is at the right height when your heel just touches the top of your lower pedal while your leg is straight. Your crank must be right at the bottom of its stroke. If you have to tilt to one side on your saddle to achieve this position then your saddle is too high. You must place your foot on your pedal in a ready to pedal position.

If your leg is straight while your heel is on the pedal, it should be slightly bent at the knee in a pedaling position. You should never feel as if you are being forced to rock your hips from side to side on the saddle while pedaling.

You may need to make adjustments to this position according to your distance, pace, confidence, and comfort preferences, and what shoes you wear. Keep in mind that this is all done for the sake of efficient pedaling for mountain riding. A slightly tipped-back saddle is good for steep downhill work. Tip the nose of the saddle slightly down for good climbing or a more forward-based ride posture, or if your mountain bike’s seat tube angle is particularly shallow.

A saddle set too far back can make your mountain bike feel too heavy at the back, and possibly too light at the front, especially when you are climbing a mountain. A saddle that is set too close to the front can cramp your ride position and make you feel as though you are putting too much bodyweight on the front of your mountain bike.

Top 10 Bike Fit Calculators Available for Free Online

  1. Amazon Bike Fit Guide: here you will find assistance with 12 different categories: In the main menu you can select mountain bikes for adults. You can also find more products by selecting the frame material, in used or new condition, price range, weight, wheel size, brake type, suspension type, number of gears, featured brands, sellers, sex of the user, and average customer reviews. The guide is free of cost and simple for an average person to understand. You will have to put in your body measurements and the chart will simplify your selection for the accurate size of a mountain bike.
  2. Competitive cyclist fit calculator: This is a free online mountain bike size calculator.
  3. Mountain Bike Frame Height calculator by Bike Exchange: is a general sizing guide. This calculator should be used as a general guide for sizing as many factors go into sizing – including the height of the rider.
  4. Online bike fit by Pedal force: This is also free to use.
  5. Lennard Zinn’s fit calculator: Lennard Zinn is well known throughout the world for designing mountain bikes that truly fit. While a custom Zinn mountain bike is not for everyone, Lennard’s mountain bike fitting methods can help you find a mountain bike that works well for you. You can enjoy this complimentary mountain bike fit calculator.

    There are different calculators for road bikers and mountain bikers. You can click on the appropriate image to get to the right one. You can also enter your measurements to see your ideal mountain bike frame geometry.
  1.  Jenson USA Bike Fit Calculator: This bike fit calculator is quite professional. You should prepare all the information based on their requirements before getting ready to calculate your fitting data. For example, Foot length, arm length, inseam length, and so on.
  2. BIKE FRAME SIZE CALCULATOR by Berg Freunde: First, this site will require your measuring instructions, Secondly it will ask you the type of bike that you want to buy, and then finally it will show you the size chart.
  3. Mountain Bike Size Calculator by E-bicycles: This is the simplest calculator that you would come across online. It will ask you just three simple questions: your sex, your height, and your inseam length. After filling in this data you can push the calculate button and it will show you the frame measurement and the crank size. There is an option to print your data at the bottom of the page if you want.
  4. Bike Fit Guide by Backcountry: This is an app that is free and easy to use. Here you have to select your gender and the type of bike you want to buy and then input your inseam length. It will show you the exact size of the mountain bike.
  5. Bike Size Calculator by Omni Calculator: Here you have to select your gender, bike type, your height in centimeters, your inseam length in centimeters, and the bike frame size in centimeters. Other than this, this site offers 7 more different calculators that are free of cost. They are, cycling wattage calculator, calories burnt biking calculator, bike gear calculator, cycling heart rate zone calculator, like cadence and speed calculator, biking life gain, and cycling breakaway calculator.

How to Ride a Tall Mountain Bike if you are short?

If you are short and you borrow a tall mountain bike from a friend or if 2 different riders, one tall and one short, will share a mountain bike, here are 5 different solutions to help you out.

● Solution 1:

Carry your pair of riding boots to your local cobbler. Ask the cobbler to fix a sole to the already existing one. This will cost you only a couple of dollars most likely $10 but it will bring you a lot closer to the ground. The new sole will give you a lot more grip and control over your ride.

● Solution 2:

Some mountain bikes are compatible with a lower seat that can be bought separately. You will have to cut the original seat and put it on a lower one. To do this, you will need the assistance of a professional bike mechanic. While specifications for the height of mountain bike seats are easily available; specification for the width of the saddle is not.

Seat width has a dramatic effect on your ability to reach the ground. Narrow saddles allow your legs to reach the ground easier than wider ones which push your legs out at an angle making it harder to touch the road. Various third-party mountain bike seat manufacturers offer custom low and high seats for numerous popular brands.  

Professional mountain bike seat manufacturers also offer various types and densities of foam, gel pads, and seat covers. They can lower and narrow your mountain bike seat without sacrificing your comfort and budget.

● Solution 3:

You can customize the handlebar and control placement to fit and give better control. Bar risers can be used to move handlebars upward, downward, forward, and backward to the peculiar preference of the mountain bike rider. You can cut the width of your handlebars to suit your shoulders.

This reduces fatiguing and improves maneuverability in tight areas and uneven terrain. You can use wider, standard-width handlebars on your mountain bike to give you more leverage than a heavier bike.

How to choose a bike size for a kid

  • A two to three years old kid will ride comfortably on a bike with 10″ / 25 cm wheels.
  • A three to five-year-old kid should be gotten a bike with 12″ / 30 cm wheels.
  • A six to eight-year-old kid should be gotten a bike with 16″ / 40 cm wheels.
  • For a nine to an eleven-year-old kid, you should look for a bike with 20″ / 50 cm wheels.

How do I know what size bike is accurate for my kid? Sitting on the saddle of the bike, your kid should be able to rest the balls of his/her feet on the ground. Your kid should also be able to reach the handlebars of the bike with a small bend in his/her elbows and without straining the neck or shoulders.

How is Mountain Bikes different from other kinds of Bikes?

Mountain bikes have a heavy-duty suspension. This means that the rider will not feel a lot of bumps. The high-volume tires of mountain bikes are designed for better control and traction over uneven and rugged surfaces. Mountain bikes have more gears so they offer better control for adapting to the rugged conditions.

Mountain bikes have a lower center of gravity that keeps you balanced riding over roots, rocks, and mud on a track. The center triangle is more compact, with the top tube sometimes angling down, away from the handlebars. Mountain bike frame sizes are usually measured in inches.

Final remarks

To sum up this guide, I would say that by now you should understand the importance of an accurate mountain bike size as it is necessary for the comfort and safety of your own body.

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