What Size Mountain Bike Do I Need?

An excellent mountain bike fit offers more comfort, better control and goes a long way toward having an enjoyable time on the trails. So it’s essential to understand mountain bike basics from design, frame geometry to the kind of trails you will be riding on most of the time.

Because there are multitudes of models on the market, you will need to compare specs and stats across those models and pick a mountain bike that lines up best with your body measurements, riding style, and budget.

To save you the hassle of going through tons of articles or shops in your locality, this guide will help you get ideas on what size mountain bike you need.

Mountain Bike Sizing

Ask enthusiast bikers about mountain bike fit, and they will tell you the same vibe – all bikes feel, perform and ride differently even when their size or numbers look the same.

Long ago, manufacturers classified mountain bikes based on seat tube length and top tube length, but more recently, they have started listing their brands’ sizes based on reach figures. This means that they have developed the bike’s reach, wheelbase as well as top tube length while trying to keep stack heights and seat tube lengths shorter and lower.

Most manufacturers base their sizes on classic Small, Medium, and Large sizing. All in all, most mountain bikes are sized the same using rider’s body shape and measurements (height, inseam length, etc.) to determine the correct frame size.

In most cases, mountain bike frame size is the only thing that differs when you go between various models and sizes. Other things like overall geometry, suspension, wheel size remain the same. Even so, some manufacturers might change them -suspension and wheel size – across the size of the same model.

Mountain bikes are designed for all kinds of terrain. They usually have sturdy frames, thick tires, and suspension – front suspension or full suspension – for absorbing bumps from rough terrain.

Mountain Bike Size Chart

The best place to begin when trying to determine the correct size mountain bike for you is by studying a size chart. Our mountain bike size chart below is a good baseline to help you get the right fit for your height.

Be sure to look at the brand-specific mountain bike size chart as different brands have varying designs and frame geometry.

 

Rider height (feet & inches)Rider height (cm)Frame size (inches)Frame size (cm)Frame size
 

4′ 10″ – 5′ 2″

 

148 – 158

 

13″ – 14″

 

33 – 37

 

Extra Small

 

5′ 3″ – 5′ 6″

 

159 – 168

 

15″ – 16″

 

38 – 42

 

Small

 

5′ 7″ – 5′ 10″

 

169 – 178

 

17″ – 18″

 

43 – 47

 

Medium

 

5′ 11″ – 6′ 1″

 

179 – 185

 

19″ – 20″

 

48 – 52

 

Large

 

6′ 2″ – 6′ 4″

 

186 – 193

 

21″ – 22″

 

53 – 57

 

Extra Large

 

6′ 4″ +

 

194 +

 

23″ +

 

58 +

Extra Extra Large

 

While mountain bike frame size is a good starting point, there are other key factors such as geometry, skill levels, intended use, etc., to help you pick the right fit.

Mountain Bike Geometry

Mountain bike shape is literally its geometry, which is made up of various and crucial measurements. They help determine the right fit, feel, and style of the bike.

Also, they are proportional to the style together with the terrain your mountain bike was intended to perform on. Essential parts and measurements that affect mountain bike geometry are the Reach, Stack, Head Tube Angle, Seat Tube Length, Bottom Bracket Height, Chainstay Length, and Wheelbase.

The Reach

Reach is the horizontal distance between the center of the head tube and the bottom bracket axle. It dictates how the mountain bike actually fits you. And unlike the saddle height or seat tube length, you can’t adjust the reach.

Reach affects your mountain bike’s cockpit length when you stand on the pedals and how much range of motion in your hips you will use to attain a comfortable and strong riding position.

Too long reach will make you lean over as well as stretch out, while too short reach will shift your weight bias more frequently, which is risky, especially when riding on challenging trails. Here are our recommended reach numbers for particular rider heights.

 

 

Rider height (feet & inches)

 

Rider height (cm)

 

Reach (cm)

 

5′ 2″ – 5′ 6″

 

158 – 168

 

41 – 45

 

5′ 6″ – 5′ 10″

 

168 – 178

 

43 – 47

 

5′ 10″ – 6′ 2″

 

178 – 186

 

45 – 49

 

6′ 2″ – 6′ 6″

 

186 – 198

 

47 – 51

 

The Stack

Stack is the vertical distance between the center of the head tube and the bottom bracket. It affects the handlebar height and rider’s hand position. To achieve effective control while ensuring comfort when riding a mountain bike, you must have the right stack length.

How comfortable you grab the handlebars while seated in pedaling state or on aggressive riding makes all the difference. Luckily, you can adjust the stack using headset spacers along with handlebar rise to achieve a perfect one.

The Head Tube Angle

It’s the angle between the ground and the bike front fork. Head tube angle is the leading factor manufacturers, and riders use to judge the characteristics of the mountain bike front wheel. A little slacker head angle is approximately 65 degrees which offer more stable performance at high speed and makes the riding feel more comfortable, especially on steeper or downhill terrain.

Conversely, your mountain bike will steer lazily as well as flop sideways uphill; thus, you require to change your body position, like keeping the weight of your body on the front wheel to effectively tackle uphill terrain.

On the flip side, mountain bikes with a more steep head angle (70 degrees) allow the rider to go very fast uphill because the front wheel feels planted. On the other hand, it feels twitchy and unstable on downhill terrain.

So, if you ride on downhill terrain most of the time, a slack head angle is the right one. And if your preference is uphill pedaling, go for a steeper head angle.

The Seat Tube Length

It’s the distance from the seat tube to the bottom bracket axle. You must consider adjusting the seat height to ensure a proper fit.

For flat terrain and when climbing hills, ensure that your legs are slightly bent, approximately 80 to 90% of your full leg extension. At this position, you will use your leg muscles to pedal efficiently and powerfully.

For descents or downhill riding, lower your saddle to get a low center of gravity for better control. Despite the situation, be sure to achieve the best saddle height for comfortable riding. Keep in mind that over-tightening the blinder bolt or lever might damage the seat tube – the carbon fiber frame.

Alternatively, you can add a dropper seat post that allows you to raise or lower the saddle with a simple push-button. It makes work easier, especially when constantly changing the terrains.

Also, the seat tube should leave a rider with enough standover gap (the distance between the top tube and the crotch) as well as usable standover clearance.

To achieve this, stand back with legs straight and feet apart while over the mountain bike and make sure there is a few inches allowance between the top tube and your crotch.

The Chainstay Length

Chainstay length is the effective distance from the center of mass of the rider to the rear axle. This distance is personal to every rider, depending on their taste, budget, locality, and other things.

Short chainstay mountain bike has rear wheel more close to being “under” riders. They allow people to be more dynamic with the positioning of their weight when riding. This accounts for easier manuals and wheelies and overall ease of getting their front wheels off the ground. It boils down to general wheelbase length, which is responsible for mountain bike stability at speed and over rough terrain.

Even though short chainstay offers nimble riding, unfortunately, these mountain bikes are not very stable for both uphill and downhill riding. Thus if you prefer more stability, go for mountain bikes with longer chainstays.

The Bottom Bracket Height

It’s the distance from the center of the mountain bike crank to the ground and effectively measures how low a rider’s center of mass is. Mountain bikes with low bottom bracket height corner like they are on rail and transition effortlessly from turn to turn just like sports cars.

Sadly, the earth and trails are not flat or typically paved smooth. The lower the bottom bracket, the high chances of clipping or digging rocks, roots, or logs you are trying to hop over.

Skilled and savvy riders can make sure their pedals are not down when passing over obstacles, but that definitely means not pedaling over rocks or rough terrains. This can be difficult and danger-posing, especially when biking at blinding speeds.

The Wheelbase

Several factors come into play when determining the wheelbase length, including the chainstay length, the head tube angle, and the reach. Total wheelbase length largely depends on these factors.

The gist of the mountain bike wheelbase is that shortening the distance between the front axle and rear axle will increase the bike’s maneuverability. On the other hand, increasing this distance (wheelbase) will increase stability.

In-Between Sizing

So you have matched your measurements, including height and inseam, to the manufacturer’s mountain bike size chart, and you are on the edge of a size or in-between sizes – what next? Here is how to size up or size down when you are in-between mountain bike sizes.

Sizing Up

When it comes to sizing up mountain bikes, the reach tends to change more from Small, Medium, to Large than the stack. Nowadays, manufacturers are trying to modify the reach to match a perfect spot of the rider’s range of motion when biking.

If you have a long torso and quite flexible, you require to size up the mountain bike to get a neutral fit. Sizing up will also increase the reach proportionally.

Sizing Down

Similarly, a mountain bike having a smaller frame size will both have a shorter reach and wheelbase. Such bikes will also offer a low standover clearance, which may need you to extend the length of the seat post to get a proper pedaling position. But it’s worth considering if you are in-between sizes.

So, if you have relatively long legs and lack flexibility or like to be more upright, a shorter frame can be more comfortable for your riding.  A shorter frame size with a relatively short wheelbase will allow you to pedal faster, which is excellent when you intend to ride the mountain bike for a longer time.

Components Affecting Comfort and Control

Tires

Tire compounds, base, and pressure will influence how a mountain bike feels and “behaves” on the trails. High threads per inch (TPI) tire carcass will deform more over rocky or rough terrain, thus offering better grip without the increase of rolling resistance.

Inexpensive mountain bike tires grip less and have high chances of losing traction when under pressure, mainly in wet trails.

Handlebar Grips

The best grips get to contact points right so that a rider can increase confidence and more control while decreasing arm pump. The most common design is the lock-on design that stays in place and has one or two end-clamps.

Slipping off the handlebars on bumpy terrain or losing the grip can result in serious damage to your bike, including your body.

Sticky or soft compound grips with well-placed contact points may not be hardwearing, but they are more comfortable when it comes to absorbing vibration. Also, a ride feels at ease on the mountain bike on rough terrain.

Saddle

Mountain bike saddles come in various sizes and designs to accommodate different body shapes. Getting the right one for your body has to do with the saddle width and how well it supports your sit bones (ischial tuberosities). You want a wide enough saddle for good support, but not so broad that it brings about rubbing and chafing.

The right padding material on a saddle can make a huge difference to how a rider feels about their bikes. As a rule, a rider should feel at ease and move freely on the saddle’s surface because uncomfortable ones can cause pain in the backside. Essentially, slimline saddles that have minimal padding distributed evenly are more comfortable than big bouncy ones.

Be sure to try a few saddles, as some manufacturers actually offer dealers with demo saddles. Ensure that the mountain bike shop you prefer recommends the right saddle for you or offers some for demo. Otherwise, try other bikes, even if it will be in a different shop.

Pedals

The efficiency of mountain bike pedals/shoes significantly impacts how you ride and control your bike. Consider stiff-soled shoes that have inset cleats fixed to clipless pedals because they will make you a more efficient and powerful “full circles” pedaler. You better read and understand the instructions carefully when it comes to cleat positioning because poorly positioned ones can result in issues, mainly with kneels.

Even though most riders start with their cleats placed dead center in their shoe recess, it doesn’t feel suitable for everyone. Also, some pedals/cleats provide more free float movement compared to others. Just get the right pedals or shoes for comfy, enjoyable, and safe riding.

Suspension and Tire Pressure

Tires, suspension fork as well as rear shock effectively offer an adjustable cushion between your mountain bike and the ground. Therefore, setting them up properly is important to ensure comfort and total control.

Big volume tires can effectively operate at lower pressures than smaller volume tires. Plus, big volume tires having a low knob profile will usually roll as fast as, and provide more comfort together with control than skinny tires.

Tire pressure must be adjusted to suit your riding style, the tires’ width fitted to your mountain bike, the rims’ the tires are seated on, and the trail type or conditions you are riding on.

However, if the mountain bike seems to ping around on a trail and you have confirmed your suspension is correctly set up, then the tires may be too hard. Equally, if your tires seem to squirm or roll on the rim in turns, then know that they are too soft.

Various mountain bike makes and models have different fork and shock settings, so make sure that you refer to a brand-specific suspension setup guide to know how to dial in the right suspension.

Hands-On Bike Fitter Help

You might feel overwhelmed or frustrated after reading this mountain bike guide, but fear not! A reputable mountain bike shop or bike fitter can significantly help you to get the right size for your unique needs.

Some bike shops even offer bike fitting sessions to help you nail down what size mountain bike you want as well as how you can modify it to fit you better.

The Bigger Picture

The right mountain bike size should offer you enjoyable, comfortable, and controlled rides every time. Here are some tips to gauge the performance of your bike:

  • Arms: Optimally performing mountain bike results in quite relaxed shoulders together with slightly bent elbows
  • Frame: Getting the correct frame size is vital, but it’s just the starting point for a proper mountain bike set up
  • Saddle: A proper saddle position is very important for balance, total control, and pedaling efficiency
  • Knees: At the bottom of every pedal stroke, it’s perfect when you have slightly bent knees

Conclusion

That is enough information to help you get the right size mountain bike. That said, the right bike fits and feels right to you despite other people’s opinions and recommendations. So let this information guide you throughout the process, and don’t forget to throw your leg over as many mountain bikes as you can until you get the perfect fit.

There is nothing more satisfying than riding a mountain bike that fits you perfectly. Such a ride becomes part of your body, so it’s worth spending your time, effort, and money to get the best. Success in finding your next mountain bike.