Off-road cycling is a great way to exercise, have fun, and connect with nature at the same time. That is to kill three birds with one stone! But to fully enjoy this sport, you need to have a suitable bike. And the very first step to buy the right bike is to know your ideal mountain bike size.
This article includes everything you need to know about mountain bikes, from why you need to choose the right size to the mountain bike size chart and some tips on adjusting the size.
Now let’s get started!
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Mountain Bike Overview
As its name might already suggest, a mountain bike is a bike specialized for off-road cycling. Due to many advanced features such as knobby tires, extra wide handlebars, a suspension fork and so on, it is more durable and able to handle rough terrains.
Unlike the uniform road bikes, mountain bikes are tailor made for different purposes.
For example, some bikes are designed with a generous suspension system to roll over extreme trails. Other models have less suspension to balance support and speed.
To learn more about this mountain bike , please watch this review video:
The Importance of Choosing The Right Mountain Bike Size
Picking a random bike to ride is quick and easy, but it will likely cause severe muscle pains due to insufficient body support. Below are some common pains that people experience when riding on a wrong size mountain bike.
Shoulders/arms/neck: Placing too much stress on these parts of the body can cause acute aches and pains. For example, you need to stretch out to hold the handlebar due to sitting too far back on the bike. In the long run, you will find yourself suffering from a lot of pains in the shoulders, arms and neck.
- Back: Back pain is often caused by poor core muscle support, and it may also imply that you have chosen the wrong frame size. Adjusting the handlebar and the distance from the saddle to the bars can help in this case.
- Knees: Too high or two low saddles are the main causes of knee pains.
- Hips: If your hip aches after riding for a while, it is probably due to the wrong position or poor padded support in the saddle part.
Meanwhile, the right size bike makes every ride comfortable and joyful. You not only feel relaxed but also more balance and control while riding.
Mountain Bike Anatomy
Understanding the overall anatomy of mountain bikes is the first step to choose the right bike size. There are some specific terms that you need to know.
The reach refers to the length between the center of the head tube and the bottom bracket. This is one of the most important measurements in a mountain bike as it indicates how much room you will have when riding, especially when standing up.
If the reach is too long, you will find yourself in an overly upright position, which is certainly not comfortable.
This is the horizontal distance between the rear axle and the center of the bottom bracket. Short chainstay means the rear wheel is closer to the riders, thereby allowing them to maneuver and wheelie with more ease.
Nonetheless, a short chainstay goes hand in hand with a short wheelbase, which plays a role in improving stability while travelling fast and on rough terrains.
Whether you want your chainstay long or short is a matter of preferences. If you prioritize stability, choose long chainstays. For easy wheelies and manuals, opt for a bike with short chainstay.
Seat Tube Length
Seat tube length indicates the distance between the top of the seat tube and the center of the bottom bracket. It affects the position of the saddle, and you can determine the best seat tube length based on how long your legs can stretch comfortably.
Down Tube Length
Down tube length is similar to seat tube length, but it is the center of the bottom of the head tube instead of the top of the seat tube.
Another important figure is the stack height, which is closely related to the bike’s reach. It is the vertical distance between the center of the head tube and the bottom bracket. The stack measurement affects the minimum height of the handlebar.
Good news: stack can be adjusted with handlebar rise and headset spacers.
Bottom Bracket Height
The bottom bracket height, also known as bottom bracket drop, measures the distance between the middle of the cranks to the ground. Mountain bikes with low bottom brackets corner and move from turn to turn well, but they are more likely to hit rocks and roots on the street.
The wheelbase is the length between the center of the front and rear axle. It is affected by a number of factors such as reach and chainstay. Simply put, a long wheelbase will improve the overall stability, while reducing the wheelbase length allows for more maneuverability.
To learn more about this mountain bike anatomy , please watch this review video:
What Size Mountain Bike Do I Need?
Before you scroll down to the buying guide, take a look at the full size chart first. It will save you much time and effort when choosing the right bike for height.
|Rider Height (inches)||Rider Height (cm)||Leg Inseam (inches)||Leg Inseam (cm)||Suggested Frame Size (inches)||Suggested Wheel Size|
|4’10’’ - 5’3’’||147cm - 160cm||25 - 28’’||62 - 70cm||13’’ - 14’’||26’’|
|5’4’’ - 5’7’’||160cm - 170cm||25 - 30’’||63 - 76cm||15’’ - 16’’||26’’|
|5’5’’ - 5’9’’||165cm - 175cm||26 - 31’’||66 - 78cm||16’’ - 17’’||27.5’’|
|5’9’’ - 6’0’’||175cm - 183cm||27 - 32’’||68 - 81cm||17’’ - 18’’||27.5’’|
|6’0’’ - 6’3’’||183cm - 190cm||28 - 33’||71 - 83cm||18’’ - 19’’||29’’|
|6’1’’ - 6’6’’||190 - 200cm||29 - 34’’||73 - 86cm||19’’+||29’’|
What to do if you are in between two sizes, say 5’9’’? What is the suitable frame size for 5’9 and for 5’10? Here are some tips about whether to size up or down when you are on the edge.
When you move from Small to Large, it is likely that the reach increases since most mountain bike brands try to get as low as possible. And since the whole bike becomes longer, the wheelbase length also increases a little. So if you have a long torso, you will want to size up to have a better fit.
Do you have a flexible body? Can you bend over and touch your toes easily? If not, you may find it hard to maintain a low riding position on a long bicycle.
To sum up, sizing up is recommended for anyone who has a flexible body with a long torso.
To learn more about between bike sizes , please watch this review video:
Sizing down offers you a mountain bike with a shorter reach and a slightly shorter wheelbase. Thus, the bike tends to ride more nimbly, as opposed to the aggressive riding positions of long models. You can keep riding for a long time without feeling too tired.
All in all, I would suggest sizing down for anyone who enjoys a casual, nimble ride. Also, those who have a short torso should consider sizing down too.
Bike Size Calculator
This advanced size chart is brilliant, but there is another easy way to know the right bike size for yourself: bike size calculator.
First, take off your shoes and stand with your legs 15 – 20cm apart to measure the leg inseam.
Second, perform a simple math calculation: leg inseam length x 0.685 = your frame size (in centimeters). For example, your leg inseam measures 70cm, then your ideal frame size should be 70 x 0.685 = 47.95cm.
There are formulas for road bikes and city bikes as well:
- Road bikes: leg inseam length x 0.70 = your frame size (in centimeters)
- City bikes: leg inseam length x 0.685 = your frame size (in centimeters)
The Ultimate Guide To Choosing Suitable Mountain Bike Size In 2021
Do you know your suitable mountain bike size now? It is time you read the buying guide for tips and tricks to buy the right bike size.
Ask Your Local Merchant
Some merchants have a clear size chart to consult, some do not, but most of them will be keen to help their customers. Therefore, do not feel shy to ask the local merchant for more information about the size chart.
To learn more about this how to buy a mountain bike , please watch this review video:
Try Before You Buy
All the figures and numbers are not as helpful as the actual feeling you have while on the bike.
Sometimes a recommended size for height cannot give you the control and comfort you desire. That is why you should definitely try riding a bike for at least once before jumping to the final decision.
Several bicycle brands and shops offer demo events when you can test out the bikes, so stay tuned and take advantage of these events.
Invest In a Bike Fit
Getting the right size is important, but getting a bike that can serve your needs is essential. The perfect mountain bicycle not only rides but also allows you to enjoy riding without discomfort, pain, and injury.
Such a bike is not readily available in stores. Instead, you need to get a professional bike fit.
Tips on Adjusting Your Mountain Bike Size
You have bought a mountain bike for adults but it does not offer ultimate comfort. Follow these tips to adjust your bicycle for a perfect fit.
There are many ways to get the right saddle height, including simple formulas and calculations. Here I introduce to you the most simple one – the “heel method”.
Now hop on the bike, start pedaling slowly, and notice your pedaling position.
Do you need to overreach or rock your hips from side to side in order to pedal smoothly?
If yes, the saddle is a bit too high for your leg, and what you need to do is to move your saddle down. In contrast, try going up if your legs bend too much when pedalling.
Keep on trying until you find the ideal pedal height.
Now you need to decide the distance from the handlebar to the saddle.
To figure out the right distance, measure your forearm length, which will indicate the torso and full arm length as well. Place the tip of your elbow on the nose of the saddle and see where the tip of your middle finger is along the stem.
For an efficient trail riding position, the middle finger should be at the middle point of the distance between the handlebar center and the top of the fork steer.
Meanwhile, the saddle height is a matter of personal taste. Some riders like the flat-backed riding posture, so they want their saddle to be way below. Adjust the saddle height based on your comfortable position.
Break and Gear
Like the handlebars, brakes and gear shifters can be put anywhere on the bar depending on your preferences.
Try placing them in some different positions to find out the best spot. I know some riders who use the standard gear shifters for years before realizing that moving them a little further inboard will be more comfortable.
Mountain Bike Fit and Size for Women
The women-specific mountain bikes have been adapted to better fit their body shapes. For example, women’s bikes boast narrower, shorter handlebars in a more compact frame.
Mountain Bike Fit and Size for Kids
Buying a specialized mountain bike for adults and for kids are clearly different, especially in terms of size. The most important thing to keep in mind is that the child must reach the ground to ensure safety while learning to ride. Do not buy a size up for the kid to “grow into” since it is not only uncomfortable but also dangerous for him or her.
For example, 27.5-inch bikes are not suitable for 10 year old kids, unless they are 175cm tall.
The standover height is the first thing to look into. It should be about 2’’ to 4’’ of clearance, regardless of the top tube style.
Also, pay attention to the seat height. Your kids should ride comfortably with their hands gripping the handlebars easily and their legs slightly bent when pedalling.
To learn more about this how to choose a kids mountain bike , please watch this review video:
Frequently Asked Questions
Q: How are mountain bikes sized?
A: Since today’s mountain bikes come in many unique shapes, it is difficult to use the traditional method of measuring the seat tube. Instead, most brands use a Small/Medium/Large system to size their mountain bikes. The size chart also includes frame size, wheel size, geometry number, as well as suspension.
Generally, the only difference between small, medium, and large bikes is the frame size. Of course, there are exceptions when the manufacturers adjust the suspension and wheel size across the size run.
Q: What size of mountain bikes is the best for beginners?
A: Among 26, 27.5 and 29-inch mountain bikes, I would say 29 inches is the best for newbies since they give you more control and roll over rough terrains smoothly. Even if you have little experience riding a mountain bike before, you will still find these 29ers easy to maneuver.
Q: How big is a 29-inch mountain bike?
A: A 29-inch bike is big and tall, which tends to fit people that are 5’6’ and taller. In fact, it offers the perfect riding position for more than 6’ tall riders. 29-inch mountain bikes mostly come in medium, large, and extra-large frame sizes. If you are under 5’6’, you should look elsewhere for a smaller bike.
Q: Can I fix my bike size?
A: It is hard to fix a wrong bike size, but you can try some tricks.
For example, adjust the seat post or the saddle position if the bike is too small. In contrast, sliding your saddle forward or looking for a shorter stem in case you find the bike too big.
Keep in mind that you still need a brand new one if the current bike does not feel right. You need the best suited mountain bike size to cover huge distances.
Q: How much should I spend on my first mountain bike?
A: The exact amount varies depending on many factors, but you should prepare no less than $800 to get a decent bike. At this price range, mountain bikes are robust and can withstand extreme terrains without falling apart.
If you can afford a little extra, take a look at some full suspension models that go up to $1500 – $2000
Q: What age is a 20-inch mountain bike for?
A: 20-inch wheel bikes are designed for kids and teenagers who are at least 8 years old and above. The options in this range are diverse in shapes, sizes, and styles with a lot of features such as gear sets, suspension systems, hand brakes, etc.
The Bottom Line
Choosing the right mountain bike size takes some time and effort, but it is worth all the effort. Think about relaxing and joyful moments when you ride your bike across the mountains. Isn’t it great? Now pick your size and go to the store to try out. I hope you can buy the perfect mountain bike for yourself.
Thank you for reading.