Even for people in urban areas, mountain biking has grown in popularity recently. Mountain bikes offer a thrilling way to explore nearby natural areas, without devoting a lot of space or funds to equipment. If you want to give this beloved sport a try, though, you should learn how to size a mountain bike.
Having a properly-sized bike allows you to explore the trails safely, and lets you enjoy the experience much more. When your bike fits properly, you can ride comfortably for surprisingly long periods of time. On a bike of the wrong size, you’re more prone to accidents and injury.
Ready to learn how to size a mountain bike? Whether you’re just getting started, or you have an old bike that no longer feels comfortable, here’s what you need to know.
Why Mountain Bike Sizing Matters
It’s easy to shrug off the importance of bike size. Even experienced riders do it. However, there are a number of reasons why your bike size can make a huge difference.
Here’s why you should learn how to size a mountain bike properly, no matter how long you’ve been riding.
A correctly-sized bike will keep you comfortable because the size of a bike affects the position of your body when you ride it.
When you ride on a bike of the wrong size, you’re typically forced into bad posture. Posture matters for any ride, whether you’re going for speed, stamina, or another goal. With improper posture, you’ll soon start to feel pain in your lower back.
The more you ride, the worse the pain will get.
Even though bikes allow you to adjust the seat and handlebars, you can’t adjust the frame. And an incorrectly-sized frame will almost always lead to back pain in time.
Your wrists will probably start to pick up the slack of your bad posture. So, in addition to back pain, you’ll eventually start to feel wrist pain, too.
With a too-small frame, you’ll end up taking a position that puts undue pressure on your wrists. And with a too-big frame, you’ll over-stretch your wrists as you reach for the handlebars to maintain control.
In addition to causing pain in various body parts, a bike of the wrong size can also sap your energy. And anyone who’s ever been mountain biking knows that you need as much energy as you can get.
When you don’t ride a properly sized bike, you lose a lot of efficiency in pedaling. You won’t have the correct leg position to pedal easily without straining. That burns up your energy, leaving you fatigued much faster.
Safety makes the most important reason to learn how to size a mountain bike.When you ride an incorrectly-sized bike, you don’t have maximum control.
That leads to an increased crash risk, putting you in needless danger. You’re especially likely to lose control if you have a bike with a frame that’s too big.
If you’re between sizes, it’s often best to choose the smaller size, which gives you a bit more control.
Mountain Bike Sizing Terms To Know
As you start shopping for bikes, you’ll encounter some terms you may not know yet. It’s helpful to learn the vocabulary, especially if you’re new to mountain biking. With time and this knowledge, you can even get a good idea of what size bike to buy without actually trying it in person.
While the frame size seems like the most important measurement, it’s actually just the start of knowing how to size a mountain bike properly.Frame sizes often get measured in inches. Most mountain bike manufacturers offer charts to help you see which frame size will correspond best to your height and body type.
However, different manufacturers use different frame size measurements, which can make things confusing. Traditionally, the frame size measures the length of the seat tube. But even that measurement can change, depending on whether the manufacturer measures from the top or the middle of the seat tube.
Other manufacturers may list sizes of small, medium, or large, which can make bike-shopping feel just as vague as shopping for clothes. Just like with clothes, you’ll typically get the best results from “trying on” a bike in person.
Since mountain bikes have wide variations in design and style, even two bikes with the exact same measurements can fit differently. So, while knowing how to size a mountain bike is important, you should usually try out bikes yourself to find out what really fits best
The standover height refers to the height of the frame in relation to your inseam. Seat tube length affects the standover height of a bike.As the name suggests, you’ll stand over the bike to get the standover height. Or, you can simply compare your inseam measurement to the height of the bike frame.
However, calculating the standover height accurately can get difficult, because the shape of the bike frame also plays a role. The true standover height should get measured from the middle of the bike’s top tube or effective top tube (more on that below).
For a mountain bike, look for a standover height of about two inches. Three inches can work well, too. Road bikes, on the other hand, can have standover heights of just one inch.
Since the frame shape can affect the height, you’ll want to take this measurement in person. Stand over the middle of the frame, and make sure your feet are flat and even on the floor.
Put on the shoes you plan to wear while riding before you take the measurement. Then, measure the distance between your inseam and the top of the bike frame.
Effective top tube
The bike’s “effective top tube” measures the distance from the seat post to the center of the head tube. The actual top tube may be slanted, but the effective top tube will be more horizontal.
Measuring the effective top tube distance will help you know how far you’ll have to reach for the handlebars, which influences fit and control. The angle of the seat tube and the height of the saddle will also affect this measurement.
The stack measurement measures the vertical distance between the effective top tube and the bottom bracket’s center. This measurement will influence the height of the handlebars, and the hand position you’ll need as a result.
The proper stack height can give you proper control while minimizing wrist pain. However, the stack height isn’t static. You can change it by raising the handlebar or adding headset spacers.
Reach starts from the point where the center of the bottom bracket meets the effective top tube and measures the distance from there to the center of the head tube. The term "reach" refers to the distance you’ll have to reach to grab the handlebars when you’re standing (as opposed to sitting in the seat).
On a mountain bike, you tend to spend more time standing than sitting, so reach is an important measurement. Although you should also measure the effective top tube, the reach will give you a better idea of how much control you’ll have.
Saddle height refers to the height of a bike seat. You can adjust this height to put yourself in the proper stance, so you maximize pedal efficiency and control.
Check the standover height
First, check the standover height, as described above. If you don’t have a tape measure, just use your fingers. There should be about two to three finger-widths between your inseam and the top tube.
Now, try sitting on the seat. You should be able to just barely touch the ground with your toes. If you can only touch one side of the ground at a time, that’s fine too.You might need to adjust the seat height to achieve this.
Make sure your feet also reach the pedals comfortably, without quite fully extending your legs when you’re sitting down. Reach for the handlebars, too. You should be able to grab them without stretching too far, or hunching your back over.
Take a demo ride
Many bike sellers will let you take a demo ride before you commit, which can really show you how you’ll feel on the bike. Even the best mountain bikes under $$ are worth a test ride first.
Although all the measurements might have seemed right, you can discover fit issues during a demo ride, so this is an important part of how to size a mountain bike.
Take a few bikes for demos so you can see how they all feel different before you commit to one.
Once you find a frame that feels right, you’ll likely need to make a few adjustments, such as changing the seat or handlebar height. That helps take the fit of your bike from good to perfect.
Ready To Enjoy A Well-Fitted Mountain Bike?
Knowing how to size a mountain bike can make all the difference in how much you enjoy the sport. If you’ve tried mountain biking before and found it uncomfortable, you were probably on a bike of the wrong size.
This guide will get you started with all the basics of shopping for the right-sized bike. Now, you’re ready to find a bike that will let you explore the trails safely and comfortably.
Where will you take your mountain bike first? Let us know which trails you’re dying to try in the comments!