Whether you’ve never ridden a bike before or you haven’t done it in years, getting a new bike is always difficult since you have no idea how to figure out that mountain bike frame size chart and ensure that you’re getting the right one for your size. While the basic measurements are the rider height and the leg height, there are more things to consider before choosing.
So read on and understand how to get the perfect mountain bike for your needs.
A bit about manufacturers and sizing
The only thing people seem to agree with nowadays when it comes to bike sizes and mountain bike sizes is that they’re really all over the place. Some manufacturers overstretch (or overstate) the sizing while others are stuck in medieval times, so you get so many sizes for frames that it’s really tough to choose.
But there are some basic rules you should follow when it comes to your bike’s frame size. Before we go into details here, you should first know that there’s no right or wrong answer when it comes to immediate sizes, as an M or an L frame could work just as well for you depending on how you’re going to ride it and what components you will put on it.
You can go for a longer stem, move the saddle a bit forward, lower the seat post, change components and optimize your ride so the actual frame size won’t count as much unless you’ve got it terribly wrong, such as ordering an XL frame when you really should have gone for the S. But one size difference isn’t much difference at all if you know how to customize your ride.
Mountain bike frame size charts
Most manufacturers will have some sort of frame size chart where the usual measurements are the total rider height and the inside leg height. The simplest have the rider height and depending on the manufacturer, you might see different measurements.
For example, you could see the S size corresponding to a 15″ – 16″ frame and have it recommended for people with a height of 5′ 3″ – 5′ 6″, with the XL size corresponding to a 21″ – 22″ frame that’s fit for people that are 6′ 2″ – 6′ 4″ high.
What’s good to know is that every manufacturer has its own size chart so you should take all these with a grain of salt. A good idea might be to look at what previous customers had to say about a particular model in online reviews as you might figure out whether a specific size is good for specific rider sizes or not.
If all else fails, you can also join a dedicated MTB community and ask there for the opinion of seasoned riders, they’d be more than happy to share their knowledge and give you advice regarding which size might suit you.
Mountain bike frame sizes relative to wheel sizes
Now that you know a bit about frame sizes, you should also learn a bit about wheel sizes. Why is this important? That’s because most frames only accept one wheel size, so if you get a 26-inch frame, you’re going to be able to fit only 26-inch wheels.
The main wheel sizes are 25”, 27.5”, and 29” or 29ers. You also get 27.5+ 29+ but we’ll stick to the three main ones.
26” is the old standard and not many manufacturers are making new models with this wheel size. The advantage of these wheels is that, since they’re small, they offer better maneuverability which is important for things such as forest trail riding where you need to take quick and sharp turns, perform jumps, etc. Needless to say, 26” bikes are great for kids or for small people.
The 29ers are the largest standard (or at least until 29+ came along) and they’re great for speed. Since the wheels are so large, pedaling efficiency is much higher than with any other size. These are fit for those who love speed on fast descents but don’t care that much about maneuverability since you lose quite a bit of it when opting for large wheels. That’s the compromise you make. 29ers are also fit for large people, for obvious reasons.
Now in between these two sizes, we have the 27.5”. These are the sweet spot, as they’re faster than 26” but they still retain great control capabilities as opposed to 29ers. Many people opt for 27.5” bikes since they aren’t too big, nor too small, and they give the right mix that makes them suited to races and all sorts of riding.
Pure downhill riders might want to go with 29ers, but they will have to sacrifice cornering capability which is not something many are willing to sacrifice, and we agree with them. After all, nobody can actually descent in a straight line on rough terrain, and on steep inclines, going down fast is going to be inevitable no matter what you do. What’s important is that you still get to control the bike properly.
In between sizes: do you go one size up or one size down?
That depends on your riding style and on what you’re going to do with the bike. There are a few magazines that did some tests and it appears that the riders who chose to go one size down and enjoy their rides more were the ones who loved forest/off-road trails.
The smaller frame sizes allowed them to be more playful, be more aggressive when cornering or making jumps, and it gave them more control over quick maneuvers.
The riders who preferred to go one size up were the ones who loved speed and valued pedaling efficiency more than maneuvering capability. A larger bike allows for more room to stretch and adopt a good position for flat riding as well as for climbing steep hills.
So there you have it: if you love being playful and riding all sorts of forest trails while performing tricks if you value control, then you can go one size down. If you’re a speed addict, a larger frame might work better for you.
Problems from getting the wrong size
Now, just as mentioned in the article, if you get a frame that’s just one size up or down, things aren’t really that bad and you can easily customize the ride to perfectly suit your preferred position and riding style.
However, if you get the frame size terribly wrong, then you can expect some problems, ranging from minor to quite annoying.
The bike’s too big
If you get a frame that’s too big, you can be almost certain that you’ll have a sore back every time you spend a few hours on the bike. That’s because you’re overreaching for the handlebars and straining those back muscles. The reach is the horizontal distance between the bottom bracket and the center of the head tube, and it’s supposed to allow you to keep your hands somewhat relaxed when in a riding position.
A bike that’s too large also puts you at risk of some painful experiences if you have to brake suddenly and end up with some sensitive parts on the top tube. The idea is that the standover height must allow you to stand with your feet on the ground with enough clearance between your crotch and top tube unless you really love pain.
Now, if reach can be adjusted by getting a shorter stem, a shorter handlebar or by moving the saddle in front, the clearance can’t really be modified unless you change the wheels to a smaller diameter, which is a thing that you can’t do in most situations since most frames accept only one wheel size.
A bike that’s too big will also give you poor control so you will have a hard time making tight turns or sometimes even controlling the bike properly.
The bike’s too small
If the bike is too small, you will surely get pain in all the wrong places due to the fact that you will be riding in a cramped position for a long time (actually, always). If pain is something you may be able to tolerate, there’s also an increased risk of injury, so you might want to change the bike if it’s too small.
You might also have toe overlap problems, and, on long rides and descents, back problems from too much standover clearance.
The best advice is to get the right frame size, if it’s just one size lower/higher it shouldn’t be a problem, and, if you get a chance to try it before you buy it, that would be preferred.
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