Full Suspension Carbon MTB Frame MFM100 is one of our best mountain bike frames, it is also a 21-inch frame mountain bike, the main thing is that it is a trail frameset; it is equipped with a Trunnion rear shock frame, internal alignment design, we deliberately offset the position of the rear shock, so that the structure of the bike can be smooth.

MFM is available in four sizes: S/M/L/XL.
Bad news: mountain bike frame size is all over the place. There is no consistency. One brand’s Medium/17in bike is another brand’s Large/19in. What’s more, a lot of bike manufacturers’ – and even bike shops’ – sizing advice is often wrong too.
Ultimately you do not have a foolproof frame size. Not one that tallies with what bike brands say, nor one that is consistent from bike to bike. This means shopping for a bike is not simple, particularly if browsing online beforehand. It is not a good idea to select just one frame size and filter the results by that; select the frame size the brand recommends and also the size above.
Wondering how to pick the right size mountain bike? Read along and we’ll walk you through the process. For riders coming from another cycling background, it’s important to note that mountain bike sizing is significantly different than road bikes, and other kinds of bikes. If you are interested in learning more about today’s spectrum of mountain bikes, and what to consider when making a purchase, check out our mountain bike buyer’s guide!
The best place to start when trying to choose the right size mountain bike is by looking at a size chart. Our bike size chart here is a good baseline, helping you find the right size bike for your height. We also recommend looking at the size chart that is specific to the brand you are looking at due to differences in design philosophy and geometry. On each of our mountain bike product pages, we have the size chart for that brand. While the size of the bike frame is a good starting point, there are other factors, like geometry, intended use, and skill level that factor in to choose the right size bike – we’ll cover these below.

How Are Mountain Bikes Sized?
Most mountain bike manufacturers use classic Small, Medium, Large sizing. For the most part, bike frame size is the only thing that changes when you go between sizes – things like wheel size, suspension, and relative geometry number remain the same. However, some manufacturers will change things like wheel size and suspension travel across the size run of the same model.
Seat tube length is the traditional method for bike sizing, but with all the interesting shapes that mountain bikes come in these days, it has become less relevant to finding what size mountain bike you should get. Most mountain bikes focus on an extremely low standover height, so the traditional method of standing over the bike flat-footed doesn’t really work either. This is why mountain bike manufacturers use Small, Medium, Large sizing and give their own size recommendations based roughly on your height.
Sizing Up Or Sizing Down Your Mountain Bike
So you’ve matched your height to a manufacturers mountain bike size chart, and you’re right on the edge – what do you do now? Sometimes you’re in between mountain bike sizes. Here’s a few tips on when to size up or size down your mountain bike when you’re in between sizes.
What You Get for Sizing Up
When it comes to mountain bike sizing, Reach tends to be what changes more from Small to Large than Stack. Almost all mountain bikes are trying to get as low as possible to buy the rider range of motion in the cockpit of the bike so you’ll see a lot of bikes with an increase in Reach. There’s also a minor corresponding increase in Wheelbase as the whole bike itself gets a little bit longer, so you get the benefits (and pitfalls) of a longer mountain bike. Also, if you happen to have a proportionally longer torso, you’ll want to size up in order to get a neutral fit, since Reach is primarily what’s affected by the size. Flexibility and range of motion in your hips is also something to consider. If bending over and touching your toes sounds like a tall order, a longer bike is going to be a bit more taxing to maintain a low and aggressive riding position. On the other hand, if you know the difference between your Tadasana Pose and your Lotus Pose (AKA: you’re a supple yoga leopard), a larger size will reward you with a more aggressive riding position.
To sum up: If you’re flexible, longer in the torso and like to monster-truck over your terrain rather than whip or flick your way around it, size up your mountain bike.
What You Get for Sizing Down
Conversely, a smaller sized mountain bike will have a shorter Reach and a slightly shorter Wheelbase. Stand-over height will be a tad lower and you might have to extend your seat-post a bit in order to get to your pedaling position, but it’s a pretty minor consideration when it comes to being between sizes. If you’ve got proportionally longer legs than average, lack a bit of flexibility or generally like to be more upright , you may be a bit more comfortable on a shorter size. Additionally, a shorter Wheelbase will ride more nimbly and while the longer cockpit provides a really aggressive riding position, low and aggressive riding positions are tiring to be in, so consider your fitness, endurance and ride length. Shorter bikes are easier to be on for long periods of time.
To sum up: If you like a more nimble and whippy ride, are a bit less flexible, are shorter in the torso or are looking for a more casual riding position, size down your mountain bike.
If you want to know more about xl frame mountain bike, feel free to visit our official website: https://www.trifoxbike.com/.