One very popular topic that’s always asked about online is mountain bike sizing. But here’s the funny part – you need to get off the internet and spend some quality time with some real mountain bikes to learn about sizing them!

But since it is so important to get it right (your comfort and safety depend on it,) I’m going to give you some tips to point you in the right direction. So let’s get started right now!

 

Mountain Bike vs Road Bike Sizing

(Feel free to skip this section if you have no interest in road bikes.)

In case you are used to sizing road bikes, I must warn you – sizing a mountain bike is different.

With road bikes, you get technical and take very precise measurements to dial in the correct frame size and riding position. With mountain bikes, the process is a lot more laid back. That’s because of the nature of mountain biking – you encounter so many different scenarios and move around on the bike so much, it would actually be counterproductive to have such a precisely fitted bike!

Here, it’s not about the perfect fit. It’s about a good fit and accommodating the special needs of mountain biking that you don’t have to deal with on the road.

The point is, don’t fret if a bike shop employee takes a laid back approach to sizing your mountain bike.

 

How Mountain Bikes are Sized

When looking at mountain bike sizes, you will first be presented with the frame sizes. The frame size is so important that bikes are labeled just by this size.

Frame size is based on the frame’s seat tube length. It is generally measured from the center of the bottom bracket shell to the center of the top tube, where the top tube bisects the seat tube. The measurement is stated in inches, so you’ll find frames sized 15″, 17″, 18″, 19″, etc.

There are two ways companies state bike sizes, though. The first is in inches, as mentioned above, but what is becoming quite common today is labeling bikes Small, Medium, and Large, etc.

What are we forgetting? Top tube length!

Equally as important to the seat tube length is the top tube length. This will vary based on the seat tube length, manufacturer, and style of bike.

Generally, the XC race-oriented bikes have longer top tubes than recreational or all-mountain bikes, but all brands of bikes will vary in this regard. You might try a size medium Giant and a medium Specialized, and guess what? Their positions will feel different!

Does any of that matter? Not really!

Seriously, don’t get bogged down with any specific numbers. I’m not going to give you any sort of chart that plots your correct bike size based on your height or inseam because they just don’t work. (I already went on a rant about choosing a frame size, so I don’t need to do it again.)

There’s not a lot you can do here except test ride the bike and see how it works!

Then test ride another one and see if it is better or worse!

 

Do Your Height and Inseam Length Matter?

There’s a lot of garbage information online about bike sizing, and that leads people to believe they can purchase a bicycle based on their height and/or inseam length.

Sorry, it’s not that simple!

You have to take into account your height, inseam, arm length, torso length, flexibility, riding style, and a myriad of other factors when choosing a mountain bike. So if I told you that you need size X bike since you are Y height, I would be doing you a grave disservice!

So yeah, your height and inseam do play a role, but you have to take your individual body into account. Everyone has different proportions (short but with a long inseam, for example,) and this means everyone will have slightly different requirements for sizing.

I’ll say it again – you need to fit the bike in real life to be sure it fits. Don’t just rely on a chart. And – test ride before purchase!

 

Sizing The Bike for You

I don’t want you to blindly go bike shopping, since some shops aren’t the smartest at proper sizing, so I’ll give you some tips to make sure a bike is the correct size for you.

This is still generalized advice for when you sit on a bike, though, so take it with a grain of salt.

Standover clearance

When standing over the bike, straddling the top tube, you’ll want at least 3-4″ of clearance at your groin. This should be self explanatory for any guys!

Seat height

To get a quick, rough estimate of your proper seat height, sit on the bike and place your heel on the pedal (with the pedal at the 6 o’clock position.) Raise the seat to where your leg is straight in this position.

This should put you in a position where your knee is slightly bent at the bottom of the pedal stroke (assuming proper foot placement) and your hips don’t rock side to side when you pedal.

Keep in mind, you also want the saddle low enough you can get your butt way back behind the seat for steep downhills. So this isn’t a conclusive test for your exact seat height. It’s just to see if the bike is potentially going to fit you.

Reach

If the bike passes the standover and seat height tests, now it’s time to make sure you have a comfortable reach to the handlebar.

For this, just sit on the bike and hold the handlebars, and see if you’re comfortable. The bike shop employees will see if you’re too crunched up or too stretched out.

Toe overlap

Common on some road and cyclocross racing bikes, toe overlap is something you do not want on a mountain bike! So just do a quick check where you twist the handlebar side to side and make sure the front wheel does not hit your front toe when you’re in the riding position.

 

In Between Sizes?

What if you’re in between sizes? Or maybe two different size bikes can be made to fit you?

This happens all the time with mountain bikes. Especially with the variety of seatpost and stem lengths. The general school of thought is that you should get the smallest frame that still allows a proper fit.

The smaller frame means three things:

1. The frame is lighter (so a lighter bike overall.)
2. The frame is stiffer for better performance.
3. More standover clearance for safety of the family jewels.

Assuming the smaller bike fits you just fine, and feels just as comfortable and responsive as the larger bike, go for it.

 

Choosing a Wheel Size

Choosing a wheel size used to be a no-brainer – almost exclusively (some kids bikes came with 24″ wheels,) you’d get 26″ wheels on a mountain bike.

Nowadays, there’s a legitimate case for 26″ or 29″ wheels, or even 650b (which is right in between the other two sizes at 27.5″.) There are even “69er” style bikes with a 29″ wheel up front and a 26″ in the rear!

Why go bigger than 26?

The bigger the wheel, the easier it rolls over obstacles. This makes 29ers very fast on rough terrain and gives them a bit of a full-suspension feel, without needing rear suspension.

However, the bigger wheels can take longer to accelerate and be harder to maneuver, so they aren’t well-suited to tight, twisty courses with lots of speed changes. So for this sizing question, you are mainly considering the type of riding you plan to do.

[Usually, 29ers start in a Medium frame size, so if you're on the shorter side, you might not be a candidate for 29" wheels anyway.]

 

Miscellaneous

Sizing your bike is what matters, but there are a few parts sizing guidelines I want to mention in this little miscellaneous section.

Crank arm length

The standard crank arm length for mountain biking is 175mm.

170mm cranks are common on road bikes, but when mountain biking, riders usually prefer the extra leverage gained from a slightly longer crank arm.

Stem length

Stem lengths typically range from 90-120mm, with shorter stems like 90-100mm being the most common.

Changing the stem on a stock bike setup is common and very helpful, since it’s a quick way to change the “reach” to the handlebar.

Handlebar width

Handlebar width typically matches shoulder width, although it is personal preference more than anything.

Keep in mind a wider handlebar can offer better control, but is harder to squeeze between trees on tight singletrack.

 

Custom Built Frames

This is not common, but if you are NBA player tall, or your body has some very odd proportions, it can be hard to set up a normal bike to fit you well.

If this is the case, you might need to order a custom built frame from a small builder or a company such as IF.

If you go this route, you’ll fill out some forms with all your body measurements and be interviewed about your riding style and goals. It will take quite a bit of effort, and it won’t be cheap, but there is always a way to get the right size of bike!

 

Mountain Bike Sizing Summary

Getting the correct size bike is very important. The frame is the most expensive and hardest to replace part of your bicycle. so get the sizing right the first time!

Take your time and do it right. That means talking to shop employees for advice, asking “why” they recommend something, and above all, test riding multiple bikes before making a final decision.

Good luck!

With today’s mountain bikes, you have about a 50/50 chance of getting a twist shift or a trigger shift mechanism. And another 50/50 chance if it will be Shimano or SRAM.

In this article, I will explain how to shift SRAM Trigger shifters.

(Note: If you are looking to learn about the concept of shifting gears, read my Beginner’s Guide to Shifting Gears first.)

 

SRAM Trigger Shifters – The Basics

SRAM Trigger shifters are slightly different than Shimano RapidFire triggers.

With SRAM, you still have two little levers for each hand, but each one is operated by a push from your thumb. This way your index finger can be used for grabbing the bar or brake lever. Your thumb can stay wrapped around the bar for control and still operate both triggers.

I personally prefer this trigger design over the Shimano.

The general shifting method is as follows:

Push the little top lever for a shift to smaller cog or chainring. Push the bigger bottom lever to shift to a bigger cog or chainring.

To learn the details of the shifts, continue reading…

 

SRAM Trigger Shifters – Right Shifter, Rear Derailleur

The right shifter (the one operated by your right hand) will operate the rear derailleur, moving the chain across the 8-10 cogs on the rear cassette.

To shift to a harder gear:

Pushing the upper, smaller trigger will drop the chain down to a smaller cog, putting you in a bigger gear.

To shift to an easier gear:

Pushing the lower, bigger trigger will push the chain up to a bigger cog, putting you in a smaller gear (this will make it easier to pedal.)

 

SRAM Trigger Shifters – Left Shifter, Front Derailleur

The left shifter (the one operated by your left hand) operates the front derailleur. It will move the chain between the two or three front chainrings.

To shift to a harder gear:

Pushing the lower, bigger trigger will push the chain up to a bigger chainring, putting you in a bigger gear.

This shift requires a bit more force than the others, but not a whole lot.

To shift to an easier gear:

Pushing the upper, smaller trigger will drop the chain down to a smaller chainring. This will make it easier to pedal.

 

Trigger shifters may sound more complicated than SRAM’s Grip Shift, but once you practice with them a little bit, you’ll have it memorized in no time!

Mountain bikes are typically equipped with either a grip shift or trigger shifters. The trigger shifters look more intimidating, but they are fun and easy to use once you get the hang of them.

Most likely, if your bike came with trigger shifters, they will be Shimano RapidFire Trigger shifters.

(For advice on shifting concepts in general, read my Beginner’s Guide to Shifting Gears.)

This article will explain how to use these Shimano RapidFire triggers…

 

Shimano RapidFire Shifting Basic Concepts

These shifters are very common on mountain bikes. In this case, you’ll have two small “triggers” beside each handlebar grip. There are two triggers on each shifter because the triggers only move in one direction.

The top trigger is in front of the handlebar, and it is operated by your index finger. The lower trigger (which is a little bigger) sits behind the handlebar and is operated by your thumb. The top trigger is pulled back towards you to shift; the bottom trigger is pushed forward to shift.

Pushing with your thumb will execute a shift to a larger cog or chainring. A quick pull with your index finger will shift to a smaller chainring or cog.

The complicated thing is, this could shift to an easier or a harder gear. It’s different on both shifters, so I’ll explain both sides…

 

Shimano RapidFire Shifting – Right Shifter, Rear Derailleur

The right shifter (the one operated by your right hand) operates the rear derailleur, moving the chain between the eight or nine cogs on the cassette.

To shift to a harder gear:

Pulling the smaller trigger in with your index finger will drop the chain down to a smaller cog.

To shift to an easier gear:

Pushing the bigger trigger with your thumb will push the chain up to a bigger cog.

 

Shimano RapidFire Shifting – Left Shifter, Front Derailleur

The left shifter (the one operated by your left hand) operates the front derailleur. It will move the chain between the three front chainrings.

To shift to a harder gear:

Pushing the bigger trigger with your thumb will push the chain up to a bigger chainring.

To shift to an easier gear:

Pulling the front trigger back with your index finger will drop the chain down to a smaller chainring.

 

Trigger shifters may sound complicated compared to the Grip Shift, but they aren’t a problem once you practice with them a little bit. Go practice shifting and you’ll have it memorized in no time!

[Notice: SRAM Trigger Shifters operate differently than Shimano RapidFire.]

Today’s question is about why you might be blowing up when hitting a tough hill climb, even if it didn’t happen last season…

okay man, quick question. i have been MTBing for around 4 years now. recently came home from school, felt really good off the bat and got into some 14-20 mph rides. yesterday and the day before, i feel a tad weak and i feel like the lactic acid just hits me up right when i hit the climb, this has never happened before.

what do you think it is? i really appreciate all the info you have on this site and if you could answer this question id appreciate that even more. thanks Levi, your the man!

Sincerely,
Blowingup Bob

Hi Bob,

Perhaps you’ve been away at school and not riding quite enough during the Spring semester. Then you come home and jump into things like previous summers, riding like you didn’t take any time off over the past months. You have a good enough base after four years of training that you can do it for a little while without feeling like you’re overtraining, but it’s starting to hit you now.

Being in good shape, you can go out and ride at a decent pace and feel fine, even when worn down. That is, until you really turn it on, like when you have to power up a hill. I think hitting the hill is just pushing you over the edge. (Believe me, I did the same thing after my freshman year of college!)

A little rest (a few days of easy riding) and you should be all set.

But then you have to remember to ease back into everything! You don’t want to jump straight into all-out efforts or you’ll be feeling it on your next ride.

It’s important for cyclists to do certain training drills to keep their skills sharpened. One drill I recommend you do is practice crashing!

Crash simulations are important drills for cyclists, especially mountain bikers. If you crash nearly every single race, like me, these drills help a lot!

The point is to practice the proper way to crash, in a controlled environment. Then it becomes ingrained in your mind, and when you crash for real (eventually you will,) you naturally crash properly and sustain as little injury as possible.

Here are two different ways to practice:

1) The Survival Roll

The “survival roll” is where you tuck and roll over one shoulder. (It could also be called a “shoulder roll.”) You may have done these during gym class as a kid. We had a “tumbling” day and did these. It’s also part of a typical high school football practice.

This drill will teach you how to roll through a high speed crash when you are thrown off the bike.

The basic maneuver

First, imagine you are being thrown forward through the air (because that’s when you use this move.) The basic movement is the shoulder roll, in which you turn slightly to one side and tuck your head so that the impact is taken as lightly as possible by one shoulder and dissipated across your back during the roll.

Depending on your speed, you may roll once then sit upright, roll a few times and stop, or roll once and end up back on your feet running.

The practice drills

First things first, location. I suggest practicing these drills in a soft grassy field.

For the first drill, start out crouched down on your hands and knees. Spring forward and perform a shoulder roll.

Next, stand up on your feet, but stay bent over. Lunge forward and perform a shoulder roll.

Next, stand up straight, take a step forward, and do a shoulder roll.

Once you are comfortable with the shoulder roll from an upright position, add some speed. Progress to where you are running and then dive forward, performing a complete shoulder roll.

If you want, you can even practice riding an old bike, slam on the front brakes, dive forward, and do a shoulder roll.

Tips

1. Start slow and progress as you get more comfortable. This is about practicing to not get hurt, so there’s no need to rush into it and end up getting hurt from the practice drills!

Take it one step at a time.

2. Do rolls onto both your left and right shoulders so you feel natural going either way. In a real crash situation, you could end up going either way.

3. Wear your cycling helmet and some pads at first while practicing. Not just for protection, but to make the drills resemble real riding conditions! If you wish, wear just your spandex and helmet.

2. The Slow Speed Fall

Sometimes when navigating technical sections at slow speeds, you will fall. But at low speeds, instead of rolling, you just kind of hit the ground and thud – so the survival roll won’t work here.

What you can do is increase the amount of time your body makes contact with the ground, decreasing the force of the impact on a single area.

The basic maneuver

Imagine you stuck your front wheel against a rock, lost all momentum, and you’re going down on your side. The goal is to lessen the impact.

First, unclip your foot as you fall. The side of your foot or calf muscle should hit the ground first, followed by your knee, thigh, hip, and shoulder. Do NOT stick your arm out! That is more likely to lead to a broken collar bone than to save your fall.

The practice drills

There is one drill here, but two places to practice it.

Start out on a soft grassy hillside. Roll along slowly then hit the brakes to come to a quick stop. At this point, fall over to the side. (Fall uphill, which will be less painful.)

Once you are comfortable with that, practice in a soft grassy field. You’ll fall a little further on the flat ground, so make sure you have the technique down first.

Tips

1. Imagine your body as a piece of rubber, rather than a piece of wood. See, you can snap a stick in half by slamming it on the ground. You could bend a piece of rubber or slap it around, and it could get bruised (if it had veins like we do,) but it won’t snap. (I’ll take a bruise over a broken bone any day!)

So when you fall, stay loose and relaxed. Be like Jell-O.

2. If you have good reflexes for getting your foot unclipped quickly, you might end up dabbing instead of falling over completely. That’s a better outcome, but watch out – you could get your foot stuck in a hole and twist your knee.

Now go practice crashing and ride safely!