If you’re wondering why are mountain bike seats so high, you’ve come to the right place. I, too, was wondering why because before you know the reason, when you see a mountain bike set up correctly, it looks like you would be sitting so far up that you wouldn’t reach the ground (which is apparently the way it is supposed to be). But why? Let’s find out!
The rider’s leg inseam length determines the height of a mountain bike seat. In order to maximize pedaling efficiency, the seat height is adjusted to allow the rider to reach near full extension of the leg upon the maximum downstroke of the pedal rotation cycle.
Unlike some other forms of biking like BMX or even road cycling, the mountain biker is concerned with ultimate power efficiency. Unlike road cyclists or BMX, mountain biking requires a versatile balance of efficient riding, comfort, and the ability to handle steep and sudden terrain changes.
To fully understand the reasoning behind the mountain bike seat height compared to other forms of biking, we really need to look at the needs and the physiological facts that support the reasoning behind higher seat placement. Join me on this ride into the unknown world of mountain bike seat height, won’t you?
Why are Mountain Bike Seats So High? Here are 4 Reasons
There are four primary reasons why mountain bike seats are so high. These reasons also stand as the benefits when you understand the meaning behind each. I’ll explain what I mean in more detail for each.
- Joint Health
If you’re a mountain biker like me, then in my experience, you want to have as much power as you can. In fact, if you’re like me and many others, then it might even be partly obsessive, but you need to squeeze every Newton you can out of your legs and ride.
When you understand the physiology of the human leg and the positions and movements that derive the most significant power, you know that the downstroke of the pedaling cycle is the place we want to concern ourselves with maximizing the efficiency of our leg’s pedal stroke.
The average cross-country mountain bike racer will use their heart to approximately 90% of their maximum heart rate during a race. We can assume that most of us will push ourselves similarly when mountain biking. No one pushes themselves and does not want to increase the power output, right? Especially when mountain biking can take upwards of 500W of power to ride a steep climbing slope. (source)
You already know that maximizing power on the downstroke of the pedal cycle is vastly essential to all mountain bikers. However, unless you want to push really hard for a few minutes and call your ride over, efficiency is equally essential.
In combination with the utilization of maximum power from your legs, you want to ensure that you can maintain that power for an extended period.
With a seat height that is equal to just below your maximum inseam to floor measurement, you ensure that your leg can provide maximum power in a natural movement. This natural movement allows the leg to perform at the most incredible efficiency. Just think how uncomfortable the ride would be if you had to move your leg in an awkward position each pedal rotation. The natural movement cycle of the pedals must follow a comfortable natural movement pattern of your legs. The more similar the movement to the pattern of natural walking, the more efficient the cycle.
Natural walking means your leg is full to very near fully extended below you. This position is mimicked below the hips by a high seat position, allowing for maximum leg efficiency.
Coinciding with efficiency is the position sequence of the pedal cycle that extends the most comfort to your legs. As mentioned, a natural motion that follows your physiological movements will be the most efficient and the most comfortable.
Depending on what kind of mountain biking you are doing, you may need to ride for extended periods. According to a study of the physiology of mountain biking in Sports Medicine (source), the physiological characteristics noted when mountain bikers were studied found that aerobic power (VO2mx>70mL/kg/min) and “the ability to sustain high work rates for prolonged periods” are prerequisites to the sport. With such demands, the necessity for a comfortable seat height position becomes a requirement. I’ll discuss more about determining the ideal seat height for you (I even created a formula to calculate it, keep reading to find out more).
There would be nothing worse than blowing out your knees and not being able to ride again. That being said, let’s look at the last reason why mountain bike seats are so high – for the health of your knees and joints.
As mentioned, when you extend your legs to almost full, you maximize the power, efficiency, and comfort of the downstroke part of the pedaling cycle.
However, maximizing your comfort by mimicking the natural walking movement of your legs allows your joints to move in a natural way. Natural movement is what we want. Unnatural movement can cause damage to your tendons, cartilage, and your joints in general.
Furthermore, using a proper movement cycle by having the seat of your mountain bike at the appropriate height will allow you to build the muscles in your legs naturally. Strengthening the muscles that support your knees has been shown to be a critical aspect of improving and maintaining good knee health. (source)
There are two ways to determine your ideal seat height:
- Physically get on the bike and measure/set the height.
- Measure your inseam and follow the formula:
Fi = Full inseam length (crotch to floor)
Si = Sewing inseam length (crotch to the ankle, or the medial malleolus – the boney ball that protrudes from the inside of your ankle)
I derived the formula while trying to come up with the perfect seat height. The idea is that the total inseam minus the sewing inseam gives you the height of your ankle. Divide the height of your ankle by two and subtract it from the full inseam length.
This measurement gives you nearly the full extended leg length but leaves your knee ever so slightly bent. In other words, it works perfectly to set your mountain bike seat height based on measurement, so you don’t have to try to balance on your bike while trying to measure, adjust or tighten your seat at the proper height.
Looking for different ways to make your MTB more comfortable? Read my article on 10 Ways To Make Your MTB More Comfortable
Does Elevating the Seat Help with Balance?
Some state that raising the seat and thus the center of gravity will improve your bike’s handling. It may not necessarily be true, though.
Take a sports car, for example. The lower the center of gravity, the more stable the balance. The higher the center of gravity, the more difficult it is to balance – ask anyone who has ever tried to use stilts.
So, why would we raise the seat if it decreases balance? Let’s look at two main concepts: first, the four benefits stated above counter any possible advantage of a lower center of gravity. Second, the relationship between your inseam length and the seat’s height is vitally more important than the potentially small amount of extra balance one might get from a slightly lower center of gravity.
I mean, you don’t generally fall over when walking, so standing height is a natural height for humans to control their center of gravity. Mountain biking only extends this height by a few inches off the ground or the height between the ground and the pedal (or your foot) at the lowest point of the downstroke of the pedaling cycle.
It is true that a lower bike, such as a recumbent, for example, will have a much lower height and thus a much lower center of gravity. But I wouldn’t want to try the rigors of a mountain bike trail on a recumbent, that’s for sure.
With all said and done, the height of the bike seat, if set up correctly according to the specifications as mentioned above, is the best and most efficient, most comfortable, and least damaging height for a mountain bike seat.
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David Humphries is the creator of DIY Mountain Bike. For me a relaxing day involves riding my mountain bike to decompress after a long day. When not on my bike I can be found wrenching on it or casting a fly on a small mountain stream. Read more about David HERE.