Seat Height - How low can you go? No, thats too low....
Like most aspects of a good bike setup, seat height adjustment is a balancing act of compromising power and muscle optimisation, with risk of injury and overuse conditions. Excluding a heroic crash, most cycling injuries result from overuse of particular muscles/tendons, and getting your seat height correct is a great way to minimise repetitive strain through your lower back, hips, knees, and ankles.
Long story short:
Seat too low = Increased knee compression and shear forces
Seat too high = Lateral pelvic rotation and ankle loading
Seat just right = More power!
Historically there are a few methods people use to get a rough estimate of a good seat height; the LeMond method, the Hamely method, the Heel-Toe method, and Video Geometry method. The effectiveness and scientific support for these methods are discussed in my latest blog article, which will allow you to make better decisions regarding an optimal setup for your style of riding.
For a detailed biomechanical analysis of both body and bike, book a biomechanical bike setup assessment with John, visit 6s.com.au or contact our Mingara or Ettalong clinics.
Seat height:
There are a couple of easy ways to hurt yourself while riding a bike.
Crash
Ride too much and develop an overuse injury
For most cyclists, excluding any heroic stacks or interactions with friendly motorists, the main reasons for pain while riding is from repetitive strain to tendons or joints. Most people have the pre-conceived belief that a lower seat and slacker geometry is better for ‘comfort’ riding, and the opposite is true for racing. This is wrong.
Usually there is only a small range of suitable adjustability before both power and comfort are compromised. I have had a couple of clients in the past who were quite elderly and rode only short distances, so their ‘expert’ bike shop had set them up with a very low seat and upright riding positions. One of these clients couldn’t even ride up hills without significant knee pain and thigh muscle fatigue, but the bike shop dismissed her concerns and suggested her “knees are probably worn out, maybe you need joint replacements”…
Needless to say after making some very simple adjustments to her seat height, alongside other small tweaks, this client can now ride up hills without any pain or undue fatigue, and she now cycles almost every day for the sheer joy of riding. Moral of the story, if you have pain talk to a physio, and don’t take medical advice from a mechanic.
There has been a lot of published research in physiology and sporting journals on the best bike setup for improving outcomes for competitive and recreational cyclists. When delving into seat height optimisation, there is a pleasant consensus of what is suitable for most cyclists, and the difference in setup for professional vs. beginner cyclists is fairly small.
For starters, let’s discuss why seat height is such an important thing to get right.
Seat too low = Increased knee compression and shear forces
Seat too high = Lateral pelvic rotation and ankle loading
Seat just right = More power!
This is the simplest way of putting it. Cycling relies mainly on generating power from hip extensors (gluteus maximus >hamstring), and knee extensors (quadriceps), and balancing movements using synergists (hip flexors, calf muscles). The biomechanics are complex, but optimising the co-ordination of all these muscles requires all the joint angles to be creating a “mechanical advantage” at each stage of the pedal stroke.
A mechanical advantage describes the length-tension relationship of muscles, when compared to joint angle. In layman’s terms, how to get the most power out of a muscle with certain energy input. Therefore getting all your joint angles right, in just the right positions, with make you a faster and more efficient rider. Adjusting the seat height is a great way to optimise the hip, knee, and ankle joints, which are of course the most important bits for cycling.
Now that we can understand the need for getting the seat right, what is a good way to do it?
There have been a number of methods used to calculate the best seat height, from the very scientific and skeletally optimised, to simply “winging it” if it feels right.