Why should I ride a Steep Seat Angle for a Triathlon?
Andrew Budge

A topic of conversation that is bound to cause controversy! I will attempt to explain the reason why an athlete who is time trialing in a triathlon and then running off the bike would be best served to ride in a steeper seat angle position or use a frame with that style of geometry.

Firstly let me clear up a common misconception. There is not one particular seat tube angle that is ideal for everyone. An individual’s body proportions must be taken into account. What determines their optimal seat angle specifically is, the length of the athlete’s femur (upper leg bone) relative to the length of their Tibia (lower leg bone). In action, the tibia serves as a connecting rod to the femur. The longer this rod, the higher the Femur will be pushed upwards towards the torso when the cyclist is in the upstroke of the pedaling action. If you combine two other commonly occurring factors, like the seat height being too low and the seat angle too far rearward then problems in efficiency result. Let me expand. There is a point of biomechanical disadvantage where an acute angle is formed by the torso to the thigh (closing the hip angle down or thigh hitting the chest). The resultant outcome is a loss of power, pelvic instability (rocking from side to side on the saddle as a result of the thigh hitting each side of the torso alternately), excessive fatigue/tightness of the gluteals (thigh extensors) { I think a contributing factor to Illiotibial band problems with subsequent fatigue and then tightening of Glute Med.}, lower back and cervical spine/neck fatigue/pain and an inability to run well off the bike.

In general terms the longer an athlete’s femur is as compared to the tibia, the more rearward the athlete’s position can be because the connecting rod to the femur will not push their thigh up too high and cause an irregularity with their pedaling action. Realise that crank lengths and the flexibility of an athlete are also a consideration here.

How do I know whether or not I have a long or short femur relative to my tibia? Firstly you must be aware of how to accurately measure these bones. Anatomical landmarks for the femur are the bony prominence on the outside of the hip (greater trochanter) to the bony prominence on the outside of the knee (lateral condyle) of the femur (proximal to the joint line at the knee joint). It is between these two points that one measures in order to determine femur length. The landmarks for the tibia are the medial condyle of the tibia (just below the joint line of the knee) to the centre (most prominent point of the bone) of the medial malleolus. Then divide the femur length by the tibia length. If the resultant outcome is less than 1.2 -1.25, you would be most likely to require a steeper seat angle position, if the outcome is 1.25-1.3, you would be most likely suited to 76-78 degrees. As stated, this recommendation is not absolute, as there are other considerations that can effect the position, but it’s where I start in regards to the initial bike set up process.

The advantages of a steeper seat angle for the triathlete are basically two fold. It allows the athlete to maintain a higher cadence, with optimal power application through a greater range of the pedal stroke. This is because when a rider sits further forward relative to the bottom bracket, it opens the hip angle out and allows the joints to work faster in action. There is less impedance of the thigh by the torso. Secondly, if the athlete is well suspended/equally weight distributed between seat and elbow pads, combined with a steeper seat angle, the lower back and hamstrings are less likely to be excessively fatigued. This fact has huge implications for how well the athlete can run off the bike.

How many times have you been riding in a Time Trial or Triathlon and realised that you are sitting on the forward end of the seat? Without realising it, you are creating a virtual steeper seat angle. I see it all the time in races where athletes have 2/3rds of the saddle visible rearward when they are cycling in a time trial position. Wouldn’t it be more comfortable if you could sit in the middle portion of the saddle? I think so, especially for a 90 or 180km cycle leg!!

The absolute reach is shortened substantially in the aero position when using time trial bars as compared to riding on the hoods or the drops. The arms are flexed at or close to 90 degrees thus shortening their length. Because of this, the torso is lowered closer to the thigh, closing this angle down. Rotating the rider around the bottom bracket offsets this issue as well as reducing frontal surface area and improving aerodynamic efficiency. Implications of closing the hip angle markedly and compressing the lower abdomen, other than effecting locomotion, are reducing ones breathing efficiency and perhaps even digestion.

I often get asked “ what frame should I purchase?” or hear “so and so reckons that I should ride at 78 degrees or 76 degrees” .

Remember that the bike should fit you, not visa versa. Realise that every application has its specific requirements and the athlete will be much more efficient if their equipment fits them best. The equipment should be best suited to the application they intend to use it in, keep this in mind. If you are a triathlete, get a bike that suits the application, not a frame that was designed to be used for a road racing application that you will have to ‘retro fit’ for the purpose of Time Trialing or triathlon. This will likely be a compromise.