Hello, this is Saita from Leomo.
Continuing from the previous post, I would like to look at the differences in position and pelvis/upper body movements during my preparation for the time trials.
When riding a TT bike, you assume a low, forward leaning posture in hopes to reduce air resistance. This position is generally said to be more difficult to generate power compared to a road bike. I want to look at the differences in MPIs between four different positions on two different bikes. The first position, holding hoods on my road bike, allows me to generate the most power. The second position, holding the drops on my road bike, allows me to lean more forward, but feels like I lose some ability to generate power. The third position, on my TT bike, feels the hardest to generate power. The fourth position is also on my TT bike, but with some alterations in position, which allow me to produce more power.
Figure 1. Pelvis and Torso MPIs on a road bike and a TT bike
See Figure 1.
Focusing on Pelvic Angle and Torso Angle, we can see that these MPIs were decreased from the holding hoods, to the holding drops, to the TT bike position. This is because the depth of the forward leaning posture increases.
What I want to discuss next is Pelvic Rotation. Before altering my position on the TT bike, my Pelvic Rotation was 8.9 degrees. This value was much larger compared to my position on the road bike. I changed my position on my TT bike moving the saddle 2mm backwards and 2mm lower. This position change brought my Pelvic Rotation down to 5.7 degrees and closer to the value on the road bike. At this time, there is not much change in Pelvic Angle or Torso Angle. It seems possible to create a position that maintains the deep forward leaning posture, while keeping the pelvic movements closer to what I experienced on the road bike. This adjusted TT position also allowed for more power generation .
Moreover, Torso Rotation decreased to 6.9 degrees after changing to the TT bike position, and it seems that the movement of the upper body is reduced and becomes more stable. With less upper body movement I am assuming that I will reduce my air resistance.
For me, as an athlete who trains mainly on a road bike, reproducing a similar movement on a TT bike may be key to not only feeling more comfortable, but also generating more power on my TT bike. Give this a try and see how your MPIs might change from a road bike to a TT bike!