Hello, this is Saita from Leomo.
In this article- Part 4 of the time trial series- we will discuss Head Angle. In time trialing, where one of the main objectives is to reduce air resistance, the angle of your head can have a big impact on overall time. In a slightly unorthodox way of using the TYPE-R's motion sensors, we attached one of sensors to the helmet (Figure 1), to allow us to measure the angle of your head. The head angle MPI, along with the pelvis and torso angles, can give us a better idea of how the entire upper body is positioned.
Figure 1: Location of sensor on the helmet
To make reviewing the data easier, we recommend first riding on the trainer to dial in your helmet angle so you can have a more concrete number to focus on when you are out riding on the road. As you can see Figure 2, the head angles are very different between the left and right positions.
Figure 2: Head Angle differences as seen from the side on the trainer (Left: Head Tuck position, Right: Slight Head up position)
We also compared the TYPE-R data of Head Angle and Torso Angle when in the head tuck position and in the slight head up position while riding on the trainer (Figure 3). The Torso Angle is about 10° in both positions, however, the Head Angle, while in the head tuck position is about 40°, and is closer to 65° in the slight head up position.
Figure 3: Head Angle and Torso Angle while riding on the trainer (Green line- Head Angle, Blue line- Torso Angle)
Next, if we look at the Head Angle and Torso Angle on a flat, straight section of a race (Figure 4), you can see that the Torso Angle is about 10°, and the Head Angle ranges between 35° to 55°. For most of the race, the Head Angle is above 40°. With this information we can see that it's difficult to maintain the ideal head tuck positioning with high intensity. It is important to note that maintaining this aggressive position, with a lower head angle, throughout an entire time trial might be unrealistic due to the lack of visibility, especially on more technical courses. The Head Angle MPI can give you great insight into your ability to maintain an aggressive position throughout a race. By collecting data overtime you can track your improvements from both training sessions and races.
Figure 4: Head Angle and Torso Angle during a race（Green line- Head Angle, Blue line- Torso Angle）
In addition to the method for reducing the Torso Angle that we covered in Time Trial Observation Part 3, you can also use the Head Angle to find better position, and reduce aerodynamic drag. Using the TYPE-R, you can accurately identify more complex situations with the data and breakdown exactly how you are positioned throughout a time trial race.