By Chris Myers, Ph. D
Peaks Coaching Group
The LEOMO Type-R is a wearable system that provides real-time biomechanical analysis of one’s pedaling motion. One of the components this system illustrates is changes in a triathlete’s pedaling acceleration through the pedal stroke (termed Dead Spots). The hypothesis is that significant amounts of dead spots in the pedaling motion reduces pedaling efficiency and power output. This case study explores ways to reduce dead spots and improve pedaling efficiency using the TYPE-R.
Background: The athlete is a mid-30s male, high performing age-group, short course triathlete. He rides a Quintana Roo (QR) CD 0.1 bike with a 53:39 x 11:25 gear ratio, 10-speed Ultegra groupset. Before using the Type-R, he was fitted professionally on his bike using the Specialized Bike Fitting System. The athlete has had 4 knee surgeries on his left knee that has caused a slight range of motion imbalance between his two legs. His tested FTP was 300W with no power balance issues. The triathlete’s initial intent for using the Type-R was to find the best positioning to place the Q-rings he had purchased.
Figure 1: Initial ride with LEOMO TYPE-R on normal circular 53:11 gear ratio.
During his initial ride, the Type-R displayed an extreme dead spot area at 12 o’clock position with the triathlete’s left leg (top left red circle in Figure 1). This was to be expected given the triathlete’s knee surgery history. Based on this information, I then had the triathlete install and place his Q-ring on position 3 based on the manufacturer’s instructions. (For more information go to https://rotorbike.com/how-to-set-your-optimum-chainring-position-ocp/)
Figure 2: Initial ride with LEOMO TYPE-R and Q-Rings.
The triathlete’s initial ride with the Q-rings did not change his dead spot. What the Q-rings provided was additional information between his leg range of motion imbalance. When comparing Figures 1 and 2, more dead spots are seen at the 6 o’clock position for both legs in Figure 2 versus Figure 1. Furthermore, more dead spots were seen across the varying range of cadence speeds for the left leg. With this information, no changes were made to the triathlete’s bike position since it was his initial ride on the Q-rings. What this information did provide was a greater insight to the triathlete’s range of motion imbalance and a possible need for a change in saddle height position.
Another aspect that taken into consideration were the shape of the Q-rings. These rings do naturally change one’s pedal stroke. During the initial ride, we did expect to see some changes to the pedal stroke; however, we did not know what to expect. The manufacturer, along with others to whom use this product, suggest riding with them for a week or two after installation before making any other changes. Keeping this advice in mind, this is the approach we took.
Figure 3: 6th ride with Q-rings.
Figure 4: 12th ride with Q-rings.
After full two weeks of riding (Figure 4), we noticed a striking pattern develop. The dead spot accumulation was consistently at the 2 o’clock position, not the 12 o’clock position (Figure 2 and 3). At this point, the triathlete felt comfortable with the Q-rings. I looked at the triathlete’s power data and saw no changes in power output. For example, in Figures 3 and 4, the subject did the same exact hill climb on Zwift. The power patterns are very similar. This data was a good sign the client was comfortable and produced stable performance with the Q-rings. The next step was to address the primary goal, reducing the number of dead spots.
Since the dead spots were at the top of the pedal stroke for both legs (Figure 4), this pattern is typical with the seat position being too low. The biggest question to address with this aspect of the bike fit was how much to bring up the triathlete’s seat? The metric I had available were the percentages of dead spots (dead spot score) calculated. In the top right corner of Figures 1-4, a red circle encompasses this metric. Through the three weeks of data I had collected for this athlete, his dead spot score ranged between 9-12. This score is high and is very indicative that the seat position is extremely low.
With this information, I took an aggressive approach and advise my client to raise his saddle position by 4 mm. This increase in saddle height reduced the amount of flex necessary in his left knee to come over the top of the pedal stroke. The deceleration at the top of the pedal stroke is very subtle and cannot be seen with current bike fitting systems.
Figure 5: First ride with increased seat height by 4 mm.
The changes in the dead spot pattern were almost instantaneous. The triathlete performed a 20-minute sweet spot interval during the first ride as shown in Figure 5. His dead spot pattern was almost completely changed. His dead spot score for the left leg changed from 9 to 1, and the right leg changed from 5 to 0.8. Additionally, we did not see any decrements to power output with this saddle height change.
Figure 6: Second ride at the new seat height position.
With the second ride, the dead spots were removed completely. During this ride, as shown in Figure 6, the triathlete complete 2x20 min sweet spot intervals. Figure 6 shows both these intervals. The dead spots are nonexistent during both intervals. Even though this is not shown, power did not degrade during the second sweet spot interval even as the triathlete grew tired.
After these changes were made, the triathlete performed an FTP test. His FTP increased by 4%. Furthermore, he had a 2% increase in his fatigue testing as well. Part of this is due to the function of the training plan; however, the bike position changes made a remarkable difference.
This case study highlights how the Type-R can assist in perfecting one’s pedaling mechanics to improve efficiency. In the case of this triathlete, the increase in saddle height improved power output and time to fatigue. These changes improved the triathlete’s performance and helped him to reach his goals for the season.