PezCycling News - What's Cool In Road Cycling : Optimal Drafting Positioning For Team Pursuit Gold

ToolBox
Optimal Drafting Positioning For Team Pursuit Gold
Toolbox: The team pursuit is one of the marquee events at the Track Cycling World Championships, where optimal drafting positions and technique can make the difference between winning medal glory, or becoming footnotes in the cycling history books. Behind the enormous power and graceful beauty of the event lies an interesting question: how do we optimize the rider order?

Berlin - Germany - wielrennen - cycling - cyclisme - radsport - track - baan - Bahn - 2017 UEC Elite Track European Championships - Berlin - day 1 - 18/10/2017 - Team Pursuit - Germany GER - photo LB/RB/Cor Vos © 2017

The Ultimate Team Event
Road cycling is often described as an individual sport competed in by teams. In contrast, team time trials on the road, and team pursuits on the track, are true team events where the entire essence of the discipline lies in subsuming individual abilities for the greater good of the team. Not only can a weak or off-form rider torpedo a team performance, a very strong rider can equally destroy a team by not using their strength wisely.

Team Composition?
Besides pure power output and cycling ability, another critical aspect of improving TTTs may be through optimizing the team composition. This may be especially important when it comes to optimizing the aerodynamic and drafting efficiency of the entire 4-rider team pursuit squad.

For example, all else being equal:
• Should a team aim to have riders of similar size?
• Should a small rider be placed right behind a large rider?

Marginal gains, you scoff? Remember that in Rio 2016, the difference in men's qualifying times between 2nd (Denmark) and 3rd (Australia) was just 0.21 s, and 3rd and 4th (New Zealand) was 0.371 s. The competition is so tight that something as seemingly trivial as rider composition and order can easily make all the difference.

Heimans et al. 2017
My friend Jos de Koning at Vrije Universiteit Amsterdam in the Netherlands has done many seminal studies in modelling athletic performance in cycling, speed skating, and running. In a 2017 study in the Int J Sports Physiol Perf he co-authored a study with the purpose of determining "the drafting effect in second, third, and fourth position during the team pursuit in track cycling as a function of the team members' individual frontal areas in order to minimize the required power." (Heimans et al. 2017)

How did he go about testing this? They used a combination of field data and modelling:

• 8 national level Dutch track riders took part. Study was done at the Apeldoorn track, the same one hosting the Worlds this year.

• Each rider had their frontal surface area measured digitally.

• 39 x 3 km, 4-rider team pursuits were ridden with multiple team compositions. Riders kept their aerodynamic position as consistently as possible.

• All pursuits were done from flying start and at 15.75 m/s speed (56.7 km/h). Pulls each lasted 1.5 laps (375 m), such that every rider rode exactly twice in each of positions #1-4.

• SRM power meters were used on all bikes. Power and frontal surface were then modelled to determine drag fraction in each of positions 2-4. This was defined as the percentage of the absolute drag values when the rider was leading (position 1).

Berlin - Germany - wielrennen - cycling - cyclisme - radsport - track - baan - Bahn - 2017 UEC Elite Track European Championships - Berlin - day 1 - 18/10/2017 - Team Pursuit - Switzerland SUI - photo LB/RB/Cor Vos © 2017

Getting Up to Speed
Some of the main findings:

1. Rider height ranged from 177.5 - 199.0 cm, weight from 81.7 - 90.9 kg, frontal area from 0.336 - 0.411 m2, and drag coefficient from 0.545 - 0.593, power from 441 - 578 W. NB. Latter three values are when the rider is in position 1.

2. Power output in the 4 positions averaged 507, 334, 289, and 286 W. Drag fraction of positions 2-4 were 0.64, 0.55, and 0.54 that of position 1.

3. There was an interaction between the lead rider (drafter) and the draftee. One finding was that, as the drafter increased in size, a larger draftee benefited more than a smaller draftee. This makes sense as a smaller rider is already well-protected compared to a larger rider when drafting.

4. Team composition affects different riders differently. For a smaller rider, average power over all 4 positions ranged from 67.2% that of position 1 when teamed with large teammates, and ranged up to 70.1% with small teammates.

5. The same analysis for larger riders was 68.9% (large teammates) to 72.4% (small teammates).

6. For overall team efficiency, a team of large riders averaged 68.9% of position 1 power, while a team of small riders required 70.1%.

7. If a team consisted of 2 small and 2 large cyclists, a very small benefit of 0.18% power decrease occurred when the two smaller and 2 larger riders were paired together, as opposed to alternating small-large-small-large.

Overall, rider order can result in differences between 15-35 W power requirements to ride at test speeds.

The Black Line
A nice combination of real field data that was at the same time well-controlled. This was further enhanced by interesting modelling using the field data. Even if we're not riding pursuits or TTTs, how can we use this information during our next group ride?

Remember that, while test speed was fast, this is still well below current top speed competition speeds. The exponential effects of air resistance means the potential for improvements are even bigger.

The study again highlights the overwhelming importance of aerodynamics and learning how to ride wheels. Take the time to learn the skills to draft properly in different wind conditions/directions. In races, surf the sweet spot in the group to get the best draft to save as much energy as possible.

If you're a larger rider, do whatever it takes to slot into position behind another large rider. Do not get stuck behind a small rider.

If you're a smaller rider, you don't necessarily need to focus on getting behind the largest rider. Rather, focus on getting behind the smoothest rider, or the racing rival that you need to keep the closest eye upon.

Ride strong and have fun!

References
Heimans L, Dijkshoorn WR, Hoozemans MJM, de Koning JJ (2017) Optimizing the Team for Required Power During Track-Cycling Team Pursuit. Int J Sports Physiol Perform 12:1385-1391. doi: 10.1123/ijspp.2016-0451

Rio de Janeiro - Brasil - wielrennen - cycling - radsport - cyclisme - Women’s Team Pursuit - 13/08/2016 - Sarah Hammer - Kelly Catlin - Chloe Dygert - Jennifer Valente (USA) pictured during track day-3 - Olympic Games 2016 in Rio - photo LB/RB/Cor Vos © 2016




About Stephen:
drstephencheungStephen Cheung is a Professor at Brock University, and has published over 100 scientific articles and book chapters dealing with the effects of thermal and hypoxic stress on human physiology and performance. Stephen's new book "Cycling Science" with Dr. Mikel Zabala from the Movistar Pro Cycling Team has just hit the bookshelves this summer, following up Cutting-Edge Cycling written with Hunter Allen.

Stephen can be reached for comments at stephen@pezcyclingnews.com .

 

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