New study shows quantifies air resistance savings inside a peloton

[Mark McM]

https://www.sciencedirect.com/science/article/pii/S0167610518303751

A new study published last month in the Journal of Wind Engineering and Industrial Aerodynamics has looked at the air drag reduction inside a large peloton of cyclists, using both CFD (Computation Fluid Dynamics) and wind tunnel tests. Their results show that riding inside a peloton can reduce drag to as little as 4% of the drag on a solo cyclist. Additionally, they show that the rider at the front of the peloton also has a drag reduction, experiencing only 86% of the drag of a solo cyclist. Also studied was small groups of cyclists, including single pace lines.

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My personal take: I've ridden in large (100+ rider) pelotons at speed, and the reduction in power required to maintain a given speed is reduced dramatically. But in my experience, the air drag is not reduced to only 5% compared to riding alone. My perception is that the drag reduction is closer to the results of previous studies, which show that air drag inside the peloton is 50% - 70% compared to riding alone.

[drewskey]

My personal take: I've ridden in large (100+ rider) pelotons at speed, and the reduction in power required to maintain a given speed is reduced dramatically. But in my experience, the air drag is not reduced to only 5% compared to riding alone. My perception is that the drag reduction is closer to the results of previous studies, which show that air drag inside the peloton is 50% - 70% compared to riding alone.

I immediately thought of "no model is right but some are useful." The theoretical CFD/wind tunnel here tried to quantify what has been legend and lore for a long time.

But as we know, the real world is messy and we aren't mannequins standing at attention.

I too doubt the 5% rule, but I don't think it stops at 50% reduction. I can see 25% of effort being achievable in relatively small groups of 10-15 persons depending on terrain, wind speed, etc.

Power meters are so common now that I think a real world test might be possible with some highly selective individuals. The test setup would be hard to control obviously, but it might give a better real-world account for the infinite number of variable occurring every second.

[cachagua]

First thing I noticed is the neat regularity of the arrangement of "riders". I've marched in a parade that looks a little like that, but never seen anything like that in a group of riders. The static and essentially imaginary model they're using seems unlikely to reflect reality.

[jb_11]

I would think there would be at least a little uptick in effort required for the back row. All that turbulent air spilling off the back has to create some extra drag the the middle of the pack doesn't experience.

[vqdriver]

what i want to know is why an attacking rider is suddenly anchored to the ground because someone gets on their wheel and 'neutralizes' the attack.

[bigbill]

Those guys seeing 4% of the drag of the riders on the front and also moving up and back within the slinky-like pack. This probably applies to pro or high level amateurs, but the saturday morning group ride not so much, but still some.

[Ralph]

The NASCAR guys know all about that science.

[redir]

The problem with being in the back is the accordion affect. Sometimes the peloton stretches like a rubber band and if you are in the back you have to work hard to keep up while the front actually has it easy. I was just talking to a teammate yesterday and we were wondering if us as lowly amateur racers could at least hang with the pro's on a flat TDF stage if we surf in the peloton. As a cat 2 racer I've gotten in some big pro 1/2 races before and what I found was I could hang for the most part but there was no way I would be able to actually break away solo or even in a group. The middle toward the front is probably the easiest place to be.

[JimmyTango]

what i want to know is why an attacking rider is suddenly anchored to the ground because someone gets on their wheel and 'neutralizes' the attack.

https://i.chzbgr.com/full/6609015296/h8D2CCA1D/

[cash05458]

next up...a study that shoes help feet...