Comment by idoubtit | Hacker News Reader

Comment by idoubtit | Hacker News Reader

This paper repeatedly asserts that the formations they studied have a practical impact for professional cycling. They claim that, to bring back a leader into the peloton, the teammates could use formation different from the usual single line. For example, 2 riders upfront shielding 1 protected rider behind them. Or a diamond of 4 riders, with the protected one in the back.

I doubt this practical value exists. The paper completely forgets one important element¹: having a single rider at the front saves the energy of the teammates. If a team was to put two riders upfront and then the chase takes more time than expected, they have no backup. And even if the strategy was to succeed and the leader gets back into the peloton, he/she will have two tired teammates instead of one, which means a reduced help for the remaining of the stage.

I also suppose pro teams already know all of this, even if they didn't have the precise benchmarks of this paper. It's just unpractical most of the time. For a diamond shape, the aerodynamic gain is pretty obvious, but with a high price to pay in order to protect a rider.

As a side note, the paper authors should learn about PDF metadata. It's quite ugly that the file's title is "Microsoft Word - 2025_Preprint_Formations_V2".

[¹]: Except when they quote a cycling specialist about the goal to "reduce the leader's effort without sacrificing too many team members".

>having a single rider at the front saves the energy of the teammates

Also (as mentioned briefly in the paper), longer pace lines result in reduced drag for the rider at the front. This can seem counter-intuitive, but it's basic streamlining - the following riders fill in the low-pressure region behind the lead rider, reducing the amount of flow separation. Riding two-abreast is actually slower than riding individually.

A really efficient pace line looks like a team pursuit, with the rider on the front doing very short stints before peeling off and joining the back of the line. This is hugely important for physiological reasons, because it allows the lead rider to briefly exceed their aerobic threshold and then recover.

https://www.sciencedirect.com/science/article/pii/S016761051...

https://www.youtube.com/watch?v=pSq_JvD9w0g

Yeah, this is how you do it. Everybody pulls but the protected one. I've been in team time trial situations where we had to protect one (it me, but we won), even two, and goddam that pull through could be hard but I made it.

CFD simulation indicating leader is assisted by followers: http://dx.doi.org/10.1051/epn/2013102

Ah I see your cite shares the same lead author. Likely a better paper.

Really efficient pace lines are basically diamonds with the exchange of riders at front which usually only do 10 seconds of exposure in front tops.

In addition to this - single file pretty much always works. Quick cornering two+ abreast can be spicy.

Yeah if you watch crits you can tell from a still image whether it's fast or not by looking at the grouping. It strings out into a line when it's fast.

I watched a lot of the Tour de France and if I had seen the paper before that I would have looked out for any of these formations with two riders in front. Were there any instances where they used these formations? I only remember single leader formations (often lead by Tim Wellens for an impressively long time), but there might have been other formations that I just missed.

> Were there any instances where they used these formations?

Half of it, when in echelon form during crosswinds. Which is pretty much the only situation where any of this will work in practice since as mentioned elsewhere many times you don't burn all your people at once. Energy isn't endless.

To add to sibling comment, in the peleton you generally dont have the luxury of choosing your formation down to such fine detail. Theres lots of other riders fighting for space.

And breakaways are rarely a team affair. You get some towards the end of mountain stages, but uphill all of this maths goes away (everyone is much slower and air drag matters less).

At least with the diamond formation you have the opportunity of rotation but the two in the middle will still tire quickly, and I don’t know how you safely rotate in that configuration. Any beginning serious cyclist can learn to draft. But the pros have got rotating the formation down to a science. You have to go fast without increasing the risk of high speed collision.

In the scenarios mentionned ( getting back to the front ), usually the single line is the easiest to do because of the riders having to navigate between the team cars, road furnitures, dropped riders, etc. It is only really when you are at the front where you can go wherever you want.

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