Pack Dynamics 4 Release [April 2023]

What’s the purpose of making it harder at the back?

Why did you say I was the only person complaining of being braked mid pack when it was an intentional design feature to brake people mid pack?

It’s not at the back, but generally in the whole pack. The purpose was to make progression inside the pack more difficult than before, to introduce the equivalent of navigating inside a real life pack, where you can’t just float through but have to fight a bit for position (I know it’s still not the same).
And also potentially decrease the speed of the pack.

Why did you say I was the only person complaining of being braked mid pack when it was an intentional design feature to brake people mid pack?

Currently, at least that I’m aware, you seem to be the only person complaining about how the system works :thinking:

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in practise, it isn’t. i’ve been autobraked (apparently) while sitting last wheel a couple of times, usually going into a tight corner, but it doesn’t actually make any practical difference. if i taped over the watt display on my monitor i wouldn’t notice it

You should’ve messaged “it’s supposed to brake you mid pack to make it harder” from the beginning if that was the intent.

Most people don’t notice or care, or have recognized that feedback won’t result in any changes. I also recognize that my feedback will have no change in outcome but still feel need to point out what appears to be broken. Even though frankly the effect is pretty minor and generally doesn’t have any real impact. Now apparently it’s intentional. And still don’t take Into account power being reduced as a result of terrain rolling down. Bad method to influence pack speeds but at least I know now it’s what you intended to do.

The real thing to address is reducing trainer resistance as a result of draft. Hopefully that’s up next after 4.1.

That’s the part where you’re wrong. I read all the feedback, and I already worked on a few extra safe guards to try and prevent situations where auto braking doesn’t feel right.

The focus now is on testing and refining the 4.1 version. More test events tomorrow: Pack Dynamics 4.1 - Test Events - #147


Michael, I’m not fully up to speed on what is out there amongst all the Pack Dynamics threads but the one below David put out in January and I think it covers a couple of the areas you have recently been questioning ( apologies if I am way behind the latest info)

Main Points:

Hey racing community!

We are back for another round of tests for Pack Dynamics 4.
I would like to outline in broad terms what has changed since the last version and what to expect coming into the next round of test events.

  • The concept remains the same - reducing the free forward motion inside the packs in order to reduce excessive speeds. Moving up in the pack should feel different (harder?).
  • With this version there was a change in logic in terms of how auto-braking works. It’s now more focused in the transition from medium to low draft whenever the Zwifter reduces power and is overtaking someone. This doesn’t mean it will happen only in the front (or near the front) of a pack, but mostly.
  • The previous system (auto-braking in high draft situations) is also still at work, but much less aggressive and mostly used for certain scenarios like when someone sprints at the back of a pack and then stops pedalling but still overtakes the whole pack or close to that (just a possible example).

If there was no red flash you wouldn’t even have noticed any chance.

I think most of people see the flash of red and realized that nothing notable happened and continue racing.

I’ve never been braked advancing through the pack, it’s only harder to move up because pack speeds are higher.

Suddenly not advancing with the momentum I worked for is something noticeable. This was actually a pretty hard brake. If nothing notable is happening then maybe it’s pointless to brake at all.

Why should this be less frequent towards the middle or back of the group? That’s surely high draft, meaning that the rider will definitely be braked whenever they ease off for any reason.

Because, generally speaking, reductions of more than 70% in power are not that frequent. Also given the conditions, auto-braking only occurs if your speed is higher than those in front of you. There could be situations where you are in high draft, reduce your power by more than 70% but your speed is not greater than those in front. So, lot’s of variables.

The thing I find a little difficult to get my head around with this want to regulate the pack churn and bring it closer to a road feel is that the speed in Zwift is just too high to replicate real road racing. When you race on the road or CX there is a constant change of speed, from braking in corners to being strung out due to road features or the terrain – That change in speed means you can actually move around and move forward fairly easily at times as you don’t need to exert huge effort to get in front of people. Zwift presumes that you are travelling at high speed, all of the time, so it is always difficult to move forward. The focus should be on how speed is applied or reduced rather than racing everywhere at 40kph. It seems a slightly backwards way of dealing with speed

I get there are large stretches of areas like Tempus fugit where pack speed & dynamic would need to be looked at, but take crit city for example, breaking for corners would significantly reduce the speed of those courses and change the entire race dynamic.


That’s why I’m working on PD 4.1. I’m quite hopeful that the release coming out mid June will bring a lot of positive changes :wink:


Isn’t this something that’s (supposedly) being worked on? Funny that we never hear any updates from Zwift about this :thinking:

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It’s currently paused due to other priorities, but still in the plans.

Fixing CE taking priority?

Worth a shot :wink:

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Want to check in on the 70% power drop requirement.

Here I am doing 127 watts a power drop of 70% or more means I would had to be doing 400 watts+ in the previous 10 seconds. But as you can see we are chilling in the tunnel and no one pushing, so we wouldn’t have done 400+ watts prior. My average 1 min power is around 192 watts at this point.

This is the extension to the youtube video /watch?v=8Bekvq0oq5o&t=1831s&ab_channel=WilliamNg

You are right, but there are many other things that you are noticing while you are racing. One thing is that the gap between you are the rider in front doesn’t close or it widens. To offset that you will push more watts. At the end of the day, the end effect is do you need to push more watts. If you do, then you notice it.

Please read my other post, 2 posts down from the one you replied from :wink:

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It’s pretty obvious to me that the lack of breakaway/late attack comes from the lack of penalty for riders in the draft in large groups. When a large group of rider enter a corner the first rider choose it’s line so the corner is easy for him but he had to ride at the front which was obviously harder. All other rider have to find room and are forced to brake for compromised lines and position. It’s also a domino/additive effect if you are way back in the group the group will be strectched and you’ll have to wait a long time even before entering the turn. After this event you will have a very hard time sprinting to keep up with the front of the group.
All this penalise the big group compared to the breakway. It would make for very different/more interesting racing at crit city for example. But it would be true for most non pure climbing tracks. It might even make climbing races more interesting too because going down the mountains pack have a big drafting advantage on breakaway while irl breakaway usually go down pretty fast because they can ride their line.
In the end programming a braking behaviour to keep some distance between rider or to take corner at a somewhat realistic speed would automatically solve many pack dynamic problems in one stone. Racing would definitely be more interesting.