Pack Dynamics 4.1 - Test Events

That’s done


Thanks to those who provided feedback and recordings. Your comments are in line with what I predicted.
The way to go is a middle ground between last week and yesterday’s configuration.
I have collected enough data and feedback to adjust the system.

We will pause test events for now, until the Zwift 1.42 released (mid June), that should hopefully contain the first stable version of PD 4.1. After that we will resume test events and I’m confident it will be ready for the adoption by some race organizers that wish to use it.


Thanks for all you effort @DavidP and testing all these different options.

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Really appreciate all the work you’ve put into this.
Can’t wait to see the finished product!!

Will the PD 4.1 you’re releasing in mid June be somewhere between last week and yesterday’s configuration? Or will it just be a small tweak/improvement?

Like I said above, I think it will be a middle ground between the type of settings used in both sets of test events.

Did not do it last week, but did yesterday’s last race in B’s.

My first reaction was the draft numbers from S4Z were off the chart in the descent.

Much (double?) higher than what I normally see. This was most obvious in the first few minutes of the descent in the big group.

Do you have a sense of the impact on average speed for this iteration?

It’s very difficult to compare speeds in an objective manner, because so many variables can change. Mostly pack behaviour due to differences in power applied, road gradient, etc.

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Here you go cause you asked nicely :smiley:

PD 4.1 (30th May) ZwiftPower - Login

PD4.0 (17th May) ZwiftPower - Login

Conclusion…there was almost no difference between PD4.1 (Test 2) vs PD4…the group was still to fast because of the churn on the front…the break had no chance once the group starter rolling on a false flat downhill.


I think that it is true to some degree, but it still has some value given how much we’re relying on subjective/anecdotal feedback to drive changes.

Hey Zwift racers!

With the release of Zwift 1.42 (finalising today), we are ready for another round of Pack Dynamics 4.1 test events (and hopefully the last).

We are setting up events for next Tuesday and Wednesday that you can check out here: The at Home Cycling & Running Virtual Training App
(once again it will be 2 laps of Sand & Sequoias)

Please spread the word so we can get more folks in the events.

Ride on!


Bumping this topic for more visibility on the test events this week :point_up:

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Didn’t notice any difference with PD 4.1 against other races previous (with PD 4)

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Are you sure,…i’m just watching stream of @Arend_teRaa and it looks much better with the movement in the group and the pace looks lower.


Everything seemed to work for me. I didn’t experience any blocking that others had in the first race nor did I see anyone else complaining about it for them.

It sure felt like the pack was slow when no one was pushing at the front, we spent a lot of time with our speed in the mid to upper 30 km/hr range which I would say is not typical for a B race with 30 riders. There was a group of 3 that were able to get a 15s gap that was only closed down when people started chasing pretty aggressively. At the start of the second lap there was a small chase group of 3 or 4 that was about 15s down and was able to get within 4 or 5 seconds of our group of 20 by doing ~3.8-4.0 (and then someone decided they weren’t going to let them catch - sorry guys, lol!)


This is what PD 4.1 was designed for…it worked perfect.


That sounds like good news. Both feedbacks.
So it wasn’t a too disruptive change to cause a major difference, but it seems to be checking all the boxes on the proposed improvements from what I’ve seen.

Tomorrow there is another set of test events, just like today.

If things go well, it will soon be available to event organizers that want to start using it, so we can start “evangelising” it.


Just did the first lap and a half of the B race. First lap was fantastic - stable pack movements, predictable draft (with one exception, see below), speed felt more reasonable. Two issues:

  1. I’m sure you all are excited about steering being more accessible, but it needs to be disabled in events or the wheel following logic needs to improve significantly (or allow us to steer with the keyboard or companion app). On the last lap in the desert we had a rider get clear just by weaving back and forth and then doing something which looked like microbursting. A few times I tried to close a gap but it would get pushed right back out because my rider just didn’t follow the wheel. It looked comical but would be insanely frustrating in a big race.

  2. There are occasional situations where in single file lines the rider in front of me would be getting pulled away from me while I was doing higher watts within 1 meter of their wheel. Usually the rider in front of them would be doing slightly higher w/kg, but it was the only area which felt like it could use some work.

Overall it was solid. Kudos to @DavidP for putting so much work in to this!


that guy was driving me nuts but i can’t be sure he was actually doing anything wrong and i don’t think he would have gotten anywhere in a bigger field

overall, feels fine, no complaints. descents are making me nervous, but maybe it’s just me.


Hah glad it wasn’t just me! I think you’re right - in a large group it probably wouldn’t have mattered, but I’d hate to see someone win out of a break like that when there isn’t an easy way to counter it.