Pack Dynamics 3.0 Update [October 2021]

Did the ZHR masters this morning, same route as last weekend. Same time for less effort but that’s possibly due to the slightly larger group size. Much smoother ride, very easy to position the avatar and much less sticky draft. There was still the odd occasion where riders swung across the lane but it seemed less common. Supertuck on descents seemed more stable and reliable, I never once thought I was slipping out of the draft which has happened in the old version. Could be just coincidence or confirmation bias.

I think TTTers will really like it though it might take a week or two to get used to. Please roll out to all worlds ASAP, I don’t want the old version!


That’s pretty much the same feedback I got from the ZHR Weekend Group Ride - smoother, more stable, easier to stay in the pack, not getting pushed sideways out of the draft, same speed for less effort, etc.

I’m with you - please roll it out to all worlds! :+1:

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@Mark_Crane_TOG_G_65y yea I’ve been putting that off cause IIRC you can’t use the top right hood button to activate power ups if connected via ANT+. It only works in BLE

There are several of these inexplicable inconsistencies, such as the Wattbike gear indicator only working over Bluetooth but controllable only working over ANT+.

?? Atom user here…
What do you mean?

This is on Windows, which IIRC you don’t use.

Windows Bluetooth is the version I don’t use… Windows Ant+ I reluctantly still use every now and then. You can’t move from erg to free ride to erg whilst in a workout on Apple TV so is needed.

Ant+ on windows is pretty good, I just suffer massively from drop outs which im not convinced is all ‘noise’ from other devices.

We’re off topic, point was just that if a device or hardware feature is supported, it should be supported over every protocol and platform.

Has anybody raced with PD3 yet? Interested to know how different it is, particularly in a chase pack. Do you need people actively working to chase back a break? Does it feel like you can take advantage of a slower moving pack and attempt a breakaway? Is it easier / same / harder to benefit from a peloton and hold position at the back of a group?

The cosmetics are drastically improved, with much of the sickening side to side motion removed and riders moving around each other more smoothly, but the update is mostly window dressing that disguses a lot of the major mechanical issues with the draft rather than fixing them. Sticky draft appears to have been mostly fixed but that’s about it in terms of improvements to practical mechanics.

The pack speeds are still far too high when there are no riders pulling hard at the front. 30 riders at 3 W/kg should not be catching 1 rider at 5 W/kg, or even 4W/kg for that matter. This is a major issue that has been unaddressed for years and really blights racing on the platform, drastically reducing tactical options and teamwork.

The emphasis on power:weight over pure power over is still far too great, with light riders travelling far too quickly on flat roads relative to large riders putting out much more power. The height effect on speed is also greatly overstated.

There are still a lot of issues with the draft disappearing, particularly at high speeds where it should be strong.
The most consistent case of this occurs anywhere where the gradient changes from an uphill into a downhill, riders in the front accelerate unrealistically quickly, and the draft pretty much disappears for riders in the back section of a group, even if tight on a wheel, just at the point when the draft should increase dramatically as the speed goes up and the gradient goes down. You have 80+kg riders having to push 4-5W/kg down a hill to match the front who have eased up at 2-3 W/kg, even though they are all on a wheel.


ZHR masters was a race. I thought it was pretty similar tactically, perhaps slightly easier to cycle defensively in a small group going up Box Hill as I didn’t get stickied off the leaders and could more easily move up to tail them. One guy went off the front on the flat and no-one bothered to chase (not my age cat!). I’d say it’s easier to do what you want to do, whether that means chasing or not. Less of an automatic washing machine effect at the front of a pack, and also less blocking from marginally slower riders. I wouldn’t say it’s radically different however, just generally more pleasant.


Is this likely switched on in Yorkshire by Tuesday’s ZRL races?

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Thanks. Sounds like a good improvement, and hopefully a foundation to touch of some of those elements mentioned above - pack speed descending is one of the big ones. There’s a difficult balance to be had between realism (almost every single race route in Zwift would finish with the peloton together and a sprint finish IRL, without 4-5 hours of attrition before hand ) and allowing for interesting racing dynamics, breaks and tactics.


Potato: Apple TV 4K
Trainer: Tacx Neo

Ive had a chance to ride with the revised Pack Dynamics Algorithm a few times now. I’ve spent the majority of time on Sand and Sequoias with the C bot (not halloween version).

Side to side hasn’t changed much for me but I don’t have steering so that may be why. The pack when large enough seems to get wider than normal with up to 10 riders side by side when in the C pack.

There seems to be a draft discrepancy if you’re caught off the back of the pack. Once you get to 1sec behind you’re long gone and need to push twice the power to get back on. With a clunky iOS potato it really means you need to be paying attetion or the pack has gone before you know it.

I have noticed groups of riders breaking away from the C-bot quite easily at the front of the pack after the Oasis. Normally the group reforms and then splits at the climb after the springs turnaround point. Now it seems to be that the group tends to stay together more easily on the climbs but splits easier on the decents. We all know that in IRL once youre on the draft going downhill it’s hard to lose the lead group.

I’ve managed to describe the following really badly: Uphill feels easier to stay with group AND downhills seems to split groups easier after the changes.

Visual description of the effort required to stay with the group from behind.

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Here’s some footage of different groups of the DADurday chase race. - Dirt Dadurday Chase Race - London Classique - YouTube

For the most part I found the pack to be smooth and the my position as given on the leaderboard was far less jumpy. Like others have mentioned it probably was a bit easier on the hills, although I’m not sure if that’s the nature of this style of race and not wanting to break up the pack early. Generally, it was difficult to tell if it was much easier in the pack.

I’m sure there’s some way to handle this.

For example, if I am approaching a rider and I keep on the power or increase it, it would seem likely I want to go past.

If I approach the same rider and ease off the power slightly, it’s likely I want to sit in.

The game could keep a rolling average of the power of the past 5 seconds or something, and if that’s going down then use the “sticky draft” logic. Else just let me ride on past without any treacle.


Definitely set for this coming Friday. A


I THINK this is a bug with Zwift Hacks. As the event is set (and has been for some time), set with Steering Mode ON. A


It is changed at ZwiftHacks now. It required a change in the list processing code to match how Zwift tags the steering events nowadays.


Thank you Jesper AND Thank You for Zwifthacks! I’m not sure I’d still be Zwifting without the ZH calender of events available. A very important part of Zwifting!