Pack Dynamics 4.1 - Test Events

That was suggested a couple times during PD4 development. The engine can’t deal with that very well right now, so 4.1 is an attempt to replicate those effects without actually moving you to the outside.

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I’ve tried a variety of surfaces over the years and am currently using some satin finish phenolic resin-coated marine ply directly beneath the Sterzo Smart. The heavy support itself holds fast to the rubber floor mat, and the Sterzo Smart can rotate on the smooth resin surface if really pushed, like you describe, but generally doesn’t budge significantly once I’m on the bike. I always centre the unweighted front wheel and the Sterzo Smart before getting on the bike, and then the friction seems to be enough to keep it in the same place throughout the ride. I use the steering every Zwift ride (10+ hours in the last week) and I haven’t had any occasion where it has moved off centre enough to affect use.
The centre-ing spring on mine is very stiff; I don’t know if more recent production models are different.
Admittedly, I’m no watt monster, so perhaps you and others are producing far more energy during big sprint efforts.
[Sorry for the off-topic tangent, everyone. It’s all grist to the pack dynamics mill in the end.]
Edit: spring=/=sprint

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That’s a shame because doing that, in addition to showing you that you’re not pushing hard enough to pass the front rider, would also decrease/remove the need for autobraking, slow people who just joined the pack from just rolling all the way through it, and allow people without steering some small control of their positioning (slow a touch, or at least don’t accelerate and those people moving forward will go outside of you, pushing you toward the middle). Seems like it’d solve a lot of the problems PD4 and PD4.1 are trying to solve.

I usually have a sauce window with custom data covering up the power display in the upper left, so I don’t see when I’m being autobraked. I know that’s a me problem, not a Zwift problem, but the whole autobraking thing seems so artificial if they could just decrease your draft by moving you so that you’re only partially in the draft cone as you move up.

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I weigh ~100kg, so it’s possible that my sprints are just making it move more - mine is on a rocker plate with non-slip microtextured surface, before that it was on a trainer mat that would get scrunched up on top of the carpet as the Sterzo turned.

I also don’t have the most solid of cores (something I was hoping the rocker would help me work on) and several people have noted in my streams that I look like my saddle is too high because I’m rock from side to side so much (even though the saddle is at the right height for my knees). Probably a combination of weak core and poor pedaling form as I grind at 70-75 rpm rather than spin at 90+ and compensate for the added torque by counterbalancing with my upper body.

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Another round of test events setup for next Tuesday. Configurations will be adjusted.

Same start times as this week. Course is 2 laps of Suki’s Playground in Makuri Islands.


Bumping this topic for visibility on the test events tomorrow :point_up:

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It’s a been a quite week in here :smiley:

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Didn’t do last weeks test, but we had no problems moving up in the group today. If i didn’t know this was a test i would have thought it was just a regular pd4 race, as i didn’t notice any different behaviour at all.

The A group was small with only around 18-20 riders, where regular pd4 are normally also okay, as it fails mostly in larger groups in my experience. So not really any positive or negative feedback i can give. We were able to get 4 men away, but think that would have happened in both pd3, pd4 and here, as it was a combination of the strongest and the people with high raw power to push the speed on flat.

Link to race video if someone else might be able to spot anything different


I also didn’t do the Test last week.

I did the first test this morning and have nothing exciting to report, all went as smooth as can be.
there was one flash of red as I got to the front just to stop me from hitting the wind and I found that helpful.

I did stream the race if you want to see me racing on the wrong bike. LOL

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I did do last weeks test as per my earlier post.

This weeks test ride was with a smaller pack than last weeks test. This most likely impacted how the race unfolded.

The first impression was that riding in the pace felt a lot like PD4. Compared to last weeks test it was much easier to maintain position and move around in the pack. After lap 1 a 4 man break was formed and they were able to maintain a 30 second gap. When following riders wheels trying to close gaps it actually felt easier maintaining the position behind the wheel in front.
In the chase group of 8 when the front rider pushed the pace at 5.0w/kg it was possible to sit at the back at 3.0w/kg. General feeling is that it felt easier sitting in the pack.

It will be interesting to hear what the feeling is like in a larger pack and with more attacks.


Did anyone noticed that you can’t pass a rider that is not drafting if your Net Power is lower?

I will do the test at 17:00UTC…looks like it’s gonna be fun

Today the test race was fine with PD 4.1 but a bit to easy to get through the group from behind.


Compared to last week it felt easier on the pack. Breakaways were almost impossible with the pack being to fast and recovering any gap very fast.
Last week had a better felling for racing.

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Agree with Diogo. I think the best solution is somewhere between last week and this week’s configuration (probably closer to last week if I had to choose?).

Good fun though!

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Definitely felt easier than last week and there was no braking or too light .Draft scale i think was the same as last week but without the braking so being in the draft was easier.Overtaking thing didnt felt like it was on so getting to the front didnt required any power at all. Breakaways were way harder because there was no needed power to get to the front and so there was a blob. So in my view in terms of drafting there is more draft at the back and there is more draft fall off than with current physics . In my opinion something with braking between last week and this week would be perfect

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I totally agree with the above Feedback.
We all did Pen B Race at 17:00UTC with 61 starters.

Moving up was really easy i also think it should be little harder passing riders in group at least in the front.
I also tested if i would be stoped when following a rider with no draft…it did work as it should IMO. Here’s is the stream Pack Dynamics v4.1 - Test Race (Phase 2) by VirtuSlo / Pen B - YouTube

The Route wasn’t the best for a good test because there is almost no FLAT. I would suggest Tick Tock, Magnificient 8 or Watopia Waistband for next test.

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i think that the best on the inicial tests is to do on every test on the same course to be consistent


i rode one, nothing weird as far as unexpected issues or game behaviour. in my humble opinion descents are still what is really killing breakaway attempts just like in pd4, 3, 2 etc, but i don’t know how i’d go about solving that.

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@James_Zwift can you repeat the fix from last week…we again have N/A Results

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Rode the same event as S_A above.

The fact that these are advertised as PD events makes breakaways a bit harder, I think, as participants know to close down attempts.

That said, I am loving the physics in general. I could see the pack having to work hard to close breaks, which adds a new dynamic to the game, knowing that I could help my team by making others suffer a bit to close gaps and maybe not push as hard on later climbs or sprints.

It was really motivating to see my solo break actually growing, until others sprinted up a climb and caught back on. Not claiming I would have made it all the way, but the physics felt right, as I was putting out a fair bit more power than the pack and the gap was steadily growing until the short climb.

Wish the results appeared, as I finally had a decent race.

After looking at some other posts, I suppose I do recall a handful of moments where I wanted to try a breakaway, but there was too much churn of fresh riders moving up from back of pack (around 8 of us toward the end), and I couldn’t quite assess when I, myself, would be able to launch my attempt from near the front. I had to kind of read the churn and attack once my position was optimal.