New Pack Dynamics [February 2021]

Actually I’m not sure if the the problems I’m seeing are necessarily related to this update, as from my perspective the draft has been fundamentally broken already since the steering release, most recently demonstrated by a race yesterday on more or less the same roads as my earlier test event. (Mainly that blobs break up from within and it is somehow impossible to move into the gaps inside blobs even with red numbers, except on climbs.)

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Now that the make up events have finished, here is how you can access events that have the new AI (pack dynamics) enabled:

https://zwifthacks.com/app/events/

  • Click ‘filters’
  • Click ‘more filters’
  • Select ‘New AI’

I’m going to do the Crit City race tomorrow and record it. I’ll post a video with any interesting observations.

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@Mark_Cote can you confirm if the new pack dynamics were switched on for the ZHQ Crit City race 5pm UTC today? (Tuesday) I recorded it and will turn it in to an analysis vid, but I couldn’t really tell if it was switched on or not so don’t want to waste my time!

Hey James, yes the ZHQ Crit City races do have new pack dynamics enabled right now. Your event did have this on I believe.

Mark

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Thanks. I did a group ride today following the update (Herd: Bull run, 18:00 GMT), a few things I noticed below. I will aim to do a new video with a larger race field later this week:

  1. Riders moved more subtly from side to side versus before the update. That said, a lot of the movement didn’t really seem necessary when in the middle of a pack and not moving up or down. Is the side to side movement the riders adjusting on screen to match the server-side position?

  2. There is still quite a lot of riding through people. I assume for the most part this is as an alternative to braking when the width of the lane is taken up, however I have still seen it even when there are 2 riders in isolation.

  3. At the end of each lap, suddenly riders shot all over the screen and took up new positions. This only happened exactly as we passed underneath the lap banner.

  4. There doesn’t seem to be any improvement to the accelerating pack speed as far as I can tell. If you accelerate from the middle of the pack, you will overtake the front and the speed of the pack will increase even if you have backed off the power. In an ideal word, as soon as you end up alongside the front you will hit the wind and you will stop accelerating - so to pass the front, you need to be doing more power to overcome the wind resistance. It is therefore a deliberate and concerted effort to increase the speed of a pack. Ergo: This enables breakaways if the pack is lazy / not communicating

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I also entered The Herd Bull Run (https://zwiftpower.com/events.php?zid=1787374) today. It was tagged as “New AI” on ZwiftHacks and I wanted to see if there were any changes with the new update. I joined the D cat and it was sometimes hard to keep the pace (low enough).
I think riders sought the draft more than before, which resulted in tighter groups and more natural behavior. This is a good change and I enjoyed the pack dynamics now. It will be interesting to see how these changes work in a race with higher speed.
As James writes, what makes the field dynamics unnatural now, is that you will slide to the front of the pack very easily and speed up the group with little effort. I found it hard to draft now and still with some freewheeling, I would move to the front. I would expect to get more wind fast when I’m at the front and have to work to stay there. It is like the sticky draft is decreased now, which may or may not work well. I know this New AI is only about pack dynamics, so it could be just imagination. I don’t want Zwift to increase the CdA just because we can’t break to do positioning. I would like the CdA to be as natural as possible, so maybe the sticky draft has its place when it is tuned a bit more.

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@gloscherrybomb Will you be sharing the vid James now that Mark confirmed? I’m curious to see more vids of what people are talking about particularly with your followup observations you just posted.

I’m planning to do a new one later in the week. The crit basically had a group of 6 so there was very little to see - also yesterday’s update had some changes to the new pack dynamics so it wouldn’t really be relevant anyway.

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Good notes - I’ve passed along to the engineers to get some commentary. Appreciate this, sir!

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Hey Ole,

I spoke with the engineer on this project.

  1. Riders moved more subtly from side to side versus before the update. That said, a lot of the movement didn’t really seem necessary when in the middle of a pack and not moving up or down. Is the side to side movement the riders adjusting on screen to match the server-side position?
  1. There is still quite a lot of riding through people. I assume for the most part this is as an alternative to braking when the width of the lane is taken up, however I have still seen it even when there are 2 riders in isolation.

Both 1 & 2 are super complex bits of code. We’ve made great strides with this recent work but this is an ongoing workstream for our engineering team/

  1. At the end of each lap, suddenly riders shot all over the screen and took up new positions. This only happened exactly as we passed underneath the lap banner.

This is like a bug that was just fixed in development and will come in a future release. The intersection points of a looped road was causing avatars to go a bit crazy on the road.

  1. There doesn’t seem to be any improvement to the accelerating pack speed as far as I can tell. If you accelerate from the middle of the pack, you will overtake the front and the speed of the pack will increase even if you have backed off the power. In an ideal word, as soon as you end up alongside the front you will hit the wind and you will stop accelerating - so to pass the front, you need to be doing more power to overcome the wind resistance. It is therefore a deliberate and concerted effort to increase the speed of a pack. Ergo: This enables breakaways if the pack is lazy / not communicating

We haven’t touched this part of the code, so it is indeed the same as before.

Mark

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I’m glad you credited me with these notes, but they are actually @gloscherrybomb’s :slight_smile: Anyways, I’m glad you take our feedback seriously and take on his open attitude.
When you have this pack dynamics dialed in, you should definitely look into #4 and the drafting in general. The ride “feeling” can be a differentiator and an advantage if done right.

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Thanks for the prompt feedback Mark, much appreciated. Please let me know if there is any specific area they would like tested and I can focus on that.

Is point 4 in the longer term plans at all? This one could really make Zwift racing a lot more exciting.

Thanks

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Agree. 4 is actually very important for making big zwift races more interesting then they are today. Especially flat races at the top level are basically just races where everyone sits just under FTP until the last 2km where someone will win in a sprint. If done right, better pack dynamics can incentivize attacks and really spice up the racing. Will make for proper team racing aswell.

Really hope you look into #4 in the future😉

The team is constantly looking at our dynamics including drafting. This is also of course a super sensitive one to mess with as it “changes the rules of Zwift”. This is the team’s aperture, but no current defined goals or timeline to share right now.

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If you’re riding up legsnapper, it’s is incredibly frustrating doing the watts to catch up to to group ahead. Instead you are blocked by a group of people that can’t keep that pace. Race over.

This has made certain aspects of the game unplayable. It’s broken.

@Thomas_Hendry_R I have experienced this myself. It is really easy to get dropped when you are at the back of the field now. That creates gaps and everyone behind will have to sprint to get back. I find myself doing smaller sprints with 2W/kg extra to get back several times a race/ride now with New AI. Often with no notable acceleration in the group.
Another thing I have seen is that if I have been at the front and want to slide back, I will be pushed to the side of the group and have to do a sprint when I’m at the back to avoid getting dropped. You can say that this is like IRL, but I have not experienced this in my 200+ races with the normal pack dynamics. It could be that I’m not placed in the draft fast enough so that I take more wind than before.

I don’t have an issue with this if you have steering enabled, but if you have no say whatsoever over your left-right position, you shouldn’t be penalised.

Are we saying that sticky draft is more prevalent now? I have not noticed that myself.

My conclusion now is that the new AI has value in that it improves the consistency of the rider position - which may help TTTs and enable other improvements (like accurate race coverage, maybe even an elimination mode?) however it does not improve the way the pack works to improve the race experience, which is dependent on other adjustments such as point 4 above, speed around turns, etc.

Riders shooting forward randomly at every junction.

Easy to get dropped with this random “boost”. I haven’t seen it this clear, but this explains a lot :slight_smile: