PD4.1 causes odd RoboPacer behavior [KNOWN ISSUE - FIX PENDING]


…and the new (corrected?) pack dynamics are now live:

As mentioned below, I’ve locked this thread and will re-open once the bug is corrected in a future game update.

Thread re-opened.

Since Pack Dynamics 4.1 launched, I find it much much more difficult to stay with the RoboPacers. (note: I’ve ridden several hundred kilometers with each of the Cat D pacers - others report similar with other levels, at weights above, below, and at the standard 75kg)

Biggest symptoms: staying in front of the bot seems easier while getting stuck behind results in needing MUCH more power to catch up or overtake.

PD4.1 may be more realistic, and appropriate for racing but whatever it’s doing seems at cross-purposes to a RoboPacer.

I really hope ZwiftHQ acknowledges and addresses this. Under PD4.1, I no longer look forward to RoboPacer rides and I don’t think I’m the only one. If there’s a way to revert ONLY the RoboPacers to PD4.0, perhaps that’s a solution since racers seem to like the newer pack dynamic.


Under Pack Dynamics 4.1, Robopacers surge ahead when reaching the base of a climb. (NOTE: other people have identified this as a long-standing issue in some locations but it seems to have been exacerbated under PD4.1)

I tested this by staying abeam or a meter ahead of pacer when approaching a climb, then applying 100+Watts more power and holding it through the climb. Pacer rapidly accelerates past entire pack.

See screenshot. Pay attention to W/kg on side. You can see other riders have increased Wattage to try to keep up - this is not just a “me problem”.

Observed this week with several Cat.D RoboPacers (D.Taylor, D.Bernie, D.Miguel).

My weight hasn’t changed appreciably in the last week, since the PD4.0 to 4.1 switch. (about 79kg)

While we were riding I also noticed that sometimes there was no draft, my avatar sometimes wouldn’t sit up while in the pack.

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That may be linked to your speed, I think.

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Above 50km/h your avatar is in drops and under 32km/h it will always be on hoods

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i can confirm this and since the beginning of the week i’ve heard from many friends - all of them riding with pace partners regularly - that they perceive the dynamics to be very different. the effort increased so much that several of them got discouraged and haven’t been riding with the bots for the rest of the week :pensive:

it got also very easy to pull the pace partner away from the group, so throughout the week there has been an endless amount of individuals deliberately opening gaps and dropping the group :man_facepalming: among the many, one zwift-verified account joined for just a few kilometers yesterday, opened almost a 10-second gap, and then left saying “hahaha”, forcing the rest of the group to chase…


If only the RPs were on TT bikes and didn’t get any draft…


I actually agree on this. It makes sense from a developer’s point of view that RPs should be able to draft just as all other persons. But being a RoboPacers comes with some responsibility (with great powers…) and if people expect a given pace it does not make sense to make it depend on where in the group the RP is…

If PD 4.1 is intentionally designed to lower pack speeds, shouldn’t we be accepting that? I mean, I love the extra miles I get from a pacer :slightly_smiling_face:. But if lower pack speeds are more realistic, I think that is a change we should accept, even if it’s hard.
As for the pacer shooting ahead, I didn’t notice that with Miguel on the Volcano ramp the other day. But I’ll look more. Maybe the game is thinking the pacers are in an “attacking” position and their CdA is bumped up. Then they shoot ahead relative to the pack because they were moving the same speed as everyone else and suddenly could go ahead easier. In my Miguel situations, Miguel seemed fairly inside the pack, so his CdA would be lower for the “high-draft situation”.


I’m pretty sure @James_Zwift said he tested this and reported that the pacer got dropped (presumably with PD3).

I have no issues with the slight reduction in overall pace. I could add on 2-3km at the end of that was an issue.

However, there’s definitely something odd with the new pack dynamics in larger groups. As a lighter rider, compared with previously when well-placed in the middle just behind the front of the pack, on flats I will drift to the back much more easily, and the effort required to come back through the pack is much harder and has to be sustained for much longer. Appreciate that uphills are where I can “catch up”, but again I feel it’s appreciably harder than PD4.

In larger groups, it’s almost as if the pacer is experiencing something different to the pack, and position in the pack is now much harder to achieve and maintain.


As a heavier rider (79kg), I notice exactly the same behaviour you described above.

That tracks.

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Okay, so it was speed.

Would also like to add that I had to coffee break and while doing so, speed downhill faster than D.Bernie losing a 2.5x mulitplier, which no big deal. Came back and I was 100m+passed the pace group stuck with a couple riders that rode ahead of the group… Is that suppose to happen, even though I CB in the pack with the RP?

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I think the CB only latches onto 1 rider – whoever you happen to be riding closest to? Not sure if you can CB onto a RP itself.

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There doesn’t seem to be any way to control it. I’ve had experiences where I started a coffee break inside the pack near the ride leader and was ridden out through the fence by whoever it attached to. I’ve also had the experience of having a rider use coffee break for me to sweep them back to the group and then when a rider passed me the coffee break rider appeared to switch to them instead. That was actually nice as a sweeper relay but I have no idea how it’s supposed to work or how you would manage it. It would be ideal to be able to pick a rider to attach to with the coffee break, so if for example you are riding with a friend but some stranger is passing you, you can be sure that you stay with the friend and not get dragged up the road.


I’m thinking the draft cone is having it effects on the pack. I rode with yumi for over 3 hours today (sisters course) and almost every instance on and entrance to a hill she would shoot up and out the front by a second or so. Then she would hit the wind and fall back to the back of the pack. It would take 3.5w/kg+ to keep with her at these times of surges. It didn’t matter if someone was in front of her or not. One time she was right beside in the middle of the pack and when the hill started she shot right to the front and was a second or so in front…


Looking back at the data of the exact course and PB, It is over 10 watts of more power to stay with the bot…

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The Pacer can’t get dropped from the Pacers group ride. Do you mean that some folk rode off the front?


I wasn’t there for the test so I’m not sure what I would make of it

I’m not positive, but I think the TT bike testing might have been before dynamic watts were begun.

The hill surging has been something I’ve noticed for a while, so pre-4.1. It is guaranteed to happen on this volcano circuit on the little hill just past the switchback. The pack usually surges forward going up the switchback, and the PP falls to the back. At the top of the switchback, the PP starts gaining momentum and racing back up through the pack, then just surges up and over the next little hill as though it doesn’t exist - usually flying past riders that ease up to let the PP catch up.

4.1, I’ve noticed difficulty hanging in the pack at a constant pace. I’m finding a lot more yo-yoing, and a higher overall effort/concentration needed to keeping from slipping off the back or surging through to the front. I attribute this change in my case to the increased difficulty needed to move forward in a pack and steeper draft fall off. If you get stuck on the back, there isn’t as much draft to pull you up compared to PD4, and a much more pronounced “stickiness” that holds your position back there. To move up, you have to break the stickiness, but if you over do it, you’ll move up to far/fast and slide up to the front and lose the draft again. Then the cycle repeats as you drop off to the back again. Zwift insider has a great write up on the wasted effort: https://zwiftinsider.com/road-bike-drafting-pd41/

Last thing I’ve noticed is the “narrower” cone means that it’s much easier to lose draft in 2nd or 3rd wheel off the front because there can be small gaps between riders spread across the road that “penetrate” deeper than before.

I hope these issues are something I can adjust to. There is so much unconscious feel and anticipation in Zwift pack riding that I usually notice subtle changes for a few days. But, the new “stickiness” results in much more wasted effort than before and isn’t as intuitive, so it will require more thinking and less feeling to master.

To me, the way to give breakaways a better chance is to fix descending, not nerf pack drafting.