Pack Dynamics 4 (PD4) has been in development and testing since October 2022, and yesterday Zwift flipped the switch to take it live across the entire game.
What does this mean for Zwifters? Let’s dig in and find out…
The Need for Updated Pack Dynamics
When Zwift began working on PD4, they had these goals in mind (my comments in italics):
- Reduce pack speed somewhat for large packs
Everyone who races on Zwift knows the large packs move faster than they should, probably because of “churn” on the front (#5) which allows riders to continually slingshot through the draft and into the wind. PD4 should knock the speeds of large packs down just a bit (think 1-2kph).
- Make it less punishing if you’re dropped/easier to bridge back up
With packs moving at high speeds, it’s nearly impossible to catch back on if you’re dropped. PD4 makes it a bit easier by reducing the pack’s speed (#1) but it also appears Zwift has pulled some other trickery: making the pack’s draft “shadow” extend further behind the group (around 20 meters) before it begins to drop off quickly.
- Make breakaways have a slightly better chance of sticking if the attackers work well together
Again, just reducing the speed of the large packs (#1) helps this happen. Zwift may have also adjusted small group drafting parameters to give them a bit more advantage when working together.
- Reduce the number of bunch sprint finishes in races
This logically follows from #3 – if you give breakaways a better chance of sticking, you reduce the number of bunch sprint finishes.
- Reduce churn and rider movement in large packs
Reducing the forward/backward motion of riders in large packs makes the game look more realistic and reduces the front-of-the-pack churn that helped drive up pack speeds. The idea here is, you shouldn’t move around in the pack (forward or backward) a lot unless you’re changing your power output in order to do so.
Given the goals above, Zwift chose to modify the beloved supertuck in PD4, making it more realistic and in keeping with how we see it used in IRL races (before the UCI outlawed it, at least).
With PD4, the supertuck only kicks in if you are outside of a pack and not drafting. That means no more crazy-fast mobs of supertuckers chasing back attacks on descents. And in fact, it means breakaways have a much bigger advantage on descents than we’ve seen in the past!
Along with PD4’s new supertuck restrictions, the three previous requirements must also be met for the supertuck to activate:
- You must be traveling at least ~36MPH (~58km/hr)
- The gradient’s decline must be at least -3%
- Your power output must be below 11 watts
You may see your power number in the top-left flash red when riding in a group with PD4. The red indicates “autobraking” – the game client slightly slowing your rider as it attempts to predict your intent and keep you from moving forward in the pack when that’s not what you’re looking to do.
In practice, for me at least, the slowing hasn’t been noticeable and has, in fact, kept me where I want to be in the group.
Wrapping It Up
The truth is, going from PD3 to PD4 is a much less noticeable change than when we went from PD2 to PD3. And that’s not a bad thing – it means Zwift is getting closer and closer to the pack physics we all want.
If you don’t race, there’s even more chance you won’t notice the move to PD4. Racers will probably notice the lack of group supertucking quickly, and we can expect the number of breakaways to increase as riders learn they stand a better chance thanks to PD4.
Ultimately, PD4 should lead to more dynamic and realistic racing, so I give it a big thumbs up.
We plan to do some drafting tests with PD4, to see if it’s changed the numbers. Watch Zwift Insider for news on that front.
Zwift says PD4 shouldn’t change the speeds for solo riders, but we’re running a few tests just to confirm that. If things have changed, you’ll hear from us soon.
Questions or Comments?
I thought something was different in the race I did last night. It is VERY subtle, but noticeable if you race a lot. It’s still not close real life. It’s still seems to push you to the front and rotate you to the back of a group,
Most folks have a delay between power input to the pedals and power in the game. So most time we push ourselfs to the front by not reducing power a few seconds before you would do it if the the delay wasn’t there (like IRL where there is obviously no delay). I don’t mind the conveyer belt effect you mention, it’s probably hard to do better and IRL a lot of time if you are being passed it kind looks like that. Again, if you control well your delay you don’t necessarily go all the way to the back.
Thanks for pointing out the red Powernumber flashing was totally unclear to me what was happening!
agree, I half expected it to be a graphics bug
Same here. I though the gremlins were at work again seeing the power number flash red.
Super exciting I think – I have not tried the PD4 yet and have two questions :
1) Can you still attack away from the middle of the pack as today or do you as in real life need to “have space ahead of you in the road” to move forward to stop autobraking. If not do you risk being caught behind slower riders blocking the road even if you are pushing the watts?
2) Any idea how the benefit of supertucking solo compares to the benefit of the draft of being in a pack ?
You can still attack from the middle of the pack, sure.
For #2 – hard to say exactly, but 2 riders holding 300W were basically the same speed as a solo rider supertucking in this test: https://zwiftinsider.com/speed-tests-supertuck/
The pack will have to work to beat a supertucking solo rider. Coasting downhill won’t keep pace with the supertuck, that’s for sure.
I think I’m most excited about how this may play out with a solo rider chasing a pack downhill (as often happens to me after uphill points segments). If they can’t supertuck as a group away, but I can supertuck to close the gap (maybe to that place further back to which the pack draft now extends) I will have a better chance of making it.
> the supertuck only kicks in if you are outside of a pack
What’s the definition of “a pack” that’s used to determine this?
You can only supertuck if you aren’t receiving draft from another rider. So you are solo or at the front of the pack
I had the same question, Alan. Not sure! My guess is, just being on the front of a pack won’t be good enough. You’ll need to be clear of other riders before you can supertuck.
Nothing to do with “being clear of a pack” you just can’t super tuck if you’re receiving any draft.
So if a solo supertucking rider catches another rider, does it pop you out of your tuck for a bit?
The pre-requisite to supertuck is that you be receiving 0 draft, so the front riders in a pack can still supertuck, just not the 2nd row of riders and those further back. The way this was written is misleading commenters below into thinking you cannot supertuck in a pack, period.
I just shared it the way Zwift shared it with me. Haven’t been able to test it to see exactly how it works in recent weeks…
During the ToW stage I did today, I was passed down the Titans Grove KOM by someone in a supertuck. It caught me by surprise. Maybe we were a bit strung out as we had just crested from the Reverse side, but I felt like the rider had to be catching draft from myself and the guys around me.
That’s odd, when I was going down the Titan’s KoM in the Tour of Watopia today, I was alone (got dropped by my pack that was 30s ahead and the nearest rider was 10s behind). I hit 61 kph, got into the supertuck animation, but my speed dropped as if I wasn’t supertucking and I fell to 55 kph and out of the supertuck. All of this while on the -5% section of the descent. I’m 100 kg, so it’s not like I didn’t have momentum. That is very unusual for me in the old physics model. Strange that you… Read more »
But remember, supertucking in group rides is slower than supertucking in races! https://zwiftinsider.com/speed-tests-supertuck/
i supertucked and put a minute into another dude who rode at 2.5-3wpk down fox hill – which i though was odd, but amusing.
Regarding supertucking what constitutes a group, any size larger than one? While I understand the reasoning, I’m a bit disappointed because I liked using supertucking to catch a breather after an intense push up a climb and if we are talking realism it’s probably what I’d do in real life. The game will now have no places to coast unless you intentionally fall off the back.
I mean, you can still catch a breather.. but yeah, somebody (heavier riders come to mind) could take advantage of that on the descent. Seems reasonable to me!
Welcome to my world Neil! I’m 49kg and when the bigger riders go into a supertuck, I have to put out at least 3 w/kg to even keep up while they are coasting. Not sure any advantage I have on the climb is as big as the advantage of being able to stop pedaling for the entire downhill. I’ll be interested to see how this affects small riders.
From the description, it seems that lighter riders could stop the heavier riders from being able to supertuck if they hold their wheels on the descent.
This is not correct. The front riders of group can still supertuck, since they’re not receiving any draft benefit.
But you’d be hard pressed to bomb through groups
Are all races now using PD4 or is it a mix? If so how do we know which race has which?
All using PD4, as far as I can tell.
If we can get heavier riders to want to routinely compete on rides with hills, and lighter riders to want to routinely compete on pack-centric rides (and, ideally everyone to use their actual/realistic numbers and have some incentives to do so), that would be super-duper.
It sounds like this might actually do that!
frankly this make it sound like lightweight riders stand 0 chance on the descents vs a super-tucking heavyweight xD
Depends where you draw the borders around the situation I guess — lightweight rider could attack off the front of the pack on the flat now leading into the climb. Super tucking heavyweight would have to get there before the pack.
Having done a grand total of one ride on it so far.– think it’s very pro-breakaway and I found it easy to go off the front of a big pack which was never the case before.
From the description, it seems that lighter riders could stop the heavier riders from being able to supertuck if they hold their wheels (forming a pack) on the descent.
What about TTT? If the Team is using the Hybrid, will PD4 avoid going over the (higher power)lead while churning behind him? Thx
There’s no free speed using the churn in the hybrid. So likely proper paceline in a team that looks like a proper TTT
But good news is it is easier to position and stay in a wheel
But washing machine TTT days are over
I’m glad you said “look more realistic” instead of just realistic, because others calling this realistic..that’s just silly. This is certainly not realistic. Trying freewheeling in a PD4 blob, like you do in a real life group, and see how fast you get jettisoned straight out the back!
Zwift physics is a joke. They just keep piling hacks on top of hacks because the fundamental model is so flawed and unrealistic.
chill daddy… also why would you want to freewheel?
“autobraking” sounds kinda sus..
I don’t normally try breakaways, but given this change and the perfect course, I gave it a go today on the Muckle Yin…and it worked!
Hard to say how much PD4 helped, I’m guessing that it made all of the difference
Not sure this is all totally correct based on my following the PD4 dev thread. doubledraft is now the default, this is a big deal for small people supertuck only works if you are not in the draft. That is, it still works in a pack, but only if you are on the front you are autobraked in a few combinations of circumstances but the main one is that you are dropping off your power (that is, you indicate you are not trying to pull because your power is going down not up) and your draft is falling off (that… Read more »
I’m glad for number 2. I zoned for a second and lost contact with a robopacer group and no matter how hard I tried I couldn’t catch them.
When you see power number in red because of autobraking, does the number of watt still indicate your real wattage or is it modified due to the “braking” and actually you’re producing more watts?
The wattage is still the wattage you are actually putting out, it’s just a red flash to indicate the system has checked your speed by some unknown amount because (for various possible reasons) it inferred you did not *really* want to pull through, you were just churning up
Did they fix the companion app not connecting to the ride on current IOS with this update? I miss using the app during rides!
It’s working fine for me – far as I know this isn’t a widespread issue. My guess is it’s because your phone isn’t connected to the same local network as your Zwift device. Make sure it is – and if that doesn’t work, maybe disable cell service on the phone and/or make sure the phone isn’t set to use a cell signal if the internet connection isn’t good.
I believe the issue is your Wi-Fi option in IOS. Go to you settings, Wi-Fi click the i and then turn off private wifi address. This should solve the problem.you may have to restart the companion app.
How about fix the downhill penalty on light riders- in the real world- i coast by pedaling big boys and have zero problem easily staying with the big boys- on zwift i have to pedal harder downhill than up to try to stay with them- yes- my frontal resistance is a tiny bit of theirs… i can easily coast 60 mph by myself down a 4% grade in colorado- shoot- i cant pedal that in zwift- i can hold 45mph while standing up making myself a sail to slow down….
it seems for me even harder after today’s ride. I hade big oroblem stay in pack with disk even.
I love these changes. Should make the next ZRL more fun / realistic!
ZTO will be keen to see how it works during our Power Push Tuesday rides where we blatantly use the dynamic of a collective bunch to beat zwift dynamics and post fast times on Tempus Fugit
I hope the PD4 is better than what was in test for a while. It was terrible in testing, with the draft being basically non-existent anywhere but in the very front and it would often suck you into the front and you would have no draft at all and end up off the back sprinting to catch the pack. Fingers crossed it was improved before being released otherwise group rides are ruined. It was pretty close to universally hated in the groups I rode so hopefully it isn’t too bad now.
It’s dramatically better than it was back in 2022.
That puts my mind at ease because it was just terrible in testing. Thank you. Will wait and hold judgement until I can do some testing for myself. On a side note, I always find Zwift’s push for realism amusing considering there are dinosaurs in the game.
I made the same horrible experiences in some test rides and hope exactly the same that PD4 is much better now 🙏🏼. In theory, the thoughts and changes sound good, but only the practice will show us the truth … 🤷🏻♂️
It was exactly this terrible a couple weeks ago in test races. Highly doubt they fixed anything since then. Many people complaining about the absolute lack of drafting outside of the first few places and Zwift refuses to listen to everyones experiences.
That’s odd, because I’ve ridden recent PD4 races and that wasn’t my experience AT ALL.
And testing with Sauce would also indicate that’s not the experience at all. Plenty of draft to be had.
I felt the draft was just fine today. And not having to worry about churn was a welcome relief! I only went to the front when I wanted to.
Eric, do you think/know if Sauce is still able to calculate/show the correct PD4 draft effects ? … so without having an update depending the new draft physics ?
Sauce don’t calculate anything. It only shows the value that zwift game is using to do their internal math. Sauce will just keep showing the value.
sounds good Erick … so Sauce shows the correct PD4 draft effect numbers at once … that’s great … many thx
I rode for 2 hours with Yumi today and really noticed the change.
Far less churn and chaos in the pack, felt quite calm throughout the ride.
2 thumbs up.
The PD4 news was exciting for dudes in my race today who assumed that if they get a 4 second gap they could ride away like Wout and Laporte! So many breakaway attempts. What I noticed with the PD4 is that it is much easier to get a gap, but maintaining that gap is still a brutal ask.
I saw the same in the zRacing RGV race I did today. It was easy for a rider or two to get a small gap, but then we would still bring them back.
The difference was at the end when about a half dozen of us went off the front with about 1.5 miles to go. We worked well and three of us held off a hard charging pack to win the podium.
I was a victim of the PD4 experiment in the Tiny Races, and I’ve honestly had ptsd about it since. So wasn’t keen on trying it again. But I did today, and I agree it’s much better. It is actually subtle. I and three other riders put together a little breakaway way too early in a race. It wasn’t really intentional, just sort of riding our momentum after a sprint. But we gained ground on the pack and stayed away much longer than I expected. The rest of the race seemed about the same, maybe slightly less churning. All in… Read more »
Glad to hear it. I also had PTSD after testing last year. Ride On!
I wonder if the auto-braking will be expanded in the future, similar to RGT, where riders flying into turns are realistically speed-checked and any “extra” watts expended are shown as being wasted with a color change.
They’ve been working on that too. But wanted to do so separately.
I really dislike PD4. So, I‘m+-100kg heavy, almost 193cm and recently upgraded to B. E.g., I raced RGV, which is super flat in the beginning and should be doable to hang on because I can put out 320-340 watts on flat sections, yeah? I fell back to one of the last places in the pack and hell was it ridiculous. I pushed up the watts, did not move a bit forward, I fell back even more, so I sprinted into the group, paused a second to catch my breath and use the acceleration of the sprint, display started blinking red,… Read more »
I will agree that a lot of the tricks that us bigger guys used (I’m a couple kg less than you) no longer work. So much pushing really hard and then using the momentum to freewheel for a couple of seconds to catch my breath (or do the same over the top of a climb) seems out the window now. Will have to learn some new tricks, I guess.
dislike…in 2 fast rides last night our chase group (super B’s) was pretty big relative to the breakaway and we could not close the gap at all. Near the end, 1 person broke away and stayed at 10 second gap with a very modest 3.5w/kg effort. We had 6 chasers putting out 3.0+ w/kg and couldn’t close. I think zwift nerfed the pack advantage a bit too much
Why should 6 chasers putting out 3.0 be able to catch a solo rider doing 3.5?
If all of the 6 riders are putting out 3.0W/kg, they will be able to benefit from the draft of each other and should not have to put out the same W/kg as the single rider to go faster than him.
No? The pack only goes as fast as the front guy pulls… So 3.0 W/kg.
There definitely is a learning curve when it comes to the new Red Flashing braking system. In yesterday’s Cubble Crusher I was second wheel going into the sprint. I decreased my watts slightly to stay on the guys wheel in front of me. When I did, my watts flashed red and I was immediately rotated to the back of the sprint pack! Certainly cost me a chance at the podium! Certainly not realistic but then again, it is a video game 🙂.
Meanwhile the ridiculous linear height CdA penalty remains. Until zwift ditch that nobody is really going to take it too seriously. No amount of fettling with the drafting mechanics will address that elephant in the room. Combine that with the fact apparently w/kg has a bearing on your flat speed (eg 50kg rider 200w 4w/kg = 37.5kmh vs 100kg rider 200w 2w/kg = 32.8 km/h) and you are getting double dudded. Not sure why a climbing metric (w/kg) has any bearing on flat speed but hey thats how zwift rolls. Not sure what world 200w gets you 37.5 kmh on… Read more »
Flat road speed is affected by weight through the rolling resistance term of the equation of motion.
I feel like such a turn sprinting on a spin bike, wether it’s an advantage or not I feel it’s damn easy to manipulate the game
I felt hard to use steering after this update.
The line changing needs too big steering angle.
And the direction is hard to feel because my avatar tilt left and right towards the back of the screen (I want that the world rotates).
If possible, I want it back if possible before this update.