Pack Dynamics v4.1 Speed Tests: 4-Rider Drafting with Road Bikes

After months of testing, this week Zwift rolled out their latest version of Pack Dynamics (v4.1) to all worlds. We’ve already summarized how PD4.1 differs from PD4 in this post, but now it’s time to measure those changes and learn how they affect the everyday Zwift experience!

Below you’ll find the results of our standard 4-rider drafting tests using PD4.1 and road bikes. We will follow up with a test using TT frames in a drafting TTT scenario, but we believe the same conclusions will be drawn from both sets of tests. Let’s dig in!

History of our 4-Rider Speed Tests

Our original TTT speed test post from 2020 gave team time trial riders some very welcome guidance about how to ride their races most efficiently. Then in 2021, Zwift rolled out Pack Dynamics 3, and we ran a second test to see what, if anything, had changed. (We found speeds hadn’t changed, it was just harder to hold an efficient single-file formation due the lack of sticky draft.)

In August 2022, Zwift+WTRL announced enhanced TTT features, including the ability for TT frames to draft in TTT events. So we ran our tests using TTT frames. Then several months later in April 2023, Zwift announced the rollout of Pack Dynamics 4 game-wide. So we ran our standard tests with PD4.

This week, Zwift rolled out Pack Dynamics 4.1 gamewide. You know what that means… time for more tests!

Test Goals

We set out to answer three questions with these tests:

  1. Is road bike power savings in the draft with Pack Dynamics v4.1 different than the savings with Pack Dynamics v4?
  2. Does Pack Dynamics v4.1 alter pack speeds, and if so, how?
  3. Are there any other observable differences between PD4 and PD4.1?

Test Parameters and Methodology

All test riders were set to 183cm height, 75kg weight, and rode Zwift Carbon road bike frames with Zwift 32mm carbon wheels.

Tests were done in an isolated event on Watopia’s Tempus Fugit route because it’s the flattest on Zwift and has a timed section (Fuego Flats Reverse, 7.1km long) which could be used to measure the speeds of each test formation precisely.

All tests were done with four riders.

Tests and Results

Test 1: the Churn

For our first test, we put all riders at the same 300W power setting. This resulted in a rather disorganized group of riders, but crucially, there was much less churn than with Pack Dynamics 4. The difference was so remarkable, in fact, that we made a quick video to show it:

Pack Dynamics 4.1 Road Bike TTT Test - No Churn!

The riders would often be 3-4 abreast across the road, with no rider taking the “pull” and no riders benefiting from a significant draft.

  • All riders @ 300W
  • Segment time 10:36.4
  • Speed: 40.19 kph

Segment time with Pack Dynamics v3 was 10:13.4, which dropped to 10:04.5 with Pack Dynamics v4. Pack Dynamics v4.1 makes a huge difference with this particular formation of riders, dropping the average speed by over 1.5 kph!


Test 2: Single File @300W

The second test had the lead rider holding 300W, with the other three riders in single file behind, holding the minimum wattage possible to stay in formation. This is what you would see in an outdoor team time trial:

  • Rider 1 @ 300W, Rider 2 @ 226W, Rider 3 @ 202W, Rider 4 @ 200W
  • Segment time: 10:36.3
  • Speed: 40.19 kph

Notes:

  • The “minimum wattages” stated for riders 2-4 on this test and other tests below should be considered approximations, as it is impossible to figure out the precise wattage required to hold formation due to Zwift’s dynamic physics engine and very small undulations in terrain, even on Fuego Flats.
  • Riders received power savings of 24.7%, 32.7%, and 33.3% – lower power savings than our PD4 tests, but still significantly higher than PD3.
  • As expected, the further back you are, the bigger the draft effect. But the additional draft benefit (only 0.6% more) for the 4th rider is less than we’ve seen with previous pack dynamics, which is a bit of a surprise.
  • In a TTT situation with all riders taking equal pulls on the front at these wattages, each rider would average 232W. (With PD4 the average was 225W, while PD3 was 246W.)
  • Crucially, test 2’s segment time perfectly matched test 1’s. That means the front rider set the speed of the pack in both tests, and there was no churn/slingshot effect unrealistically driving up the pack speed.
  • It’s worth noting here that we did a solo rider test at 300W steady, because we were curious if there was any advantage to the front rider if there were riders behind. There is not. Our solo rider turned in the same time as this 4-rider group.

Test 3: Single File @400W

This test was similar to Test 2, we just bumped the front rider up to 400W, then increased the power of the riders behind accordingly.

  • Rider 1 @ 400W, Rider 2 @ 308W, Rider 3 @ 268W, Rider 4 @ 258W
  • Segment time: 9:33.5
  • Speed: 44.53 kph

Notes:

  • Riders received power savings of 23%, 33%, and 35.5% (2nd, 3rd, and 4th rider, respectively). Very similar to the power savings seen in the 300W single file test.
  • Once again, the additional draft benefit (only 2.5% more) for the 4th rider is less than we’ve seen with previous pack dynamics.
  • In a TTT situation with all riders taking equal pulls on the front at these wattages, each rider would average 309W. (With PD4 the average was 302W, while PD3 was 326W.)

Test 4: Hybrid

Lastly, we tested a formation that many Zwift TTT teams have used, wherein there is one designated rider in front, and the riders behind simply churn in the front rider’s draft. This reduces the hassle of trying to maintain single-file positioning while receiving some of the benefits. But how does it impact efficiency?

  • Rider 1 @ 400W, Riders 2, 3, and 4 at @ 308W steady
  • Segment time: 9:33.4
  • Speed: 44.53 kph

Notes:

  • If there wasn’t at least 1 rider holding 308W or more in the pack of 3 behind the front rider, the pack of 3 would get dropped. (This number, not coincidentally, matches the wattage of the 2nd rider in the single file line of test 3.)
  • The pack of 3 did not benefit from the increased speed of the “churn” like they did with PD4. PD4 allowed three riders holding 273W to churn and sit on the front rider’s wheel, but here with PD4.1, if we required all 3 riders to hold the same power, it had to be 308W minimum to hold the wheel.
  • In a TTT situation with all riders taking equal pulls on the front, each rider would average 331W. (With PD4 the average was 305W, while PD3 was 335W).
  • The hybrid format was a solid option with PD4, but it is now terribly inefficient compared to single file formation in PD4.1.

Conclusions

Let’s answer the three questions we stated at the top of the page:

Is road bike power savings in the draft with Pack Dynamics v4.1 different than the savings with Pack Dyamics v4?

Absolutely! Here’s a table showing approximate power savings with PD3, PD4, and PD4.1 based on your position in a TTT group of 4 riders:

PositionPD3PD4PD4.1
217%28%24%
325%33%33%
430%37%34%

As you can see, the difference in savings between PD4 and PD4.1 is smaller than the difference between PD3 and PD4. Clearly, Zwift is dialing in their Pack Dynamics.

Does Pack Dynamics v4.1 alter pack speeds, and if so, how?

Our first test seeks to emulate the front of a hard-charging race, and that test returned a significantly slower result (1.5kph) with PD4.1. So yes, we can confidently say that PD4.1 slows overall pack speeds because it reduces the churn/slingshot effect that drove pack speeds up previously.

Are there any other observable differences between PD4 and PD4.1?

Yes. The four tests above showed marked differences from PD4 in two areas not already mentioned: the “shape” of the draft, and the potential for wasted watts.

Draft “Shape” Notes

Zwift altered the “shape” of the draft cone (the draft “shadow” behind each rider) with PD4.1. These changes could be clearly seen during our tests, in two ways:

  1. The cone’s “fall off” was faster. That is, riders lose the draft benefit sooner as they drift back and off the wheel of another rider. This may explain why the draft benefit for the 4th rider in our tests above was only slightly better than the 3rd rider’s.
  2. The cone is narrower. That means in a small group or single-file situation, left-right positioning is more crucial than ever. Steering may be beneficial here, but in a TTT without steering, teammates behind the front rider may need to make room so their friends can “slot in” and not waste watts sitting on the edge of the draft cone off to one side.

Wasted Watts Notes

What you don’t see above is something interesting we observed while wrangling our bots into single-file pacelines: PD4.1’s modified overtaking algorithm has, in some sense, created a new “sticky draft”.

In a single-file scenario like test 2 above, it’s now possible to have one rider (say, the 4th in the line) holding 30 more watts than the 3rd rider, without overtaking the 3rd rider. This wouldn’t have happened with PD4, but it definitely happens with PD4.1. It’s not the same as the old sticky draft, but the result is similar, if not more pronounced.

We assume this is due to whatever algorithms Zwift uses to reduce forward/backward movement in the pack. Especially in a single-file scenario, it now takes much more intentional ramping up of power to overtake the rider ahead, even if that rider isn’t the front rider in your group.

What does this mean for racers? It means PD4.1 makes it much easier to waste power in the pack. Similar to how the old sticky draft might have stuck you on someone’s wheel whether you’re doing 250W or 270W, you may now find yourself able to maintain a pack position whether you’re doing 300W or 340W!

So when you’re sitting in the pack, try easing off your power to see how it affects your position. Learning how to ride most efficiently with PD4.1 may take some trial-and-error practice, but you’ll probably find you can save watts by riding smarter.

Dynamic CdA Notes

While not a part of the tests above, PD4.1’s dynamic CdA changes are worth mentioning. Zwift tells us “the current setting in regular races give only a 3% benefit if your power goes above 20% or more of your last 10 sec. power.”

The goal here is to give a slight “boost” to attackers. Notably, though, dynamic CdA changes are not enabled for individual or team time trials, according to a knowledgeable source within Zwift.

What It Means for Road Racing

For road racers on Zwift (vs TT), we believe Zwift’s new pack dynamics will result in races that more closely reflect IRL racing in 3 ways:

  1. Pack speeds will be a bit lower;
  2. Breakaways will stand a better chance of staying away;
  3. Taking a pull on the front (and even simply moving forward/backward in the pack) will be a more purposeful action as opposed to an accident caused by the churn/slingshot effect.

Your Comments

Got comments or questions about Pack Dynamics v4.1? Share below!

Eric Schlange
Eric Schlangehttps://zwiftinsider.com
Eric runs Zwift Insider in the spare time he finds between riding his bike and managing various business interests. He lives in Northern California with his beautiful wife Monica. Follow on Strava

47 COMMENTS

Subscribe
Notify of
guest

47 Comments
Oldest
Newest Most Voted
Carsten Re. from Germany
Carsten Re. from Germany
3 years ago

Many thanks Eric for your hard work to show us these finetuned results. And a “well done” to ZHQ to deny the crazy churning at the front.
But two things are surprising. 1st ZHQ said, that it will be only harder to pass a rider at the front who has no draft, but with this new style of “sticky draft”, it also seems to be harder to pass a rider who is in a good draft position. 2nd ZHQ said, that the draft effect will be higher than before. These tests show a different picture. Perhaps it’s only higher in bigger packs ?

I see only one problem : in TTTs without steering, it could be difficult to find a good draft position because of the very narrow cone angle or draft shadow. But this we will notice better in personal future events.

Dave Sauce
Dave Sauce
3 years ago
Reply to  Eric Schlange

Would be very interested to note the draft effect down to pos 8 in an 8 rider TTT – we rode this morning and several riders noted it felt easier / needed less watts to ride in positions 3 and 4 than it did in positions 7 and 8 – which just seems odd, and maybe an effect of the modified draft cone.

Fons Beckers
Fons Beckers
2 years ago
Reply to  Eric Schlange

Agree, but like Carsten opinion, advantage new PD in TTT only “with” steering. Thanks Eric.

Harry Legs
Harry Legs
3 years ago

They’re doing some sort of check to see if your nose is in the wind, aren’t they. It’s becoming more dimensional (which makes sense given the steering).

It’ll be cool and stunning to start seeing simultaneous left side and right side ‘lead-out trains’ with a real gap in the middle. Not sure if we’re there yet but I’d love to see it tested.

Casey
Casey
3 years ago

On the Dynamic CDA comments. I had read somewhere that the changes in CDA would not occur on a TT bike in a TT or TTT. So you might want to check into that.

Wallace Harvey
Wallace Harvey
3 years ago

So far, I prefer the previous pack dynamics – especially when not using steering. There is so much extra and wasted effort required in the bunch now to maintain position or to move up in the pack or to overtake. I believe this needs to be tweaked further. Or, maybe consider one set of dynamics just for races and another more ‘relaxed’ set for group rides. I saw a lot more variability in my watt output just trying to do a simple robopacer ride at a steady zone 2 pace.

David
David
3 years ago
Reply to  Wallace Harvey

You are correct- there is a ton of wasted efforts with this new pd4.1-
it def needs to be tweaked further-
it appears they/Zwift just needs to make separate dynamics for races/ tts/ and group rides-

Alex
Alex
2 years ago
Reply to  Wallace Harvey

For me it’s the opposite – much prefer the new dynamics: it’s more realistic, much less churn & stickiness, and means if you have a gap the only way to get caught is for the chasers to put out more W rather than there just simply being more of them

4.1 is a big win for me

Wallace Harvey
Wallace Harvey
2 years ago
Reply to  Alex

In a racing situation I can understand this somewhat. But in a casual group dynamic it is a bit ridiculous the amount of effort you need to put in now to get back with the pack. If you are not careful, it is extremely easy now to drift back in the pack and getting back to your place in the group is much more difficult now – especially in large groups – like robopacers. I find it easier now for group rides to ignore or stay away from the larger groups and either ride solo or in smaller packs where I can achieve the same pace or higher with much less effort

Harry Legs
Harry Legs
2 years ago
Reply to  Wallace Harvey

Respect of the pack for the rest of the riders in the pack is a whole different can of worms. Riding solo feeling easier, for some packs, sounds true to life too tbh.

Alan Kudla
Alan Kudla
2 years ago
Reply to  Wallace Harvey

Agree completely. The first thing is that RoboPacers are around 1.1 mph slower with all the other problems enumerated above. The problems with narrowing the draft cone is not eliminated with steering. I have it and it can be very difficult to stay directly behind the lead rider. I frequently go back and forth several times trying to move as little as possible and end up over correcting. Why are they screwing with group and RoboPacer riders when trying to satisfy racers?

Carl
Carl
3 years ago

Interesting. I’m also 183cm but my weight is 95Kg and its pretty hard work out front and I can see why. Would love it if Zwift just added some numbers or a graph on screen to represent the draft numbers. As a newbie I find it hard to stay in touch with the rider in front of me to maintain a stable position. If say 35% from above is the best draft percentage you can get, then the graph would be at 100%. Cycling on your own the graph would drop to zero. Simple fast response bar graph would help would help you speed up or slow down sooner rather than waiting to see what your Avatar does. I find that Zwift is too laggy.

blah
blah
3 years ago
Reply to  Carl

sauce for zwift

Carl
Carl
3 years ago
Reply to  blah

No thanks, already looked at it, too much additional stuff I don’t want and don’t want to run another 3rd party App either. Screen already has too much unwanted stuff on it, much of what is already there wants to be “Optional”. Once you also run the companion App, all you want on the big screen is bikes and scenery and the important stuff .I want power, heartrate, gradient and draft.

Darin Boyd
Darin Boyd
3 years ago
Reply to  Carl

you can customize sauce to no end, and literally have only the draft figure on screen if you want. really easy and minimal cost, I can’t imagine not having it now I’ve used it for a few months. but you do you!

Wallace Harvey
Wallace Harvey
3 years ago
Reply to  Darin Boyd

Some of the Sauce for Zwift features should be incorporated into Zwift as part of the standard offering – just made optional for those who don’t want or need them. In particular, the visual indicator for draft level would really be helpful now with these new pack dynamics. Also, Sauce for Zwift doesn’t work across all platforms – namely Apple TV.

Wallace Harvey
Wallace Harvey
3 years ago
Reply to  Carl

Sauce for Zwift should make the additional screens ‘optional’. I for one wish there was a way to visually see how much draft your are getting in real time – especially now with these new pack dynamics. Without it, the system is too laggy for effective responses especially in racing situations.

Mike
Mike
3 years ago
Reply to  blah

Everything Sauce does should be built into Zwift.

Carl
Carl
3 years ago
Reply to  Mike

I don’t think so. I have been using Zwift for about a year and its only lacking a couple of things. The auto camera change is a no brainer and I have to run a free 3rd party script and remember to start it every ride. All it does is move through the 9 camera angles automatically every 15 seconds. The display of the “Draft” that Zwift is already using in the draft dynamics is another no brainer. All these things should be in the settings to be able to turn them on and off. I would get rid of the entire “Riders near you” on the right hand side of the screen as well for pacer rides.

Holly Brow -Williams
Holly Brow -Williams
3 years ago

Thank you Eric! Do you have a sense from this testing whether the new pack dynamics will make it harder for a petite rider (I am 162cm and 59kg) to stay in the draft? I already find that hard at higher paces if the yellow beacon is significantly taller and heavier than me, and dread finding it’s now worse!

David
David
3 years ago

It’s def gonna be worse for you – 🙁

Harry Legs
Harry Legs
3 years ago
Reply to  David

I haven’t tested it extensively yet but it doesn’t sound definite at all. Pack going slower and slingshotting less should make some riders more comfortable staying in.

If you can hold SOME level of power you should be able to stay in if that level of power is enough for the pack you’re in. We might see a lot more smaller packs, although it’s hard to say from Eric’s tests what will happen when the road is full and beyond the first couple of riders if it plateaus or drops off steadily or abruptly.

Sounds to me like being in the pack near the middle or front will be much less surgy. Eric was running bots which is an extreme example of this but a lot of humans like/expect to find a pack at a constant-ish power and hold on which previous PD weren’t really great at (leading to even more surges than strictly necessary as people tried to compensate!)

Darin Boyd
Darin Boyd
3 years ago

I was wondering last night if this had been rolled out (hadn’t seen a post on it) because the Coco group seemed significantly slower than “normal”. Even with a rather large group the speed on the flats was often as low as 37kph. It seemed worst in the dirt and broken pavement sections around the volcano, so I was wondering if they updated the rolling resistance on those surfaces (that have previously been the same as pavement if I’m not mistaken)

Nick K
Nick K
3 years ago
Reply to  Darin Boyd

Yes, I noticed this drop in pace for the Coco Volcano circuit. 3 full laps in the pack was 36.9 kmh this week, but was 39.7 kmh for the same circuit and distance in April. The size of the group can make a bit of difference, but not that much! My 50 km zone 2 session has gained a few minutes (it was also 177 Watts average this week, cf 185 in April for the same distance)

Yousif
Yousif
3 years ago

Im curious how long the reduced cda when attacking, is it only for 10 seconds or the entire time you are holding that higher power?

Fabian
Fabian
3 years ago
Reply to  Yousif

My question too. I assume it might be just naturally resolved when the >=20% higher power numbers gradually slip more and more into your average of 10sec-window; thus, increasing the avg and thus you would further need to step up your current power in order to stay >=20% on top of the increased avg power. But that’s just a speculation and I’m keen to see the facts.
Also, I have no idea how much -3% of CdA is worth?!

anthony peruzzo
anthony peruzzo
3 years ago

thanks for the post Eric. I can definitely tell a difference in racing and in joining the robo pacers. much slower speeds. In my race my average power was way less than almost every rider, even those behind me. I came in 9th out of 25, averaging 2.8 w/k. Just about every other rider was 2.9 or higher. I thought, how is this possible, until I read about the wasted energy you mention within the pack. Looks like I may have been the most efficient!

Stu
Stu
3 years ago

I had a crack at a race last night and thought I would try test out the differences. Here is what I found.

Warm up with pace partner.. I found it was harder to stay at the back of the bunch as I had to keep watts/wpkg closer to the pace partner than I had previously.

In the race (France/Petit KOM circuit – All Grades Combined), I managed to break away off the front of the bunch early on and held a 10sec gap by just watching the wpkg of the leaders of the bunch. It was much much easier to stay out front, where under 4.0 you would have to hold 5wpkg to hold a small gap with the bunch just so much faster even with less wpkg being pushed. Obviously the churn doing that. Then I got bridged to by 3 other riders (2 x A Grade and another B Grade) and we basically stayed away. The A graders attacked before the Cobble Sprint and they were gone for good but me and the other B Grader managed to hold the bunch until the Petit KOM.

Overall, the lap time was significantly down on PD4.0 (so Strava records there to stay unless they reset them). The race lap was 3 mins slower.

Before breaking away, riding in bunch was, I would say, easier to maintain position but harder to move up. I found that I had to hold higher watts to stay put, rather than sandbagging on the back, which was harder.

If they want to improve something, I feel like they should make it much easier to sit on the back of a bunch, like IRL. Something like half the watts of the rider on the front.

All in all, I think it’s an improvement and more realistic and made for better racing. No longer do you have to put out 5wpkg to stay off the front.
Happy days

Carl
Carl
2 years ago

I don’t know what else they have changed but for a 95kg rider it seems to be way better. I no longer need to pump 320W to stay out front on a 2.6Wkg C Coco ride and for the first time ever I managed to do 15Km over 30M out front of the pack instead of a few hundred meters. 256W average for the ride. Also seemed much easier to ride the wheel of a person in front of me.

Patrick
Patrick
2 years ago
Reply to  Carl

It’s better, but still disadvantages larger riders compared to real life. As far as I know, Zwift still assigns higher rolling resistance to larger riders.

If Zwift displayed Watts rather than W/kg, the disadvantages would be more obvious. Displaying W/kg, incorrectly implies that riders with equal W/kg should go the same speed.

Carl
Carl
2 years ago
Reply to  Patrick

I think the heavier rider while in the pack and riding on the flat really shouldn’t be penalised. The difference in aero must be minimal. Going up a hill, sure and that’s really noticeable and you get pinged, fair enough because the heavier rider has a clear advantage on the downhill but I’m not sure it makes up for the uphill.

James
James
2 years ago

Many thanks Eric, guess we need to get some race practice in ahead of ZRL otherwise we’ll be dropped! Oh wait, I get dropped anyway so no change for me, I’ll just get dropped quicker I guess!

Dan
Dan
2 years ago

Hi Eric.
I did my own group ride and race test of PD4.1 The group ride was the Asia 130 with approx 200 riders and I found I averaged approx 30 watts more for the duration of the event. That’s a massive increase over the duration of a 130 km ride (some 3 hours). All this sitting in the pack and not making any additional effort. This event is a ride, NOT a race and my goal was endurance training. So for those unclear on what ‘endurance’ means, in the most simplistic explanation is, riding at a Hear Rate in Zone 2 (60-70% of your max HR) for the entire ride. As soon as you increase out of Zone 2, you’re not training your endurance any more. So long story short, if you want to get some proper structured training done on Zwift, PD4.1 is not an improvement and is actually detrimental to the concept of group riding because sitting in a pack now requires more power.
I then raced the Glasgow Crit Course with PD4.1 and the constant pressure needed on the pedals to stay in the pack was highly noticeable. Your stats indicating a 34% saving with PD4.1 might be accurate in a fully controlled environment, but not in a proper race. What eventuated was essentially a time trial. That’s the best way to describe what PD4.1 feels like. Every rider had to sit near their threshold just to stay in the front. Seven of us made the front pack with the remaining 20 or so riders getting dropped with absolutely no chance to get back up to the front because they were already gassed, let alone capable of putting out extra watts to chase us down. Which of those 20 riders will come back and try again on Zwift PD4.1? Mmm, maybe, but who wants to get their ass kicked like that every race?
I’ve done over 100 TTT on WTRL and over 500 scratch races, and PD4.1 is only good if you have genuine time trial physiology, which 99% of us do not, even if we think we do.
The harsh reality is that PD4.1 takes the fun and tactics out of races, because it’s simply too hard on everyone, rather than just hard on the person that chooses to be at the front of the pack. I’ve also raced IRL for over 20 years and won my fair share, but never had to ride as hard as PD4.1 while in the middle of a pack.
If I want to do a TT, I’ll join a specific TT race, but for everything else I don’t want racing to be so one dimensional as PD4.1 has now made it. Not every workout (race or ride) should turn into a max effort, with an all out chest pain, legs deadened effort. That’s simply not a smart training method, nor is it actually good for you in the long run.

Harry Legs
Harry Legs
2 years ago
Reply to  Dan

For me 30W more is basically nothing at 120-150 even for 3hrs, feelable at 200-230, and starts to be a real ask at 300+.

If the biggest complaint about PD4.1 is that staying with the pack you want to or holding steady power consistent with that pack is too difficult (or puts you outside the zone you intend your session to be in to reach your goal), then I think that’s not really a substantive complaint about PD4.1.

Personally I’m ok with it requiring adjustment in selection of group and ride levels and I’m ok with artificially fast Strava segment PBs not going to be reachable with PD4.1.

Dan
Dan
2 years ago
Reply to  Eric Schlange

Eric, I did a ride with Miguel today on Volcano Circuit. The ride was 1kmph slower than the exact same distance in June.

Wallace Harvey
Wallace Harvey
2 years ago
Reply to  Dan

Absolutely spot on …

Todd
Todd
9 months ago
Reply to  Dan

I’m new here to Zwift (going on 5 weeks now) and just slowly pouring through all the data that Eric has amassed. I could certainly be missing something here but I’m not impressed with with the pack draft dynamic. I didn’t experience 4.0 obviously and that dynamic doesn’t sound good, but with the current dynamic they appear to have some serious issues imho… I hadn’t even read this until today but was pissing and moaning about the pack dynamic the other day when riding with Maria. I rode 66 miles on the volcano circuit with Maria at 2.2 w/kg. I’ve raced back in the day but took some time off and now getting back in shape, but I found the Maria pace to be comfortable group to hang (not hard but not easy). I could have gone longer but after 66 miles I was happy to get off the bike for a while (I did take a coffee a couple of times which helped me make the duration).

However, what I noticed/observed was that the power output once you were behind the Maria required nearly 100% the same power and if you fell behind to many positions the power output got higher and higher to remain in the same position. It seems that there are 2 issues. For reference because I expect it matters my weight/height is (197lb/89kg and 6’3″/188cm).

  1. the sticky draft is not realistic, requiring to much power to break free from unless you steer out of it.
  2. There were cases where I think Maria was pulled by the draft and pushed the pace higher over taking the front of the pack pushing around the 2.2 w/kg.
  3. If at or near the back of the pack I think some riders having potentially a hard time keep pack or lag in their system would start to slip off the pace and had to work harder to get through or around them to keep in the draft.

For example I experienced multiple instances where Maria would pass me (usually on a descent or in the flat after a decent) and I had to go from 2.1 – 2.2 in the pack and push 2.9 or higher to not be swallowed up by the pack. If I held 2.5 or 2.7 I would still get swallowed up and possibly passed by the entire pack. This might be due to some lagging response in game to power applied I suppose. I also found that the draft was much more realized while towards the front of the pack. Once you get back towards the back half or further the effect of the draft seemed to lessen and required more energy with less relief than in the front (top 5) of the pack. Eric’s video even showed that as he picked up the power by 20-30 watts the bot slid back and it wasn’t until the 40 watts was reached that the pressure to break that sticky draft was released. Once you break the sticky draft then moving up seems to require less power, but it felt like you had to punch it to break the draft and then back off some so you didn’t go flying off the front.

What I also think I found was if I just steered out of the draft it was easier to just move up in the pack. I didn’t measure it but I think it took about half the additional effort.. in fact if I just moved/steer out of the draft I could back off and roughly drop the power to 2.2 w/kg to stay in roughly the same position in the pack. This does kind of relate to real world I suppose because you can’t simply ride through people in the real world. but with out steering even if you were on the outer edge of the group breaking that sticky draft was not trivial.

Bottom line I just pressed to stay at the front of the pack as much as possible and found the effort significantly easier than it would be mid pack or even harder at the back. Once there it felt much like a typical draft on the bike in the real world. Even still there were times when the pack would simply swallow you up but it seemed to take less power to just break the sticky draft there than it would be toward mid pack.

Velolion
Velolion
2 years ago

I’ve done I think four 1-1.5 hour-long races now with PD4.1. I really dug it the first time as I’m an aggressive racer and was able to successfully execute bridges to groups up the road a few times that I don’t think would’ve been successful under PD4.

But I’ve since changed my mind and at this point pretty much really, REALLY don’t like PD4.1. I mostly race the Chasing Tour races and those events often break apart pretty early, so I find myself in smaller groups of 6-10 quite often. Here’s what I keep experiencing:

  1. I (and other riders) are constantly pushed to the lateral fringes of the groups and hung out to dry there without a draft — we don’t get auto steered in to riders’ drafts. The effects of this appear to only exacerbated by the narrowed 4.1 draft cone.
  2. Trying to execute a smooth rolling pace line, or even moving to the front to take a pull, is next to impossible. Through a few decades of racing and group training being smooth and not surging when rotating pulls has been beaten into my head, and it’s effectively impossible at the front of a group now. In fact I often get stuck behind the lead rider and the *only* way to get in front of them is to do a mini sprint, which invariably shoots me off the front. This experience is very much NOT like real life pack riding.
  3. I often find myself gapped by a half to one bike length at the back of the group, getting “close the gap” popups. I then try to gradually increase my power to close the gap and NOTHING happens until, all of a sudden, my avatar shoots forward and off the front.
  4. I even find that when I get right on a rider’s wheel I get the “close the gap” popup, as if the system doesn’t even see that rider, and maybe is cueing my draft off the rider two in front of me or something, despite me being laterally positioned directly behind the rider right in front of me and basically so close I’m about to clip their rear wheel. This may even been what’s causing #3, I dunno?
  5. Because I’m not a big guy (175 cm, 69 kg) with not ginormous power, throughout my career I’ve needed to pay a lot of attention to my pack positioning, particularly approaching critical sections of courses. I find it nearly impossible to reposition myself within the pack (and this has applied to larger groups, too) with any sort of finesse and accuracy…any modest adjustments I make to my power, like I’d normally do to smoothly move inside the group, net zero response at all from my avatar, until again I finally add so much additional power or decrease it so much that I shoot to the front or fall all the way to the back. The front and back are basically the two positions I generally find myself in, even though I’m trying to position myself strategically inside the pack.
  6. I have often found myself chasing down a group, putting out ~2 W/kg more than the riders at the back of that group (the only ones I can see on my interface) and closing rapidly, and despite that speed differential the moment I get within a couple bike lengths of the back of the group my speed all of a sudden stalls out, like I’ve hit some kind-of invisible wall. This has happened to me basically every time I’ve bridged up to groups, and the only solution I’ve found is that once I get within a couple bike lengths of the back of the pack and my speed starts to stall I then have to stand up and put out another big surge of power to break though the invisible barrier. This invariably accelerates and shoots me through the group and off the front, and is a very similar experience to #3 above. This is very, very much not like real riding, where when you’re closing on a group from behind you generally actually soft pedal or even coast, as you captured by their draft, in order to keep from slamming into the back of the riders at the rear.
  7. A few times I’ve even been closing on the back of the pack (whether that be from bridging up or being gapped off the back, like seems to happen often with PD4.1) and even though I’m laterally positioned directly behind the rider I’m closing on, the first “close the gap” notification I’ll get is the 2m one…it counts backwards to 3m, 4m, and 5m even though I’m very clearly closing up on the rider. So something makes me think in these cases that the system thinks I’m getting *farther* away from the back of the pack, and losing draft, when I’m in fact closing and damned well nearly on top of them. Maybe that’s why I feel there’s some sort-of invisible barrier I need to slam through whenever I’m just a very short gap off the back of a group?
  8. When I often find myself at the back of the groups I’m having to constantly stare at the rider list to monitor my W/kg vs the riders’ W/kg right in front of me, instead of being able to just organically and naturally maintain my position as I would on the road and have always done in the past on Zwift. Again, I think this is likely related to #3 above, but in any case having to stare at scrolling numbers listed on the right side of my screen is hardly what I consider to be a enjoyable, organic experience.
  9. I feel the speed advantage of groups, with respect to solo riders, has been diminished *too* much. I know Zwift never claims to be a simulation — it rather always claims to be “just a game” — but physics and the such greatly favor the speed of packs over individuals in real life cycling, which is why individual or small group breakaways are rarely successful in IRL races on flat courses, and why the key moves in IRL races nearly always happen on sloped roads (either up or down). I understand that the platform being *too* realistic along these lines could likely bore a lot of riders/racers, but I think they’ve swung the pendulum a little too far in the other direction.

So, basically, I think PD4.1 lacks any semblance to real riding and real pack dynamics, and pretty much blows. 🙂

Fons Beckers
Fons Beckers
2 years ago

Reading this about the rider in position 4 doing surprisingly worse then before this new Pack, this could explain my feeling in a TTT race with 3 other riders. I was the only one without a steer, and i felt like i had to work harder then doing leads. I’m also convinced that the 3 steering mates are riding a different line and going in 4th position, it was very hard to grab the wheel of P3 because i couldn’t steer to P3. Now i have to find out: 1. Was the new PD4.1 responsible? 2. Was (not having) the steer responsible? 3. Were both responsible? 4. Did i just had a bad day? Thanks

LUIS
LUIS
2 years ago

HATE, HATE, HATE!!!! THE NEW STICKY DRAFT – PD4.1!!! HATE IT!!! TO THE POINT OF LOOKING AT OTHER APPS…DESTROYS PR/STRAVA IMPROVEMENT! HATA OT HATE IT HATE IT!!!

R Jensen
R Jensen
2 years ago

@Eric Schlange does rider height in the TTT order affect draft? E.g. will the rider in position 2 get more draft from a taller rider in position 1 than from a shorter rider, or does it not make any difference?

Get Started on Zwift

Newest Featured Posts

Support This Site

Write a post, shop through us, donate or advertise. Learn more

NEWSLETTER SIGNUP

Zwift tips and news every 2 weeks! Click to subscribe.

More Posts