I’ll admit I’m not really clued up on all of this, I just know if you grab someones wheel you can draft them as they are punching a hole in the air, so how would someone in the middle of a pack applying the draft assist power up affect all this?
I’m just going to put this out there, was there any explanation on how PD 1,2 or 3 worked. It also had braking it also had a bunch of conditions that needed to be met to slow the rider.
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If you count reduced draft as “braking” sure, other pack dynamics had a similar effect on speed when your draft was reduced. But PD4 does something entirely different IN ADDITION TO slowing down when you are in a low draft situation: It reduces your speed intentionally and instantaneously when you are going marginally faster than the rider in front of you (within 3kmh I think) and reduce your power below 90% of your last 10 sec average power.
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I’m sure PD3 did have braking, I’ve seen riders drop 3km/h when they bumped into another one ahead.
Myself and @j4m1eb had fun tonight in a breakaway… it was 
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Time will tell.
Yes, it was called sticky draft and it existed since the dawn of Zwift. And this forum was littered with threads from people crying about it. It boggles my mind how the same people are now totally cool with auto braking 
Times change I guess.
Even after sticky draft went away, it still existed in some form by the looks of it, just wasn’t as aggressive.
You could blast apart the old Amelia groups why hitting someone with a well timed old style sticky draft then sprint away at full speed, especially if they were at the back.
I further postulated the Zwift auto-braking/collisions and drafting mechanics. I outlined above that position needs to be addressed, and I recognize this goal needs to be attainable and realistic. Just as it would abide by the S.M.A.R.T. principle.
This was further compounded Tuesday while riding in the Yumi group, when I observed my avatar gaining momentum at random — and thus, speed — starting from mid-pack and thrusting to the front. I was pretty steady of 3 W/kg ± 0.2 (about 215W). The alarming thing here is my power was steady, so intuitively, my avatar should have been near or on the front from the onset. If I were within the peloton, my avatar would have drifted forward to a position that necessitated my constant power with subtle momentum gain thereafter. Unless riders behind me spiked or surged their power for a short moment that easily exceeded my output.
The lead riders of the Yumi group still managed to keep the group tempo to 40-41 KPH on the flat at around 3W/kg. How are we gaining free speed at lower watt expenditure than Zwift solo rides and IRL? This is opposite of intuitive.
A final remark is that a blob of 50 riders should not be condensed in a 5 to 10 meter length of road, especially when said width of road could only support 4 or 5-wide i.e. riders abreast.
Perhaps a feasible course of action:
- Salvage the auto-braking framework/architecture that was developed in earlier iterations of PD 4.0.
- Remove ANY group speed ‘buffs’ (boosts) or weighed speed coefficients.
- Revise the draft such that more logic is applied when conditions are met. Also, overhaul the draft savings such that it matches to the peloton draft graphics users have uploaded
a. Gather and study those graphics. Establish code that relates position to potential draft savings by applying features that follow. Pay special attention to required riders that position fore and aft of the individual rider assessed.
b. Assuming stricter collision framework established in (1), formulate logic formulas that determine size of peloton and draft savings as a function of your instantaneous position and amount of riders surrounding you. Specifically, the number of riders ahead and behind, within a defined radius, need to be determined for the purpose of analyzing the peloton composition. Is it a solo rider? Is it a grupetto? Is it the peloton? If no riders ahead, we can rationalize no draft savings. If, for example, we have 3 riders ahead of a 1 meter radius from the selected rider avatar, and we have 20+ riders behind this 1 meter radius, we can assume they are positioned near the front of this “peloton,” and hence, will receive a corresponding lesser draft savings. Conversely, if 20+ riders were ahead and only 3 trailed behind, draft savings would increase to the point of potential coasting.
c. You will reach a point of diminishing returns, a ‘limit’ for draft savings, relevant to riders ahead. This is the point no further code required and/or can be re-used if still more people behind. Because this code needs to be re-compiled instantaneously and for the entire peloton, one problem here is when attacks line out the field. What was once a homogenous blob becomes a strung out smattering of riders. Some clumped together and others gapped — the beginnings of grupettos. Auto-braking with smart, dynamic draft algorithms here can be the practical game-breaker resolution. - A hypothetical — what if someone wants to attack from within the peloton? Then a guy or two behind wants to net a “free” ride along? This is the tricky part about the collision mechanics. Perhaps people must learn either to be (i) on the front for attacking or (ii) drift all the way to the back and then accept their attack will go on outside lanes of group, essentially taking on greater drag. There could be some side-draft benefit — particularly if wind were included — but it doesn’t compare to the draft behind a rider.
Or don’t change anything because pd4 is really nice.
I did a lot of races, some riding with pace partners and today a 1h30 endurance club ride, all were perfect with pd4.
Why changing only for the sake of changing?
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They should be different things though. Sticky draft “trapped” you and held you back even if you were going faster or applying more power than the rider in front. With the new PD, that shouldn’t be happening (assuming I’ve understood the intention correctly).
My understanding was that it would only slow you down in the pack if you were doing lower power than the riders in front. If you increase power it should still allow you to move forwards.
If that’s not the case, then I’m sure the complaints will come (full disclosure: I don’t think I’ve ridden anything with PD4 enabled yet).
Or maybe it’s having the opposite of the intended effect. When I churn to the front now, instead of backing off I surge very slightly to make sure I still get overcome eventually but don’t get braked. Which, combined with 150% draft effect, will speed up packs.
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So you take a small turn… if you put more power it is normal for the pack to go faster. That’s what we want. With pd3 you wouldn’t do anything but still go faster… with pd4 you have to have a surge to accelerate the pack, and you have to do it intentionally.
That’s perfect.
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No it is not. Still suited to ‘blobby pelotons’ which is not applicable to IRL when the going gets tough
Ride in a sizeable enough (try 60+ riders) bunch on zwift and you will see insignificant differences to PD3.0.
And in what planet do you achieve 40kph on the flat at barely 200W pulling the group ride? You do not. Ever. Cycling is harder than that
You want this PD package strictly for social rides? Fine, but not for competition
I only do the slight surge after I’ve unintentionally drifted to the front and am already going to be overtaken, and only enough to keep from getting braked. It’s after I’ve been autochurned to the front, let off just slightly before hitting the wind, and bump it back. I’m working against the algorithm and the packs still go way too fast.
Doing the cobble crusher race this morning we were generally going 40kph for around 200w, and I spent a lot of time on the front at a relatively light effort for the speed.
[quote=“Daniel Jamrozik [+R], post:234, topic:605018, username:Daniel_Jamrozik”]
Ride in a sizeable enough (try 60+ riders) bunch on zwift and you will see insignificant differences to PD3.0.
And in what planet do you achieve 40kph on the flat at barely 200W pulling the group ride? You do not. Ever. Cycling is harder than that
[/quote]
If you read all the posts about pd4 you will find that I already posted a ride i did irl at 180w (177w in fact) for 39 km/h on 31 km, in a pack, but taking some pills (when I take a pull I am at 270w)…
So if irl it is possible (on flat, without wind, in a pack, and I am short and light), why wouldn’t it be on Zwift?
For your first comment, I just rode a 1h30 endurance ride with 350 person, but the small pack I was with was around 60 persons… but I didn’t need this ride as I see a lot of differences with pd3, I don’t understand why you are telling me that.
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[quote=“Daniel Jamrozik [+R], post:234, topic:605018, username:Daniel_Jamrozik”]
And in what planet do you achieve 40kph on the flat at barely 200W pulling the group ride? You do not. Ever. Cycling is harder than that
[/quote]
Here it is… this is an example. I have more rides like this.
Which pace partner did you ride with?
You’ve got a whole lot of people showing that Constance now is doing 48-50km/h alone with standard 4.2w/kg on the flat and everyone is having to launch 5.5w/kg or more to not be dropped. At certain points she zooms ahead.
IRL I am not doing 48-50km/h on the flat roads if I’m pushing 315w (same as Constance) even despite Cervelo S5 2020 (very fast bike) and very aero position on that bike and good conditions.
Come join the Constance group today and see how it is for you.
IRL best for me on my own was 35km/h average with 100km and 1000m+ (with a Giant TCR Advanced SL1 in hot but calm conditions). I doubt even in perfect conditions I’ll be anywhere near the fastest pace partner level of speed.
I’m 175cm and around 59-60kg.
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55kg, 168cm
But on a not so aero bike (canyon endurace)
This whole ride was 30 km solo and 70 in a pack (training ride, just turning on a bike track in Paris)
I very clearly italicized pulled when i specified “barely 200W.”
You never pull i.e. hit the wind dragging the group along at 40KPH without gapping them from your power input moments before. On the flat. Velocity/Speed is all about power input. Drafting is secondary; never free.
Of course it is possible to average below 200W at that speed using drafting. Your variability index will not be near 1.0, however
I am all supportive of sharing IRL data, so i credit you there! Feel free to discuss more 
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