Dear Zwift HQ,
I’d really like you to continue to work to improve the in-game drafting physics.
And in particular to address what is colloquially known as the blob effect.
Specifically where a group of riders can achieve unrealistically high speeds in the draft, due to various factors. It’s fair to say, it is hard to know exactly what to change as I don’t know exactly what the in-game algorithm is for drafting, I only know the consequence of it, which is somewhat unrealtically high speed of larger groups of riders.
I *think* this happens due to some of these factors: the constant churn of the riders assumed to be at the front, the magnification of the draft benefit to large groups beyond that which would apply to a smaller number of riders and the easy pass through of riders. There may be other factors.
The *benefit* of addressing the blob effect, would be to reduce speeds of those blobs of riders, to somewhat more realistic levels. That would for example make it easier for riders dropped from a groups to catch back to the group, make it easier for riders to bridge between groups and in race situations make it easier for breakaways to be initiated and formed.
I recognise this would take some work and intended and as well as unintended consequences would need to be worked through. But I do feel it would improve Zwift for the reasons I mention above! 
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Isn’t the drafting in a large group realistic though? I personally think it’s spot on.
I think the speed is about right however what they could do is as large groups go around tight corners they slow down and go around slower than a smaller group or solo rider. This requires auto braking as myself and others have requested but in addition large groups slow down further because of the congestion. This then makes it easier for solo breakaways or getting back on after being dropped.
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Yes Nigel, agree on the braking.
On the blob effect, I do find the speed just seems several kph too high. I’ve been dropped by sub2 rides (whilst texting normally!) and then had to ride sustained 4 w/kg to get back onto the group rolling along at 35-40 kph… which it can do even at 2w/kg with a big group of hundred+ riders
In races similar thing, it is near impossible to break off the front of a group. That is never going to be easy, but the extra speed makes it harder. Or to bridge between groups.
I think the churn or riders at the front can cause a bit of a feedback loop which sustains speeds higher than in real world (where the front is very defined and riders behind have to make a very conscious move to move to the front).
The existence of the effect is well discussed in various forums, although I’m less clear what the change would be required is to fix it, I just hope Zwift HQ is continuing to think about in-game physics refinements!
I think by & large the effect is OK, however, on a couple of occasions when I’ve slowed down on a group ride to re-group, the group has shot past & I’ve been spat out the back & just unable to get back on, despite sustained efforts.
One gamification approach would be to introduce a one-shot “motor-pacer” boost avatar to allow dropped riders to get back onto the back of the pack. Every rider on a group ride would get this at the start & could use it to draw parallel with the ride leader if dropped.
Of course, always need to ponder the downsides - I’m sure this would start arguments about KoM’s, Strava Segments etc but I wonder if there is a way to make it work?
Haha, Chris I like it, like MarioCart Bullet Bill!! Great idea!
(Though, I’d still suggest that the reason that might be necessary is because the way a big group can draft can mean they can travel several kph too fast… which is what makes catching even a 2 w/kg group much harder in Zwift than in real life - at least that’s my experience, although I respect others may feel it differently)
Again I think the drafting adds to the realism. If you slip out the back of the back then yes it’s a hard task to get back in but it also works the other way in that if you try and go on a solo breakaway then the group effect soon pulls you back in.
This is the same compared to racing at every level.
For group rides provided you are not punching at your weight/slightly above it then you should be able to claw yourself back into the pack with a bit of 110% effort.
In a big peloton though, some riders have to be working hard to achieve the increase in speed. There is some small boost from the riders behind you, but overall the riders at the front work harder than those at the back. What seems odd in the Zwift case is that the group maintains a really high rate of speed despite the riders at the front doing relatively low wattage.
For instance, in a recent ride the Zwift mobile link dropped the sensor attachment (different issue) for about 15 seconds, and despite pulling a sustained 4-5 w/kg I was pulling basically no time back on the group in front which was doing 2.5. That doesn’t really seem to line up with my real life experience very well.