Pack Dynamics Test Events (December 2022)

There’s no reason why this shouldn’t be improved with PD4 too, if the churn is reduced. There’s already corner speed braking in the game that hasn’t been enabled yet.

I completely agree with you.

I’ll be happy to see an appreciable improvement. What is not clear is whether this would impact the dynamics outside of the bunch. The solo rider should not be caught as quickly by a heavier rider, mainly when additional power is being applied (if the lead rider is coasting, that is a different animal altogether). Braking in the corners will attenuate that in theory, but the impact, would that be proportional to rider size (reverse linear relationship) or fixed? The benefit might be minimal.

Honestly, I would be happy just to see terminal speeds for all riders ratcheted back on the descents. No one on Zwift competently descends at 80+ KPH - ON SWITCHBACKS! :joy:

Yes, it’s to stop any braking a bit faster. The intervals will be configurable so it’s not a big deal for now.


Before we look at descending issues, lets test it with this new formula for drafting. I have a feeling based on the above breakdown that we may see packs descending slower.
We need to test one iteration at a time, testing multiple new things at the same time makes it too hard to quantify accurately…


I popped another feature request up the other day that can also with help this…

FR: Only allow supertuck if there is no draft


A bigger reduction would not be enough according to initial tests, the amount of braking would be very mild in most situations and would barely make a difference. Anyway this value will be configurable so it’s not a big deal if initially is not perfect.

FTP or zFTP are not usable. The first can be manually set and the second can even not be available (e.g: someone that hasn’t ridden recently). So once and for all FTP and zFTP are not part of the equation.


I think it’s a fair statement to stagger out changes. I wasn’t suggesting it be addressed with PD4; however, I think addressing the physics model around group descending, unto itself is problematic. At a -8% grade, for example, the riders should be considered individually, not as a drafting pack. With the braking, I think Zwift might be backing into a stopgap, but it doesn’t address the root cause of the problem.

It’s been a very long time that this has plagued the platform. It seems like racing is the only mechanism to get positive change made, but I really believe this needs to be addressed more ground-up.

And I totally agree with you, as a lighter rider myself I too struggle a little on the descents, although not to the point that it’s an issue if I’m diligent. We need to balance that with the fact that lighter riders do have the advantage on the climbs so I’m OK with a little back and forth with difficulties up and down.

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Hold zFTP for long terms instead of expiring it. You’re ignoring an obvious and useful metric and ignoring useful feedback.

Then you need a better metric. 5% is noise.

I don’t understand this statement… can you explain how holding long term FTP fixes this?

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He said someone might not have ridden recently so they might not have a zFTP number. If someone hasn’t ridden in six months use their zFTP number from six months ago. It’s one person who might have a metric that’s off by a few watts, it won’t have any significant effect on a group.

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The 5% may sound like noise but only if you are comparing it to the previous power instead of the power you would need to maintain the same speed when your nose actually hits the wind (say 30–50% more depending on the speed).

How is it useful in the context of pack churn? My FTP is 300w, I can be riding in a pack at 200w. If I back off to 180w to avoid hitting the front, that’s a 10% reduction of my current output but only 6% of my FTP. How is that useful?

Edit: my quote on mobile didn’t work…

I said make the threshold 50% of zFTP. That would be 150w hard not relative numbers.

Absolute watts. Not reduction from previous X seconds.

So I have to back off from 200w to 50w before it would think I was reducing my power?

No. To 150w. Read what I wrote.

Alright, so im riding in a pack at 275w. I have to back off 125w before it thinks I’m easing? Pack churn is all about what’s going on now, not what I am capable of.

Yes. If I’m in the pack pushing at 300w and back off to 284w I am by no means trying to ease up. “Easing up” is absolutely based on what you are capable of. If you back off from 450w to 300w are you indicating that you’re trying to not pass anyone? Or are you just fading?