Zwift drafting is broken

It seems like the category system is optimized for the typical mostly-flat races. Instead of allowing terrain to naturally select for the right type of rider, they put their thumb on the scale to make heavy riders competitive on routes where they would not be competitive IRL. I don’t know how intentional this was, just looking at the effect of the design. They try to “fix” it for light riders on flatter routes with the Watt floor but the result of these decisions is kind of arbitrary and packed with predictable unfair corner cases, like the scenario of two identically sized riders with zFTP 199W vs 200W being in different categories.

Here is a fair reference of what to expect as a lightweight going down the descents; these high spikes are ~600w actually.
Due to … me wanting some rest, but then falling too far back; and the inconsistencies in the descent angle, there’s no real way to safely sit behind a heavier rider.
The only parts I hit 0w for reference is the drop right before 35km, and the one near that 38km area. So being in draft, I wasn’t able to supertuck, but still getting dropped by a rider producing 0w ahead.

15kg isn’t that massive of a difference either; had the person in front of me been 20-25kg more? I would’ve been dropped, no questions asked.

HR graph left in for anyone curious; that’s me hovering and climbing above threshold HR, so in the climbing section, that’s only 3-4BPM up and down (aka… not very much at all). Before bottoming out at Z2 range there on the far right.

You really just have to pick your battles; or… in a case of a series like FRR, a long, exhausting series, know your limits and have a very solid understanding of zwift physics.

This is just the way it is, if you’re serious about racing in Zwift, it’s just something you have to learn and deal with!

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I have noticed in both group and bot rides if you use the coffee stop on steeper descents the rider pops out the back of the group. It has happened to several riders in group rides I sweep since at least v1.56. I assumed they pedaled and lost coffee stop in error. After seeing your post his morning I tried to use coffee break on the descent from jungle to watopia esses. I stayed in the group until the last part of descent where it hits -10% and I was spat out the back almost as if brakes were applied. Doesn’t answer the draft issues you have experienced though it may explain your comments about being dropped on epic downhill while using coffee break.




I’m a 75kg 170cm tall rider on Zwift Concept and this morning on the BMTR Short Adventure (D) ride in the midst of Red Beacon assignment issues in parallel, several of us had a “nerfed” pack dynamic where the best strategy for us was to eventually break off of the front so that we could ease to the group ride pace outside of the pack.

The group leader and many of the riders paced around 1.8-1.9 after our short warm up and some of us had to maintain 2.3-2.5 to hold the pace. While we were in the pack, it persisted, so our best strategy as I have found in the past is to break out of the pack so that we can ease to the pack pace. I have most commonly observed this issue when there are beacon assignment issues… Red Beacon assignments differ for other riders, or no Red Beacon assignment shows at all even though that rider is on the ride.

My power graph shows our slow roll out of the pen, then the struggle to keep in the path, and the eventual required break-off to stay just ahead of the pack to ease to pace.

My suspicion is some server synchronization issue.

To the development and server teams at Zwift: do your jobs.

I’m super confused.
You’re saying the event today; but the BMTR ride states it was in London; why are you showing images of the Tempus Fugit area?

There’s also some weird settings in the BMTR rides; as double draft appears to be set to enabled (does PD4.1.1 ignore that setting???). Because all the rides I join don’t appear to have double draft set; so maybe that’s a culprit to some of the issue?

Another potential settings wise is those rides don’t allow TT bikes; so it’s entirely possible folks were joining in on TT bikes, and were set to the Zwift Classic wheels/tires & frame.
For the record, the Classics are VERY slow; more than people realize. Easily 0.1-0.2w/kg slower than more aero wheels; and in a fast moving pack… probably upwards of 0.3w/kg for very lightweights.

That said; looking at the results… for London, everyone’s power in the D cat seems on point.

Talk to whoever sets up the BMTR rides and tell them to disable double draft, that might be part of the issue.
Second; remind folks to check their wheels, especially coming off TT frames, which some folks very well might be; and getting chucked onto the Classic wheels and frame; which absolutely will matter in this scenario.

B and C paces were in London.
D pace was on Watopia’s Waistband.

And that brings up another point. When joining such an event set up like that.
Always… Joining London for BMTR Short Adventure. Hang tight… changing worlds to Watopia…

Nobody in D should have been in London.

I was on Zwift Concept personally. I can’t speak for others. I didn’t see any TT bikes, however.

Oh man, that’s wonky! Guess when it’s set up as a race format I forgot you can do that.

I would still check and have that double-draft setting removed. I don’t… think it matters, but it’s an oddball one that could potentially be causing some grief.

Side note; I know you mentioned the red beacon troubles; if you saw my response in there; try having your red beacons joining in fairly late too (especially if you have a whole stack of them potentially). Either having them rejoin at the last second, or joining with a minute to go while most others are already in the pen seems like a temporary band-aid solution.

I don’t think this is wrong at all. Watch world tour racers in a pace line. When a rider finishes their pull and moves off to the side, they often get out of the saddle and crank to get back into draft in the back. This tells me they are putting out extra watts until they are back in the slipstream or else they would get dropped.

very normal, and no different in a real pace line if the speed is decent… the higher the speed, the tighter the margin of error. to move to the back, you have to be going slower than the rest of the bunch… to get up to speed and slot in at the back, you have to apply more power for a second. it’s a simple enough concept, i’d think