Group workout and algorithm to calculate speed

I did my first group workout today. It was fun and there were absolutely no glitches.

My only concern to point out is I was generating 340 watts on flats but my avatar was only going 18 MPH. I realize that the whole point of a group workout is to keep all of the avatars together, regardless if one person is generating 340 watts and the other is generating 120 watts.

The main problem with this is now I have 12 mile ride logged, which based on my power output and elevation, it should really be more like 18 miles logged.

I understand that this is not a big deal, especially since group workouts are not a common aspect of my overall training plans.

I can’t really offer any solution either. At the end of the day, it was a hell of a workout for me even though it looks like I took a rest day on paper.

Did anyone have any thoughts to add or ideas? Thanks.

Hi Tyler,

Welcome to Zwift and I’m glad to see you’re enjoying the workouts.

Game physics apply to Zwift so while higher wattage generally does mean faster speeds, there are other variables including inclines, draft effects, road surfaces and which bike/wheels you’re using. They all affect your speed in the game.

Steven , did you Not read his post, clear he was in the Noob train, that Cap your SPEED.

Tyler: Seem you you get the idea of how it work. I don’t think there is a solution but I also don’t think there is a problem. 


You should judge your training based on TSS (Training stress Score) not distance covered. Many people can ride 300km per week but not a lot of them can do 400TSS in a week.

Or you can track your power numbers.

I’ve stopped doing group workouts on Zwift for this very reason. The pace is slow, really slow and riding up hill is like wheel spinning in mud. I did a recovery ride on Richmond yesterday and was passing what was obviously a group workout despite me putting out less watts than many of the people doing the workout. Almost as though speed is governed by the slowest rider in the group.

Nigel: I would assume the speed is based around the slowest rider, no one want to set a unrealistic PR during a workout that they wont be able to better ever.



Hi Gerrie. I get that. However if it’s an issue they could always delete the ride on Strava. This is a bit like if I do a RL race and get PR’s as I often do. I’m getting the benefit of the draft. The only way to beat the PR is the following year doing the same race.

Are you feeling cheated from not having enough miles to show for the workout with respect to leveling up or unhappy at how slowly the virtual world rolled by?

I lead group workouts. This is not an official answer. But, here is what I know. In order to increase the draft, an element as a headwind is applied. This helps keep the group together and does slow speed as compared to any other type of riding on Zwift. This is why most group workouts are on flatter courses. There initially was a problem with hills in group workout, but I had one on Fox Hill not long ago and everything went smoothly.

One of the important aspects of this function is to prevent group workouts from becoming a “super-blob”. This would either ‘capture’ other riders on course, sucking them helplessly along unable to pass. Or, riders not in the group would have a super speed as they would be able to draft and pass at supersonic speed, creating an unfair advantage.

Thanks for the discussion everyone.

I don’t really have any major complaints or solutions, it just is what it is. I wanted to open the topic up for discussion so I could make sure I wasn’t missing anything obvious but it sounds like everyone is on the same page.

I guess at the end of the day the workout speed needs scaled for all riders. Some high power riders will have ridiculously low speeds, and some low power riders will have very fast speeds.

Ideally Zwift would calculate all power outputs of riders in a group workout in real time and try to set a speed that is most in the middle for everyone, and maybe they already do.

J. H. Edmund Lee -  mostly it was psychological during the ride. I was in a real spot of bother pushing a lot of watts and getting a hell of a workout, but my avatar was going so slow that it was mentally depressing.

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