Regarding zwift and group rides. If the power for a group ride is said to be between 2.0 and 2.2 watts per kilo. Can you really say that and keep the group together? As I understand it two riders of different weight will not have the same speed if both put out 2.2 watts per kilo or is that accounted for in some algorithm?
Always a conundrum and unknown since pure watts isn’t part of the listing. A 2wkg ride for a 60kg leader is 120 watts. However if the ride leader is 90kg, 2.2wkg would mean ~200 watts or 3.3wkg needed for a 60kg rider.
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Some group leaders will announce their weight at the start of a ride to give a better idea of pacing.
Neither raw watts or w/kg is a perfect measure, but I think that w/kg is better than raw watts.
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It doesn’t have be an either/or, but could be that both should be supplied. Though I guess that might offend some since then it’s possible to calculate the leader’s weight.
Not against the idea, but for rides where multiple leaders/sweeps are listed it becomes a bit of an administrative nightmare from an event creation point of view.
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Would’nt it be better to say that “We will have a pace of 30 km/h average” that is what you would say in real life so to speak.
I’ve said this before but Zwift knows how fast you should be able to ride. They wrote the formula which takes into account your height and weight to work out your drag coefficient and they know exactly how fast you could ride at any particular wattage.
Imagine if Zwift used the w/kg of an average rider in the event descriptions. Zwift could calculate how fast that average rider would travel for any particular w/kg and Zwift could also calculate how much power you would need to travel at the same speed as that average rider.
So, in addition to the w/kg range (for an average rider), imagine if the Companion app or the Zwift events page listed exactly how many watts you’d need to ride. Something like “You will need to average 217w to ride with this group”. Everybody’s watts would be different but it can be calculated (again, Zwift wrote the formula so they can work out how fast the average rider would go and how much power you’d need to match them) and displayed. And if you really wanted to be clever it would take into account the elevation of the course. Lighter riders would need more watts on a flat course than they would on a hilly course.
If events had multiple leaders/sweeps listed, then they could just look up how many watts they need to produce to ensure that the group rode at the same pace week after week regardless of who the leader is that week.
It would take the guesswork out of signing up for events when you know exactly how many watts are needed. This is the magic of computers, this is the kind of stuff that computers do brilliantly. I’m not saying it’s easy but it’s certainly doable by a competent programmer.
Fun to speculate but it’ll never happen though. Zwift is Zwift after all.
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As a new Zwift user I went on a group ride which is in my category (D) but was supposed to be 1.6-2.2 watts per kilo as this was to be an endurance Zone 2 ride. My 2.2 watts ( the top end of the stated power for the ride) per kilo would be 134 watts. I am only 61kgs but this would easily be within my Zone two. I got dropped after a hour as I was pushing into Zone 3 and needing to ride well above 2.5 watts per kg most of the time just to try to keep up. In the end I dropped off the power and came in 2nd from last but still with a higher average watts per kilo than everyone else ahead of me. Surely watts per kg is not an accurate way to determine the actual power you need to keep up in a ride? If the ride leader is 90 kgs riding at the listed 2 watts per kg (180 watts) and I am 60kgs I would need to ride at 3 watts per kg!!
It’s never about equal raw watts - w/kg is much closer for a variety of reasons.
But as a rule of thumb something like 0.1w/kg per 15kg of bodyweight gets people going at about the same speed. Drafting makes a big difference too, if you’re dropping out of the draft you have to work even harder to keep up, not helpful when your already having to work closer to your limit. And most ride leaders are experienced zwifters who are good at staying in the draft.
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Thanks for your response Tom, appreciated
Paul
Looks like the leader led at the top end of the listed range, averaging 2.2 w/kg.
But he was only 70kg, which is pretty average. The lighter end of the field had to overall average about 2.4 w/kg, while the heavier end was at about 2.1 w/kg.
Curiously, the lighter end riders showed higher 20min power, up around 2.8, while the same heavier end was at 2.3.
So, whenever it was during the ride that the 20m power was derived, you may well have had to be up around 2.9 or so for your weight.
Awesome, thanks for the info! and nicely explained. I can ride at 3 watts per kg even at 71 years old but thought it was too hard for a zone 2 ride, especially as I was looking for a bit more of an easier session. About a max of 170 watts for a hour will just about keep me at the very top of my zone 2 but still hard.
many thanks
Paul
Neither raw watts or w/kg is a perfect measure, but I think that w/kg is better than raw watts.
At the lower end of the scale (closer to 60 kg), I beg to differ. Every time I join a group ride, I need to look carefully at the terrain, and if it’s flat, mentally add something like 0.5 - 1 W/kg to the stated target, and then decide if it’s worth my time to join or not (usually it isn’t, which is why I’ve given up on most group rides unless they’re rubber-banded or if I really know the group well). Unless we’re going for a ride up the Alpe, raw Watts matter to me a lot more than W/kg (in which case I’m laughing as I drop the group for a change 
).
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Imagine Zwift actually using this data to get your ZRS Seed Correct instead of this disaster we have with CP30
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Your goal of the Zone 2 Group ride is a unicorn.
Should be possible, should be easy but is not.
I’ve spent all Summer trying to host a community Zone 2 Group ride and I can report that Real Life is just like Zwift.
For a Zone 2 ride, you will either have to ride solo or join a group with a significant lower W/kg than you expect to ride.
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Thanks Tim… Generally I do ride alone on Zwift TBH. Thought I would join a group ride for a change. Interestingly the day after I did that ride I did a pacer ride @ 1.8 watts per kg and found it miles too slow even for a recovery/ low Zone 2 effort. Had to keep backing off for the bot to catch up, gave up in the end and just plodded along to the end
Thanks again
Paul