It’s very important when considering which metric to use that there’s an understanding of steady-state versus a mix of efforts. A 30 kph “average” is not necessarily a flat 30 kph for the entire event. There’s also group draft to contend with - it’s not unusual at all for me, at 83 kg, to be moving at 40 kph while only tapping out 0.8 w/kg due to a large group “blob” in action.
Perhaps many are confusing w/kg in a mixed group context with the concept of % of FTP which is commonly used as a workout metric: with % of FTP being equal between two riders of different abilities, both riders are experiencing the same degree of effort relative to their individual abilities (an hour at 90% FTP will feel just as hard for an elite rider’s fitness level as the same hour at 90% FTP would for a rider of lesser fitness) - but, if they were riding together, they would certainly not remain grouped for long. This accounts for the “rubber band” feature in group workouts - if there were no banding, group workouts would splinter quickly.
Every event will have a different feel based on route choice, event type, and riders in attendance - understanding how each of these metrics works in context (speed, w/kg, %FTP, group draft variables) helps all riders achieve personal success during their rides. @Patrick_Ascenders_As makes a great point about that balance of concepts, and I try to use similar communications to riders during WSR events.
Great back-and-forth, folks - love this kind of discussion.