Rider to rider power on a group ride.

Hi all relatively new on Zwift so please forgive me if this is obvious. Last night i rode with a bunch where the declared power was 2-2.5w/kg however after a lap at 3.5 -5 w/kg i pulled the pin and went for a sulk. The thing is that i rode in the middle of the bunch and surrounding riders were without exception making considerably less power, around 2-3w/kg. I’m 66kgs. What gives?

If you were on a flat road then It would make sense that heavy riders will go faster at fewer w/kg. on a flat road I do 38km/h @ 260w and that is 2.3W/kg and for a smaller rider to ride at the same speed they need to generate almost the same amount of power and that put them at higher w/kg. 

But: in the mountains you will fly past the bigger guys.

Heavier riders will push out less watts per kilo at the same wattage as you. Their total wattage per kilo has to be divided by say 90kg whereas your total wattage per kilo only has to be divided by 66kg.

A 66kg rider pushing out 220 watts will be riding at  3.17w/kg

A 90kg rider pushing out 220 watts will be riding at 2.32w/kg