Wrong poweroutput

Just joined the Rocacorba social ride Dec 21 @ 7pm
It was with dedicated bike.
I had output watts up to 4 w per kg to keep up with group.
Ending with 171m altitude @ 28km in one hour @ 207W avg. First time that poweroutput does not match speed. Other bikers had same altitude & distance but lower w per kg avg…is this Zwift issue or trainerissue ?

Hi @Werner_Van_Gorp

Welcome to the Forum.

That look like a flat route, on flat routes you should not look at w/kg but at only power (watt).

An oddity though… the 53kg leader only averaged 100 watts

Ok that is strange.

I would not think it is a trainer issue, Zwift calculate speed form power, so it will go as fast as the power you produce.

Did you use a MTB before the ride?

It was a dedicated bike ride…before I used a Tarmac S Works. The bike I always use…yesterday I did a 200w ride with 350m altitude @ 40kph…you see the difference…my weight is 68kg. To keep up with group I had to do numerous outputs of +250watts

Also…for a while my altitude seems to be stuck @ 87m…while I was climbing…does that ring a bell ?