Relation of Power output to speed and racing time in Time Trials

Hello everybody,
I am relatively new to Zwift and especially to racing on Zwift, so please excuse if I’m asking something obvious. I did my first Time Trial just now (Koa Sports League Time Trial , 01/19/2021 at 9:30 a.m. UTC+1) and have a question regarding the results:
I came in second place in the B race (just six riders started) with 4.07 W/kg and an average power of 350W (I am quite heavy with 86 kg). The winner of the B race was almost 40 seconds faster with 4.07W/kg and 305W average power.
I used a Cervelo P5 with Zipps 808, according to Zwiftinsider one of the fastest TT setups until level 30 in Zwift. As drafting is disabled in time trials, I am wondering how the winner of the race was able to gain such a huge lead with the exact same W/kg but an even lower average power. He can only have used a similar setup, as he is only level 28 on Zwift, thus can’t obtain disc wheels etc. This winner of the B race was even 24 seconds faster than the second place in the A race, although that rider put out 4,33 W/kg and 316W average power.
I must be misunderstanding how power output translates to speed and time in Zwift, can someone explain to me how these differences in racing times can occur?
To clarify: its not so much about why I have lost the race - it is more about what else is there to consider and pay attention to the next time, so I will not loose 40 seconds although I am putting out the same W/kg and have an assumed similarly fast setup. I totally understand why in an ordinary race with drafting etc someone with lower statistics can win the race just with clever riding (riding in the pack and conserving energy etc.) But in a flat time trial I thought it would all come down to power output, which it obviously doesn’t.

Thanks a lot

P.S: Please excuse my grammar, I am not a native speaker

Averages don’t tell you the whole story. The other rider might have put in more power in key places and backed off more in others.

Hey Steve, thanks for your reply. I thought about that too, but in Tempus Fugit there are no real key areas, apart from the start, as it is pretty flat. Attacking at those few rather bumps than hills makes up for 40 seconds?

I’m not sure. But bear in mind that it’s not only about power - see How Does Zwift Determine My Speed?

It could be that the other rider had a more aero frame/wheelset, he was a bit smaller so more aero, etc.

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Were they using a Sterzo?

They may be shorter than you.

Going purely on average power only really works on hill climbs. On other events 2 riders might have the same average over the event but differ in when they applied that power, to different effects, during the event.

Unless the course was short and pan flat of course.

Looking at the numbers it look like the other rider weigh 74kg that is 12kg less. So he is probably shorter as well therefore less frontal area and that mean less drag. Also Weigh do play a role in rolling resistance so he would have had less rolling resistance.

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