TT finishing position to power output

General Discussion
#1

Hi, I done my first TT today and have a question if anyone could help. I rode the zwift fast Friday tempus fugit TT. This course is 17.6 km long and really flat. I averaged 293 watts (3.0w/kg) and the person that finished 1 second ahead of me averaged 189watts (3.3w/kg). Unless I’m missing something I can’t see how that happened as the power difference is substantial and the course is flat so w/kg shouldn’t be that important. If someone could point out what I’m missing it would be greatly appreciated.

Thanks

Dan

#2

Your Zwift profile is private, so I can’t see the activity details (or any photos associated), but here is a potential reason: Were you on a standard bike, with regular wheels, while the other person was on a TT bike with disc wheels? I’m not sure how much difference that would make over the distance of this TT, but might make some. There may also be differences in where they applied their power vs where you applied yours that could cause some differences. I believe that there is also some difference in ‘air resistance’ due to rider height that might come into play, depending on the relative differences between you and the other rider.

#3

Hi Nigel , thanks for your reply, I have changed my privacy setting so anyone can see activity now. I was n a TT bike but only the standard one you get I am quite a bit rider so maybe some more drag there. Just wasn’t expecting it to disadvantage me that much.

Thanks

Dan

#4

293 W and 3,0 W/kg you are about 98 kg, I assume perhaps 190 cm tall?
The other rider has 189 Watt and 3,3 W/kg, means he has 57,3 kg (?!?) and is much smaller.
Not sure if it would be the same IRL, perhaps look at this:

I am not lazy to look, but my phone has small display and my old eyes don’t like it :drooling_face:

#5

And perhaps it didn’t. I mean, clearly Zwift thinks there was that much difference, but I’m not well-versed enough in the Zwift dynamics to understand it all. My general perception, also, is that higher actual power makes more of a difference on flat terrain, while WKG becomes more important as things get steeper. And the power difference you listed (you putting out about 1.5x the watts of the other rider) would seem to me to be a pretty significant.

#6

Just looking at average power is a bit hard to judge the effort. Remember that route is not 100% flat there are a few bumps. The lighter rider did not have to push any harder to get over those bumps, but as a heavier rider you will have to push a lot harder. Looking at your power profile it does not look like you pushed harder on the bumps and the first bump you were lower than your average power.

On a flat road you have other factors that are also influenced by weight like rolling resistance (F=Cmg) (Rolling resistance = Constant * Mass * Gravity) so more mass = more rolling resistance.

I would also assume the other rider being a lot shorter (being a lady) therefore a smaller frontal area.

1 Like
#7

Thanks for all your replies everyone. Looks like it’s going to be down to a range of factors that is beyond me to try and work out. I’m not planning on shrinking myself down any time soon so better work on my power.

Thanks everyone

Dan