Inaccurate Race Results - due to incorrect PC time

(Brandon Amos) #1


Today I completed a Zwift race.  I finished in the second group in the top 8 people.  After the race finished a leader board was displayed to screen via the Zwift PC software and I was not shown in the list of top riders (this 15 were shown)

I have completed some analysis and I believe Zwift look at the recorded end time of the race which is based on the riders PC time and this value is then used to compute your leader board position.  I also think zwiftpower also make this same mistake.  

I say mistake in the previous paragraph as a clock on a PC can either be slow or fast.  If it is slow then you will be penalized (I confess I since reviewed my PC clock and it was running 21 seconds slow which explains why your leader board did not include me), if however your PC clock is fast (like the two race leaders PCs appear to be you will can a higher race finishing position.

The Zwift system knows when the race starts.  I think at the point of starting the race the Zwift software should look at the PC time and compute an offset.  This offset should then be both taken into account when computing the final leaderboard Zwift show.  

To fix issues with Strava flyby and race results reported by sites like zwiftpower it would also be good if this offset was taken into account when writing the trackpoint times to the FIT file, ie my first trackpoint recorded a time of 08:00:21, subtracting a 21 second offset from all trackpoints would result in 08:00:00 being written to the file.


Without doing this you might as well stop showing the end of race leader board to screen as it is worthless

Thank you,


(Philip Amos) #2

I agree.  If you can’t guarantee that every bodies start times are exactly the same there is no point in having a results page as its meaningless.

You can’t rely on people making sure their own computers are correct because this is open to abuse and can result in people being given a higher position than they actually achieved because they set their time fast and gained an unfair advantage.

(alex shank) #3

it uses lag corrected synced server time. nothing to do with your local pc time. 

(Brandon Amos) #4

If what you say is true, and I’d be surprised if it wasn’t as it seems logical then I think the issue might be related to the fact that races now include warm up laps and I suspect the leaderboard includes the warm up lap and not the final race lap.

since posting this I’ve reviewed Strava and segments used for the races in Zwift power are now incorrect as they include the warm up and not the final race lap.

(alex shank) #5

also the kiss race you are talking about had only 1 group. not two groups.

(Eric C. (Zwift HQ)) #6

Basically what Alex is trying to say is that your PC clock has nothing to do with race results in Zwift and the race itself had one group, so even if you are labelled “B,” there is only one group and only one set of results, which would include everyone from “A.”

We don’t run ZwiftPower so I have no comment on how they decided to list their winners.

(Philip Amos) #7

It would be handy if Zwift had the ability to see the leader boards after the races are completed.  There is no reason that the Zwift Power site should exist but it does because Zwift doesn’t have the feature.

If Zwift had historical leader boards they would be far more accurate as they would know about warm ups and the rules of the race etc and where the actual start and finish lines are and who crossed in whcih order.