[Closed] Zwift Physics

Is the ftp a number that the user enters? Or do you have to do the test in zwift, which presumably you could soft pedal though

Zwiftpower members can manually enter and adjust the FTP in their profile, but your category is based on the average W/Kg of 95% of your best three 20min efforts (just races and TTs, not group rides?) in the last 90 days.

You can adjust your weight via your profile at Zwift.com and then click "refresh profile" to sync that stat to Zwiftpower, no limits, but changing your figures wildly and rapidly while racing and TTing will often get get reported on https://zwiftpower.com/viewtopic.php?f=11&t=5612 and possibly result in sanctions.

So taking my own modest profile figures https://zwiftpower.com/profile.php?z=588304

I set FTP to 280W after the Newbury TT on 6th May, after a best 20mins of 295W (using my 4iiii for power) https://zwiftpower.com/events.php?zid=704776 , which is now 5 weeks ago, so I need to try and do another effort in the next week to see where I am now. 3.59W/Kg 95% figure when I was ~77.8Kg that day.

But my best 3 efforts in the last 90s days are from when I was lighter (as low as ~76.3Kg) and a bit stronger (~294W in early March and been steadily declining until that Newbury TT effort), so Zwiftpower is working on 280W and 3.61W/kg 95% figures...

Even though I was ~79.5Kg when I weighed myself a few days ago, but that still puts me very safely in just below mid Cat B category at ~3.5W/Kg.

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In other news, been trying a few of the new "Zwift Racing" workout plan events recently, some have been quite fun... But don't think if you run a race sim workout at the venue of that sim, the intervals will sync with where you are on the track, I tried the New York Grand Central at the venue and it was mad doing my biggest efforts on the KOM descent! 😆

Crit City sim was quite fun, lots of very short intervals, not so great for getting ERG to power match (it does recvommend turning ERG off) but fun nonetheless.
https://whatsonzwift.com/workouts/zwift-racing/

integrating a load cell sensor with a wifi connection into one of these rocker plates that are all the rage nowadays probably wouldn’t be that hard…

The thing there would be your bike weight would matter, your wheel base would effect it and so on, you'd just fiddle the calibration if you were bothered enough.

You've got to assume everyone plays by roughly the same rules (like PEDs and so on) but that's a very different issue to the physics of the thing.

The issue in the OP isn't (solely) one of weight doping, as its "flat" it's really how does 200w beat 300w, and that's down to not understanding the way zwift works rather than specifically any cheating. There's no moaning in the OP about being able to take the bends on the alpe for instance at 70mph on the way down. The physics are the same for everyone.

The thing there would be your bike weight would matter, your wheel base would effect it and so on, you’d just fiddle the calibration if you were bothered enough.

I would assume anyone willing to go to those lengths would be obsessed with super-accuracy and definitely NOT cheating

You've not done much online gaming have you?

The physics do overly favour light riders on the flat.

Although it might be the other way about in that it over penalises heavier riders - you see it in the TT races on tempus fugit (flat, everyone on a tt bike, no drafting) there are riders on similar time with a huge spread in power. The last TT i did there was someone who did over 460w and he finished a few seconds ahead of someone who was under 300. Both took about 23 minutes...even if someone has a poor aero position in real life on their TT bike then 460w will be significantly quicker than 23 minutes for a 10 mile TT.

To be fair the 460w is probably a miscalibrated turbo anyway, but just using that as an example.

You’ve not done much online gaming have you?

Does IDKFA work in Zwift? What about IDDQD?

460w will be significantly quicker than 23 minutes for a 10 mile TT.

Quickly dumping the numbers in to bikecalculator.com (which tends to be about right for me in terms of on screen speed to power)

@5w/kg
That 460w rider weighs 92kg and will do 42.7kph on an absolutely pancake flat route so should cover 10.23 miles in 23 minutes.

The 300w rider at 60kg does 37.2kph on the same (zwift puts me at 36kph at 300W:80kg on the standard bike)

On that same 10.23 miles they'd be at 26.4 minutes so over 3minutes slower.

Zwift adjusts areo for weight and height.

According to ZI:
There's 30seconds difference between the zwift TT bike and the cervelo p5x on tempus fugit at 300W
53sec between the standard wheels and the zwift 858 super 9s.

So that's almost half the time difference under an identical rider and the speed increases aren't entirely cumulative, wheels & frame upgrade is better than simply wheels + frame upgrade.

Also https://zwiftinsider.com/how-height-affects-speed-in-zwift/

"a 5′ tall rider will be ~2 minutes faster than a 6′ tall rider for every hour of riding on a fairly flat course"

Weight on flat routes (2 laps tempus fugit) makes a big difference
https://zwiftinsider.com/rider-weight-speed/

82kg @ 300 watts: 52 minutes, 17 seconds (39.7kph)
75kg @ 300 watts: 51 minutes, 26 seconds (40.4kph) – 51 seconds faster

(that's 3.6 seconds a kilo on a single lap)

So...

On the same 10.23mi,with the best bike and wheels vs standard setup the 300W rider, assuming 1' height difference would be 75 seconds slower, not allowing for cumulative effects of kit, any gradients, or any difference in rider weight.

If the weight relationship we're linear (I doubt it is) the 60kg vs 92kg rider would be 115sec faster for weight, so 40 seconds quicker over all with best kit.