But wait how can anyone debate the fact that riding at altitude gives you less power than riding at sea level?
Sure, you make less power at altitude. The amount less varies quite a bit depending on your physiology and how long you have been at altitude.
Zwift should not attempt to give a correction to account for that though
Right. Because we wouldnât want to have a fair, level playing field for races in Zwift.
This seems like a reasonable option for race organizers (not outside of racing).
Oxygen affects aerobic power but not anaerobic, from what Iâve read, which is sort of obvious. So as power increases, the the component from anaerobic mechanisms increases, the power boost should be less. This can be estimated from FTP.
In the Ineos LâAlpe race, Egan Bernal was the obvious choice to win, but since he was riding in Colombia, at altitude, he was at a disadvantage, and Rohan Dennis won the race. This would have been an example of where an altitude adjustment would have made sense.
But for âimportantâ races, where maybe more verification would be wanted, the feature could be turned off.
And if weâre going to go down this rabbit hole, shouldnât Zwift also put an impairment on riders as they ascend the in-game climbs? That is, as you ride up the Alpe your performance should go down.
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Altitude does impact the human boyâs ability to generate work, since the lower ambient pressure limits the amount of O2 that can enter the bloodstream. Acclimatization does reduce the impact, but does not eliminate it. So thatâs that.
Now - as to whether Zwift should compensate for that, I believe thatâs slightly entering science fiction. Racers in a virtual event are in different conditions to start with - different ambient pressure, temperature, time of day, all of which have an impact as well. And thatâs not mentioning trainer/power meter type and calibration. You cannot reasonably expect all variables to be accounted for.
Build a hyperbaric chamber for you Zwift events?
Good points, Robert. I realize there are other factors that could contribute to a riderâs decreased power output, but none of the ones you listed, or that others have mentioned, seem to have the potential to affect a riderâs output as much as high altitude does.
And the thought of creating a hyperbaric chamber to train and race in has crossed my mind several times. That would probably be quite expensive though. But if I could breathe in oxygen as dense as sea level riders, that would definitely level the playing field a lot in my mind.
Ultimately, this isnât a huge problem. Itâs an interesting discussion to have and it would be great for those of us high altitude riders who like to race on zwift to have the option to have our power adjusted based on our altitude.
But itâs not the end of the world if we donât get that. It just means that those of us at altitude canât take zwift racing too seriously, because the game is currently designed to favor sea level racers.
cheers 
You should never take a video game too seriously unless it is your livelihood. In which case you would not be living at altitude due to the disadvantage it puts you in.
On a side note hopefully clubs will allow the organization of races with club members. This way club organizers can make their own adjustments either via weight adjustments or restrictions of who can enter their club races.
yup. Great perspective, Vice. I think sometimes I can get too wrapped up in competing, and with races outside cancelled from the pandemic lockdown in our area, Iâm a bit hungry for competition, and Zwift and RGT are the only places I can do that for now
And thatâs a great idea about allowing meetup/race organizers to level the playing field within their own organized races.
Weâve started doing that with our team a bit, where we have a âsea level divisionâ and an âaltitude division.â
This counts more for IRL riding but this is also a interesting discussion. training - Power Output at different Air Densities - Bicycles Stack Exchange
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Thanks for posting this, Jonathan. This sentence from Joeâs article sums up the reason I started this thread in the first place:
âThe bottom lineâŚwas that as the altitude increases aerobic function decreases and so FTP decreases. And as you acclimate to a new, higher altitude your aerobic function and FTP improve, but they never attain the level you would have at a lower altitude.â
There seems to be at least 3 solid studies that have been done that would provide conclusive evidence that acclimatized riders at higher altitudes have a power loss as a result of lower oxygen density.
I still wish the Zwift team would account for this 
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Iâve live at 9600â in Summit County for 15 years, and would love to see Zwift provide altitude correction. Last year I was in cardiac rehab in Vail, and they oxygenate their workout room. Felt good! I donât know how much it costs, but think it would benefit my high altitude training, i.e. sleep high - train low? For anyone interested, I came across this company:
altitudect dot com/oxygenating-mountain-homes/
Great info and discussion. Iâm just joining Zwift from north of Taos, NM at 7,600â, about the altitude of Mexico City, and wanted to see if there is an altitude correction. Totally get that you canât correct/confirm for everything. Iâm guessing that in the future, all athletes will have a participation passport that will take most variables into account. I have a natural hematocrit level of over 50, which would have disqualified me from the TDF (as ifâŚ) and although I love living at altitude, I sleep like a log when I drop down to sea level. The âsleep highâ, âtrain lowâ concept has been viewed as gospel, but it doesnât take into account the massively restful sleep - and recovery - you get at a lower altitude. Would like to see any updates to the data. Cheers!
Iâm so for this! Please can Zwift use the GPS altitude data in Zwift Companion to make things fair? My car let alone me is 10-13% down on power compared to when we are at sea level!!!
Whenever I race at sea level it feels so good, just that much easier with and extra 30-40w on tap. I had a PB on a climb on the coast that stood for two years - I wasnât even trying to get one, just trying to shake off some wheel suckinâ locals he he.
(Iâm living and racing at 1600m/5249ft)
To get an idea of the effect just look at when Rigo races on Zwift when he is at home in Columbia and you can see how much harder he has to work.
This is accurate. Once you are acclimatized you donât even get a training advantage. This is why hypoxic chambers exist⌠so you can trick your body into thinking it is at altitude during your sleep cycle. Canât imagine it is a good sleep though⌠I remember sleeping at 12000 feet for a couple of weeks⌠it was terrible.
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Not sure I get a GPS signal in my basement when I Zwift.
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Lovely place!! Off topic but you should hold some training camps up there. 3-4 weeks first week is super easy to acclimate, then itâs full gs until you go home.
Cell phones can triangulate position from cell towers and so altitude as well? As long as your phone gets a signal altitude should be able to be worked out.
The majority of people donât Zwift on a cell phone though. Yes companion is there but it all sounds a bit much to me to try compensate for altitude when itâs going to be so easy to cheat the system.
You canât force people to use a cell phone and if you are relying on computer IP/user address that is easy to spoof.