Varying results from same workout between two different people

My wife and I both did the same workout this week, Monitor. We are both on Wahoo Kickrs and both have been recently calibrated. When we looked at the analysis of our rides, there was a significant difference in the amount of time that each of us spent in “sweet spot” vs “Endurance” and we have been racking our brains as to how this is possible. We have different FTPs but I wouldn’t think that would make any difference. The workouts should give us the same breakdown of power zones, No?

Can you post links to the two rides?

Not sure how to post the links but here is the breakdown from my Strava feed.

|Z1|Active Recovery|1 - 58 W|20:58|34%||
|Z2|Endurance|59 - 79 W|2:06|3%||
|Z3|Tempo|80 - 95 W|23:41|39%||
|Z4|Threshold|96 - 111 W|14:16|23%||

|Z1|Active Recovery|1 - 96 W|20:06|33%||
|Z2|Endurance|97 - 132 W|2:13|4%||
|Z3|Tempo|133 - 158 W|16:08|27%||
|Z4|Threshold|159 - 184 W|21:34|36%||

We are both in ERG mode btw.

And those are definitely power zones not HR zones? Strange…

So I found your ride -

I don’t know your wife’s trainer road username so I cannot find that one

First thing I notice about your ride is that you aren’t dropping down low enough in the recovery valleys - probably because of the gearing you’re using. Try to stick to the middle gears on the cassette, even when in erg mode, so that the trainer can do a low enough resistance

As for the zone stuff - it looks like it is really just a rounding thing with how the zones are calculated based on your FTP.

Your sweet spot goes up to 167 and this ride has you right below that (mid 160s) for a long period of time. I think that’s likely what it comes down to - how the zones begin and end based on FTP % based on the %s this workout touches.

Hard to say for certain without her ride to compare to though

Endurance vs SS? There’s only 1 endurance block in that workout, right at the start. Not sure how you could rack up more than a few seconds there per interval transition. Do you mean SS vs tempo (monitor is -right- on the line)? In any event, the exact breakdowns are never going to perfectly match the workout design. Each rider and trainer has individual variation, even in ERG mode. As your cadence slows, the resistance get’s kicked up, eventually you catch it and up your cadence, then the resistance falls a tad. Kickrs seem to smooth the data out more, but the effect is still there.

Are you sure you’re not looking at my Cadence. The power does seem to show appropriate levels from the chart as far as I can see and I am gearing just as you say I should be.

My mistake - that is your cadence I was looking at

Are both FTPs set correctly in Strava?

A lower overall FTP will produce narrower zone bands and contribute to the difference in this way possibly?

For example a 200w FTP may have a 20% 40w Sweetspot zone where as a 100w FTP would have a 20% 20w Sweetspot zone.

You would think though that this is negated by the workout profile but could be worth considering.