It’s this time of the year that I am trying to do some structure and super keen to use the Forecast AI this time. But I run into what seems to be a problem.
My xert signature:
PP: 1069
HIE: 23.5
TP: 294
LT: 216
Xert’s power curve (estimated?) vs my actual 3 month power curve:
PP: 1069 vs 980
5’: 349 vs 301
10’: 313 vs 270
20’: 294 vs 264
I feed identical data to xert and to goldencheetah/strava etc that the actual numbers have been taken from. So there is no data issue. In addition all the files are inspected for errors spikes etc before been upload. I also have dual recording and shows that both my power metres are nearly identical.
I am riding with power the past 10 years and with multiple devices. In no way I could ride with 294 watts for 20 minutes. Well, used to in my 40s but that’s a long time ago! The best I can hope for 5 minutes when all stars align is 310-315, but I can’t do 349.
When I set my goal, I ignored the absolute numbers and asked for a 20 watt increase in 5’ (breakaway specialist) so that was not a problem. But:
But tomorrow the training says “Low Intensity Training”, “Pure Endurance” for 1:50 and 110 XSS. The prescribed work out (Sweet-Spot @90% - Classic 3x20) has 3x20 minute long intervals at 247 watts. That would be OK if I could hold 294 watts that xert thinks I could but the reality is that my best performance was 264 watts for 20 minutes and I thought I would die from it. And the day after tomorrow, I have to do a high intensity workout.
That can’t be right, can it?
For the record, I am doing a lot of maximal efforts in my activities from sprints while fresh (not at the end of a hard race only), 3-5 minutes attacks and steadier pace TTTs (all in zwift this time of the year). I am also using xert for years and it’s loaded with all my data.
I would say yes you have an issue, assuming those max efforts you refer to are really max and recent. You could plug the results of those (sprint, short effort, longer effort) into the power curve calculator and compare the results. You could then manually apply that calculated signature so it’s used going forward. It’s not so hard to do but support team can also help, as if there are historic data issues, you also need to decide when in your history to make the change…
As to why, we’d need to see some recent breakthroughs (when was the latest? Have you achieved multiple breakthroughs around this level which indicate you can achieve your current signature etc). Maybe also your progression chart showing the evolution of your threshold or focus power will show a sudden jump in from a certain breakthrough…
Thank you for your replies. Here are more details:
Actual 60 day power duration curve. My only comment is that my shortest effort is around 15 seconds. I can’t do those crazy 5 second sprint kicks I’ve seen people do without risking injury. I am pretty clumsy.
18 November (last breakthrough), TP from 266 to 278 and HIE from 21.1 to 24.0: Xert - Activity | Zwift - Race: Club Ladder 5430 (E) on Gotham Grind in New York This one is very puzzling. It was a moderate paced race with just one 20-30 second sprint in the end. It’s not even the highest, with 618w for 30s as opposed to a ride 11 days earlier that I had a 742 w for 30s.
I think, it was all going more or less as expected until the 18th of November. I could flag that but I have no idea why I should. The data is good quality and consistent with my performances.
In your OP you mention TP of 294w - where does that come from? The last BT says 278w?
If this is the source of most of your power curve above, then I would say that that power curve is not representing max efforts, so would not suggest using the signature from the calculator. After a max 5min effort you’ll be hardly able to turn the pedals let alone set a 20min max as part of the same effort. (I’d also note it’s not far from a BT)
This is because Xert is not just looking at max efforts vs your power curve. Rather it’s modeling power vs MPA at all points in time, which also takes into account fatigue… you had more fatigue (lower MPA before starting the effort) in the 618w effort
From what you’ve shared I suspect your peak power should probably be higher, and HIE higher too, with some reduction in TP. I would go to your recent BT and you can manually tweak parameters so that it’s still a BT (MPA = power at the max effort point) with a threshold power you think is realistic, then save… note though, that TP is not exactly FTP and you are unlikely to be able to hold TP for an hour
Oh, no! It looks like I pasted the estimated 20m power from xerts’s power duration curve. My anticipated TP is 275 w at the moment. Apologies for that.
After a max 5min effort you’ll be hardly able to turn the pedals let alone set a 20min max as part of the same effort.
Hmm, that makes sense and it’s silly I haven’t realised it. So, I should try and do an isolated 5 minute best effort which will then hopefully result in a better HIE, which seems to be off.
This is because Xert is not just looking at max efforts vs your power curve. Rather it’s modeling power vs MPA at all points in time, which also takes into account fatigue… you had more fatigue (lower MPA before starting the effort) in the 618w effort
Right. And maybe I had less fatigue if my true HIE is higher. I can see that.
From what you’ve shared I suspect your peak power should probably be higher, and HIE higher too, with some reduction in TP. I would go to your recent BT and you can manually tweak parameters so that it’s still a BT (MPA = power at the max effort point) with a threshold power you think is realistic, then save… note though, that TP is not exactly FTP and you are unlikely to be able to hold TP for an hour
I will do that, I am pretty familiar with changing and locking signatures. I suppose I still need to edit the signature on that activity and then try to do a better max and 5 minute efforts.
No problem
I think a 5 minute test (or other short duration - I personally choose 3 min) is a good idea. You may find that your signature isn’t so far out. The only reason I think HIE may be understated (and TP overstated) is because you say you couldn’t hold close to your 20 minute power for 20 minutes… you could also try a 20 minute test on another day
Am curious what you find out if you don’t mind sharing
That’s better. 3 minutes is more doable. 2 less minute contemplating why am I doing this I have a mental difficulty doing those maximal efforts indoors, hence I have based this on racing only, where I get motivated. When I used to ride outside (living a year+ with a damaged shoulder, so I now ride on the trainer), a 3-5 minute hill would do the trick. In fact all my 5 minute efforts were on a specific hill/strava segment. Yesterday I baled out after 90 seconds from my effort but I will aim to do something and update. Thanks!
I did my first 5 minute attempt last week: A hill climb race with a 5 minute hill was a good motivation. I had a 10% increase in 5 m power (from 299 to 329 watts). I probably had 5 watts more, as the 330 was my made up target and I definitely had more in the tank.
I was not very close to a breakthrough (activity) but not far either.
After extracting manually a signature on the activity that skyrocketed my TP (here) and getting recalculated a month’s worth of activities, my current signature is this:
The endurance workouts now feel right: quite a bit of work but comfortable with the green to be hard but sustainable (as I would expect them). They are also feeling empowering, in the lack of a better word.
I don’t have a big experience in workouts but it feels right at the moment, so I will go with it and planning a 20 minute effort sometime in the next week. I suspect that now that endurance days are endurance instead of workouts to failure, my TP is not far off.
I have a mental difficulty doing those maximal efforts indoors, hence I have based this on racing only, where I get motivated. When I used to ride outside (living a year+ with a damaged shoulder, so I now ride on the trainer), a 3-5 minute hill would do the trick. In fact all my 5 minute efforts were on a specific hill/strava segment. Yesterday I baled out after 90 seconds from my effort but I will aim to do something and update. Thanks!
