The systems does some data checking/validation to designed prevent errors in power data (specifically “sticky watts”) from skewing an athlete’s signature. repeated data points of the exact same power and cadence are very unlikely - even the smoothest pedaling cyclist will have variation in their second to second power output. In cases of repeated data points, it’s more likely the power source is incorrectly sending the same data point repeatedly.
If you’re near your limit (e.g. MPA is near your power) and your PM incorrectly reports an additional 4s of power data that aren’t valid (or if this were to happen many times during micro-intervals), it could dramatically skew your signature higher. So the systems tends to be a bit conservative in these cases where high power & cadence data points are repeated several seconds in a row.
I could see the benefit to having tools to crop or correct power spikes, etc. directly within Xert’s activity details page. Perhaps we can include any data points that have been flagged for errors & allow the user to revert the changes, if desired. That could be neat & allow override if we’re certain that the data is valid.
Yes I agree, the system should say hey some of your data has been flagged, are you sure it is correct?
Here are 2 screenshots showing only 4 seconds of the same exact watts. This sounds unlikely to have 4 in a row exactly same power, but on rollers and you’re at about what you can do and that’s it, I can see it happening especially if you’re unable to raise cadence higher. I know in the grand scheme of things these missing 6 seconds are absolutely nothing, but you don’t want users to say hey I see the data in WKO5, I ran it through dcrainmaker analyzer, I can see the exact numbers, and xert changed them? How many other rides have been massaged without me knowing? Having confidence that the data is the data as it is shown is important to people.
I get what you’re saying about bad data affecting the signature, in this case Xert mistakenly made a change and now I’m left wondering what else it has done (probably still not a big deal).
One other thing: Why would it choose an arbitrary wattage number? If it was concerned about 4 seconds in a row at 375w, how did it come up with a solution of 280w? The context around the 375 does not suggest 280w.
To clarify while I was riding on zwift, this file was directly off a garmin. I just have my powermeter also send data to zwift, but I never use the file that zwift generates. I’m not on a smart trainer.
The Zwift Insider article implies sticky watts can be common with a number of power meters.
What brand pedals do you have?
Since you don’t use a smart trainer what is the maximum watts you can reach on standard rollers without any resistance control?
I assume sprint workouts aren’t practical, but can you hit most micro-interval targets following Magic Buckets guidelines?
Could someone reach their 30 second power on rollers and hold it for a few seconds? Or would you spin out before you got there?
It’s a powertap, has been golden forever. Never a problem. These weren’t sticky watts, I’ve looked at a zillion power files from this powertap and it’s never an issue. 4s in a row of the same power in my opinion shouldn’t prompt a system to flag the file and make weird corrections, if in fact that’s what happened here.
Max watts on rollers without resistance is not even close to what you might get on the road or a trainer. Even on the smallest drum rollers, max power maybe half unless you can spin like a keirin racer.
100rpm in the 53x11 at 80psi 28mm tires is around 400watts. Included PSI because it makes a big difference on small drum rollers.
