New and have questions about threshold power curve

Trainer Road user and MTB rider…just subscribed and brought in all my data from Strava. Struggled with import after going from free to paid.

I seem to have activities which are doubled, must have been because I connected to Garmin, and switched to strava. Deleted all of those dupes.

I have a very large breakthrough showing on Nov 25th. When I flag it, it continues to show in progression chart. Does its data look spurious and why does it not go away when I flag? When I have that large bump, does it impact the threshold data in the weeks after? The threshold stayed relatively high after that bump…is that because the rides after are legit?

I use a Garmin Rally pedal power meter outdoors and wahoo kickr gen 5 inside.

I would like to see a 2 year progression chart to contrast the last 12 months where I made some big diet changes. I cannot select a custom range, it does nothing. What am I missing?

The huge jump finally stopped showing, but the question stands when I put it back in. Is it right to keep it or flag it?

If I remove it, there is another big step up on the 26th December. Could it also be bad data? Concerned my power meter is whacky.

For further input, my AI FTP on TrainerRoad is sitting at 260.

Flagging an activity retains the strain score but removes signature calculation.
Xert normally ignores power spikes during analysis. However, you can enable Max Power on the Activity Table, sort by that column, and flag any suspect entries there.
If you still question the results, post a screen shot of your XPMC chart set to 3 Months or Year.

To select a custom date range for the XPMC progression chart, set filter to Forever, then place mouse pointer on start date you want (date shown at bottom) and drag highlight to end date or Today line.

When viewing the progression chart after activity edits it’s a good idea to refresh browser page to clear the cache.

Welcome aboard. :slight_smile:
Lots of newbie tips in my Onboarding post –
Onboarding steps for Xert Trial users and newbies - General - Xert Community Forum (

Thanks, its the big steps I am questioning.

That large silver BT jump does look unusual considering your TL history and prior BTs.
Drill down on that circle to view activity details, select the BT report icon, then download and post that report here.


I’d be wary of the data from these activities… Seems the data from those activities may be invalid.

+56 W to Threshold isn’t necessarily a problem unless there isn’t anything else in the data to back it up, like a large jump in training load.

What you might consider is to remove the power data (using field stripper tool) and re-upload to Xert. You can allow Xert’s HRDM to re-analyze the activity using the HR data instead.

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would deleting the entire ride make more sense?

That would also work, yes!

Question, why, after a big step up in TP, if it is suspect, does it stay elevated across many rides? For example, after the big one in Nov, I have 21 rides that are now at that similar new stepped level. Would this not eventually drop if the original breakthrough was based on spiked data? For instance, last night’s ride was on Wahoo trainer, which is different power data source than the breakthrough outdoor ride and it has a TP not far off the big spiked one.

Unfortunately the system can’t always discern what is valid data or not. It just analyzes what is uploaded. We make some efforts to prevent data spikes from skewing signatures, but it’s not always perfect. Looking at the historic relationship between Training Load & Threshold makes it a bit easy to see potential outliers, like at the tail end of this XPMC you shared:

The system generally uses the signature from the preceding activity (plus any time since that activity along with decay method) to determine the starting signature for a new activity. After removing the activities with invalid data, your Threshold should revert to the level it was before the invalid data.

it appears I need to remove or flag just about any outdoor mtb ride that I really go hard. I remove a suspect one, then a different ride pops and looks like a big step. Is that not the nature of a “breakthrough”? I can’t be that unusual in this regard…indoor are controlled workouts on trainerroad, outdoor is more random and depends on the day and the trails etc and how hard I am pushing.

Based on this data I went to Garmin on Monday on the potential that I have bad power meter… I just got a replacement on my pedals from Garmin so I will continue to sync and look but I am losing faith that this method of analysis is compatible with the spikey nature of trail mountain biking. Maybe it is better suited to road riding and the smoother nature of it?

Steps within a reasonable range are to be expected depending on number of days between BTs.
Big jumps without corresponding TL increases are suspect.

All outdoor rides are spikey. :wink: MTB more so.
Would you rate those BT event rides as tough based on RPE?
Here’s one of my BT road rides that was classified Tough Mixed Pursuiter Ride –

It was a tough ride back when I had high TL mid-summer and deliberately attacked every climb.

Compare that with an Easy Polar Endurance Ride –

I also have a few “bad” rides on file with suspect left crank power (overstated).
Profile looks similar but the spikes are out of hand and charts show too much red overall. As a result, the rides were rated Difficult when I know they weren’t. For those I used FitFileTools to scale back the power to get a more reasonable profile.

How does one know what to flag?
The massive one in november that looks like this:

Looks like this, which seems like what one would expect in the data?

This is another hard one where my pace was backed by the fact that I did a number of PR’s or top 3’s for me on trails I ride constantly…

One coming off a broken rib…so loafing

This is one that is just strange and I would expect to probably delete…but its not problematic in the overall state of the progression like the one at the top.

I have been riding trainerroad for multiple years and have used AI FTP over the past year and my FTP is 260, which feels about right based on training load. Garmin has me independently at 264 all based on the same data.

and here:

First, when talking about PM “spikes”, let’s make sure what is meant when. A short hard effort on a ramp during an MTB ride? If that leads to a BT thats totally fine and expected.

If XERT support talks about “PM spikes”, they rather might refer to exceptionally short power spikes produced by a temporary malfunction of the PM. Some PM models (e.g. pedals) are more prone to these than others. They are usually not supported by other data like alterations in elevation or cadence. If these lead to a BT, indeed, either flag the activity or remove the spikes via tooling.

Now, in general when training with different power sources, trainer and MTB in your case, I’d always recommend to compare them. Put your MTB in the trainer, make sure your record both PMs (trainer & MTB) with different devices and ride a little ramp like effort over a wide range of power. Then compare both resulting .fit files with
A bit of differences comes from the point of measurement (pedals in front and trainer behind power train) and is therefore normal. If you see significant differences, consider changing the PM you trust less. Alternatively, use the MTB PM also to record trainer rides.

In general, looking at the data you shared, I see you are at 3 starts (~75 xss) training load. On the other hand you do regular rides with up to 250 xss. To me that looks a lot like you have a underestimated signature/TP (-> BTs are much expected). Everyone is different, but personally, at 3 stars doing 200xss, I’d be wrecked for a couple of days and for sure would not repeat that soon after.

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Thanks very much for this thoughtful input and taking the time to look at my data. Yes, I guess the terminology is important!. I was thinking that suspect data might be a ride where the PM is reading extra high all the time vs very short and probably easily filtered out power spikes.

I probably should put the power pedals on the trainer but I feel like it has been done with these common brands as i have seen the tests and reviews and they are always single digit percentage points different, which for my amateur requirements are just fine.

Maybe I should accept that the data is as it is, and see if things converge across analytics to be in a similar zone. No two software driven methods are going to generate identical outputs when the data is so varied.

Question, where does Xert get my weight? I noticed at the top of each ride a “weight” reference. Most of my data, which all came from strava, has never had my weight at 154lb, which almost every ride shows until January 1st when the correct value from Strava shows up (185). Does xert use wieght in anything other than showing your watts/kg? It would appear anything prior to jan 1 2024 is the wrong lower weight.

You can edit weight for single or multiple activities by selecting Activities, Table from the menu, tick the entry or entries you want to update, then select the Weight button.

Sure, but one of your PMs might still have an individual issue. So I would still go for the comparison, especially if I’d have doubts about if my BTs are justified or not.

Alternatively, as a more pragmatic approach, accept your BTs (i.e., dont flag them), so you signature is updated and then try a workout with 3…4 diamons difficulty on the trainer while you are fresh. If you struggle to sustain it, work out whats going on with support.

When I was using Garmin Vectors , I found that breakthroughs generated by lots of on/off efforts, such as 30/15s intervals would also give me an inflated TP signature, so much so I’d have to flag them. MTB riding can be very on/off so it could well be that the data from those activities might be producing some strange results.

I’d also recommend , if possible, using the same power meter indoors and outdoors, especially with pedals as they’re so easy to swap between bikes. As the saying goes, “A man with two watches never knows the time.”

Like your saying here, but I try to have the data but keep things as simple as possible and switching pedals is not going to happen. I need to be able to suit up and go inside or out.
Interesting on your findings though with “on/off” efforts…which MTB trail riding certainly is.