Intervals.icu now has gradient adjusted pace for running using the same model Strava uses. You can configure running to use GAP for training load. There are also pace zones but no “time in pace zones” yet. You can control the default training load priority per sport.
Question: Should “time in pace” zones use GAP or normal pace?
Reasoning: For users with power data that mostly takes care of profile/gradient. For users without it might be more useful to use GAP. The problem I see with GAP is the quality of elevation data (imho both sources altimetric and taken from map data are not totally reliable).
If you have power data then that will be used for time in zones. I will need to make use of GAP data for load and time in zones configurable or perhaps auto-selected depending on the data. Strava do a good job of cleaning up the gradient data. I need to try do the same.
I can imagine this is tricky, also depending on the data source. Altimetry needs to deal with hysteresis, so there is probably some integration being done, and thus a time delay as it’s written to the fit file. Probably not all companies use the same algorithm.
If the source is map data, quality depends on region, GPS position…
So I can imagine different data sources need different treatment.
It also looks to me that Strava does a good job of cleaning up that data. So what ever they are doing, it seems to work.
Different companies use different algorithms. One of the biggest influences on altitude charts (from barometric pressure sensors) between different brands is the minimum delta used to count as an altitude change. Some use 3m, others use 5m or even more. I think they choose a value that matches best their typical pressure sensor. Most units do agree quite well if you do longer climbs. Differences are much bigger on rolling terrain. 30% difference in altitude gain is not uncommon. If your sensor fluctuates right above the minimum delta accepted, the unit is counting loads of faulty altitude gain.
Environmental barometric pressure change can be adjusted for when doing a round-trip because you know that start and end altitude are the same. So you can correct with a linear offset and be pretty close to reality. If not a round-trip you could take known altitude from start and end points from a map and use those to calibrate your pressure sensor.
There was a SportTracks plugin once that did these corrections quite well.
As soon as I can. I have a bit of a bug backlog to clear then will be on it (need to sort out issues with GAP on flat runs etc.). So I the next week or so likely.
Could you implement GAP for cross country skiing as well? You can use the same formula as for running imo. It will work well for uphill skiing. For downhill it might not work as well, but uphills are what people care about.
Your device is known to have correct barometric height. Then you can leave it on the default, Auto. @david is building a list of devices with correct barometric height in intervals based on info found on manufacturers website and/or user input
If your device is not on that list, you can set it manually. If you are sure that it has correct height, set it to YES and send the info to david. Once added to the list, you can set it to Auto again.
If your device is on the list but has a problem with the sensor or you prefer, for some reason, to use height from elevation maps, set it to NO
You can enable this. If you add pace zones to any sport you can choose to turn on GAP. If you do please let me know how it works. I don’t know anything about skiing.
I use the “Auto” setting and GAP on. But unlike Strava, where the normalized pace is always faster than the one without the GAP (I almost always run with a minimum of elevation gain); Intervals, on the other hand, shows me the pace with slower GAP. Am I wrong in the settings? My device is a Garmin Forrunner 945.
Your settings look fine. I had a look at one of your recent runs and tried elevation correction on/off and “off” is better. I am not sure why the results are different to Strava. It is possible Strava is using elevation correction anyway and they have very good elevation data. Or maybe they have improved their GAP model from the one they published?
I don’t know if Strava has updated the GAP. I have tried Auto / Yes / No, and the closest to the result of Strava is setting it to “Yes”. I will try in future releases and will update this post. Thanks for your time’.
I will test and play with it next winter. For flats and downhill it is basically impossible to set pace zones for cross country skiing. Speed and pace varies a lot depending on the snow conditions, from icy and quick to fresh wet snow which is dead slow.
Uphills with at least 4-5% are though not that different for us amateurs in different snow conditions (though still huge difference for elites and pros).
I did fix an issue not long ago (tx @MedTechCD ) where the GAP calculation was including stops but the pace one was not. Now GAP also leaves out stops.
