Your stats in VeloViewer are only as good as the data that is passed in from Strava, and around 1.5% (based on sample data I had a couple of months ago) of Strava segments seem to have bad data associated with them. The 2 main culprits are dodgy elevation data and non-matching distance data.
This isn’t entirely Strava’s fault although I believe there are ways that they could clear up the majority of these things automatically. But for the time being it is up to us, the Strava community, to tidy it up the best we can which will also result in much more accurate stats in VeloViewer.
Bad Elevation Data
This is the most common type of problem that effects your VAM and Relative Power stats often giving ludicrously high values. Typically this is down to the GPS device used for the created segment getting confused and not recording the elevations accurately. On some segments this can be hard to avoid due to severe gradients mixed with tree cover resulting in trouble picking up enough satellites but it usually more of an issue with the device being used for tracking, some are just much better than others.
When looking at a suspect segment in Strava then the tell-tale signs for bad elevation data are:
- Sudden steps in elevation.
- Gradients that just don’t match the lie of the land (see image below).
Comparing the elevation profile with the contours should give you enough info to tell if there is a probelm. I personally find the contours shown on VeloViewer’s Segment Detail page clearer to see than the Google view on Strava.
I’m not sure if this is still the case but historically Strava have automatically created segments where one doesn’t already exist for categorised climbs. Unfortunately they don’t check to make sure that this “categorised climb” isn’t in fact a flat section of road on which someone’s confused iPhone suddenly worked out how high it was and jumping it’s elevation by 100m vertically. I can’t believe that the user involved manually created these segments as they are most often on completely random bits of road that would be of no use as a segment in their own right.
If Strava could run a quick double check these automatically created segments to make sure the min/max elevation points are correct then that should avoid 95% of the problem. They only need check segments where the resulting KOM’s VAM is crazy high to cut down the processing a bit. I’m sure an automated check could also be done on mass to correct elevation data for all segments with a KOM VAM greater than say 2300 (or at least queue them up for correction when the servers aren’t so busy).
How to correct your segment’s bad elevation data
- Visit the Strava Support Site.
- Login (if not already logged in).
- “SUBMIT A REQUEST”.
- Pick “Segments :: Bad data” from the “I need help with” list.
- Add a catchy subject like “Incorrect elevation data”.
- Paste each offending Strava segment url into the description box (e.g. http://app.strava.com/segments/808884, if you’ve navigated to the segment in the context of a ride then hit the “Go to segment page »” link at the top of the map). Worth adding all your dodgy segments in one support request to save extra admin hassle at Strava.
- Say a big THANK YOU to the support staff and hit the “Submit” button.
- Submit the request.
The support staff are happy to do this and usually complete them in a day or two.
When they’ve been updated then navigate to the Segment Details page for each segment concerned in VeloViewer and click the “Update segment details” link at the bottom right of the page.
Bad Distance Data
Less common this one but does still crop up from time-to-time. Historically this often occurred when looping segments were created with the start and finish points being very close together. The segment would be 20km long but people were recording times of 10 seconds giving remarkable average speeds and VAM/RPs:
These segments should probably just be flagged or create a support request to have them deleted.
These days Strava ensure that at least 75% of your route matches that of the segment so hopefully no new segments like this will be showing up but you potentially have some residual segments that were matched prior to this feature being implemented by Strava.
Which of My Segments Have Bad Data?
If you check out your Summary page then your Climb Stats table will give you a good idea if any of your categorised climb segments have bad elevation data. Just look for very high (>2000) VAM values. An exclamation mark is shown next to any values that warrant investigation:
Clicking on the Max VAM or Relative Power values will take you straight to the Segment Details page.
Another, and more thorough way, is to go to your segment list and order by the KOM Relative Power column. Any segments with a KOM Relative Power great than 7 Watts/Kg probably needs investigating. These will either be due to bad elevation/distance data or due to the KOM being from a car journey, in which case you should flag their ride.
If you’ve not tidied up your data before then you might need to set aside an evening going through your suspect segments and providing the list to Strava Support but once it’s done then your data is going to be much better on VeloViewer as well as on Strava and you can be content in the knowledge that you’ve done a little bit of good in the Strava community improving some of the data for everyone else as well as yourself.