Published by marco on
People put so much stock in the records and trophies and numbers available on Strava, but it just seems so unreliable.
For example, I’d done a long ride a couple of weeks ago: about 140km with 2350m of climbing in just under six hours. Strava “estimated” my average wattage at about 144w.[1] A buddy of mine saw this and went out for one of his own a couple of days later, putting up about 150km with 2350m in about 6:15. My buddy went faster and farther, weighs at least 6-8 kilos more than me and Strava still “estimated” his average wattage at 131w.
I thought this was wrong enough that I scrolled through the segments on his ride, which looked mostly normal (I honestly haven’t tried to figure out how Strava averages the estimated watts), until I came across this segment:
I’ve seen segments before where Strava has literally no problem with a 1km segment marked at 11% average incline but that I’ve managed at a cool 30km/h—about 3x faster than I would be able to climb something like that, Strava chirpily informs me that I put up 2900+ VAM[2] at I don’t even remember how many hundreds of watts. This feat is flatly impossible for almost any rider, but the segment somehow spends years in Strava’s database without being flagged.[3]
Still, this is the first time I’ve seen Strava estimate 805w on a descent, which my friend managed with absolute aplomb at a cool and calm 106bpm heart-rate.[4] Not bad for an old guy. :-)
The following segment shows that Strava is technically correct when it says that this was the second-fastest time (it considers a more recent tie to be inferior, which is fine, I guess), but it’s positively convinced that my PR is still 33s, although it hasn’t been that since March of last year. How long is this data cached?
I recently bombed a local descent right near my house and thought I’d done quite well. Strava told me I’d gotten my third-best time, which is correct by their calculations, as I’d tied my second-best time, as shown below.
However, if I switch to the “I’m Following” list, I see my PR as the fourth-best time in the list, a full 10 seconds slower than my real PR.
On the left-hand side, Strava is showing my time for the current ride, which is four seconds faster than the PR it’s showing on the right-hand side.
I just see these things because I’m an engineer and am sensitive to odd numbers (which usually indicate a bug in software I’ve written). It may be that Strava’s confused because I only show numbers to users that follow me (rather than to all users) and maybe their caching is not optimized for this situation. This happens a lot, though.