Android vs. Garmin altitude data seems like an irrelevant distinction, as Strava keeps and maintains forever the altitude profile of the very first person who rode from A to B, no matter how ridiculous the data. On the route I ride most often, up Tunnel Rd in Oakland, California, it's a climb of about 1000 feet over about 4 miles, depending on where you reckon the start and end, but on the whole length it's just monotonically uphill. There are no down grades. But the Strava data is all over the place. It goes up and down on small scales constantly. It says there's a -47% grade at one point. The profile looks like the business end of a backsaw, when in reality it's just up.
To make any sense of this data requires substantial low-pass filtering over their altitude data. I don't know why Strava doesn't try to clean this up.
To make any sense of this data requires substantial low-pass filtering over their altitude data. I don't know why Strava doesn't try to clean this up.