Originally Posted by smarkinson

So there is a bit of a difference for the rides to and from the hill so I wanted to figure out what was the reason for this. I took the raw data from the Garmin fit file (I loaded the file into Golden Cheetah which lets you look at the actual ride data and it is a simple matter to copy the elevation data) and put it into a spreadsheet. I then added each increase in elevation and summed these. These totals matched the Garmin figures.

The next thing I did was download the GPX file from Strava which has the elevation corrected data. I took that data and put it into the spreadsheet to compare it against the Garmin data. For the ride back home the sum of the elevation points was 190m (versus 196m for the Garmin data).

It's interesting looking at the individual entries for the Garmin as the minimum elevation gain is 0.4m (in fact the Garmin data was only one of three possible values, either 0, 0.4m or 0.6m) while the Strava elevation correction data would have variations as low as 0.1m.