This was my first weekend with a GPS. Day 1 was a wash because I didn't set the wheel size to automatic and wrongly set the size to 700.

Day 2 went well and I gathered some nice baseline data. But after loading it to Garmin Connect, RWGPS, and Strava I see different values for a lot of the means--HR, calories, elevation. . . Why would that happen? Don't these sites all take the data from the GPS unit?

(Uploading to 3 sites isn't my plan to go forward, I'm just trying them out to see which I like best.)

check out this

https://forums.garmin.com/showthread...nt-than-Garmin

Thanks, Kleng. I got a response from RWGPS basically affirming that each system uses its own calorie calculation. She did say that as they gather data from users with power meters (I'm not one), they are fine tuning their equations.
For now, I'm going with RWGPS as my default, but still uploading data to Garmen Connect.