Originally Posted by DonBjr

One quibble... the correction feature on GC and other sites like strava, aren't always correct. It seems they probably go off some topo data for the area rather than the reality of what might be a graded road. This can result in inflated elevation gain numbers if it thinks your going up and down, when the road/trail might have been a steady grade.

I tend to calibrate my barometer off of a gps check of the elevation at the start of a ride and shrug off the rest of the imprecision that might happen if the weather is changing.