please explain the process for truing up the elevation readings. I'm getting some really strange readings at the start of my ride then I get results that at least seem to be correct for relative elevation changes

This needs to be done. I live in the mile high city and looks like I'm running or biking on a flat road. And there are very few flat roads in the mountains.

In truing up, we can also graph data by relative high and low points of the workout, rather than graphing relative to 0

It seems sometimes the devices get strange elevation readings during a workout. Use a service like Google Maps to true up the elevation stats.