So I decided to try to find out just how steep the worst hill of yesterday's ride was. I went over to Map My Ride, and put in a few miles worth of my course near Galena and Bettertown, MD.
MapMyRide said that the whole thing was between -1% grade to 1% grade -- no hills at all.
That, of course, does not square with my memory of events. So I re-entered a route, focusing on just the hill: down Still Pond Rd/292 to the park on Chesapeake Bay, then turn left and pedal like crazy up Ericsson Ave.
That showed a 17% grade, which is a lot more like what my calves remember.
So be careful: MapMyRide seems to show the average slope, but can gloss over the highlights. I don't know how it picks the points between which to calculate the incline, but it can leave out some important details.