I don't have a garmin, but use a Sigma bike computer. Your numbers, both in terms of calories burned and avg heart rate seem low to me, but maybe my signma is giving me higher numbers than actual. I just returned from a 20 mile ride, monderately hilly (I don't know the elevation gain, but I was huffing and puffing up a couple of the hills) , avg speed 15 mph - my avg heart rate was 144 and calories used 1159. I'm impressed with the length of your rides and your avg speed over those distances