I'm 53 years old and just wondered if covering 10 miles in 42 minutes is any good? There was just a couple of hills on the route but it was mainly flat surface. My avg speed says 14.3 mph, but I have no idea if this is any good for my age. I am using a Giant Defy 4 Road bike, it's not a Carbon bike and cost around £600 new. What do you reckon? Cheers!