i started riding bikes in philadelphia. it's pretty hilly around there. the local rides went to many hills and were very fun (especially delaware county). lots of variation in speed and effort. now i live in ann arbor MI, and it's pretty flat. i went on my first group ride today, and it was much different. the group held a more consistent (higher) average speed, and there wasn't as much variation in effort. it was almost in a way monotonous. i don't want to come to a conclusion until i do a bunch more rides, but, man, i miss the hills. anyone else encounter this type of situation? any tips on making things a little more interesting? i guess sprints? or intervals while out riding alone, maybe?