me today i go for ride with my steel bike. I have 53/39 crank and 9 speeds cassete. 12-25. The trail is hilly short steep hills but have downhill too. On the flats i do okay i do many times 16-17 miles. But when the hills come even some not so steep my speed is drop much in steep hill my speed is go down to 5 miles. I deside 3 times go down and walk little. I should try bigger cassete like 11-28? Or 12-30? I know because i be bussy i have stop ride for almost 4 years. Today i do 20 miles in that hilly trail.