I'm 71, 5'5, weigh 135lbs. I ride the same course every day because it's safer on the best roads with almost all right turns. 7 days a week at 51 miles keeps me fit and by the way I leave most people in any age group eating my dust. I almost never get flats unless I run over something sharp. I can breeze up steep hills and though fast twitch muscles are not what they used to be I can hold a respectable steady pace forever. My bike is set-up by professionals and it is the right size.