I am dusting off my hybrid for the first time since college 10+ years ago. I'm riding with a friend who is also just getting back into riding. He road in the MS 150 in Kansas City several years ago. He uses a cadence computer to help him choose his proper gear. He suggested I might want to invest in the Cat Eye Astrale 8 to help me with my cadence. Other knowledgeable people have suggested getting a HRM if I had to choose between the two. Which would be better? We are recreational riders getting older just trying to stay in shape. Any suggestions would be helpful. Thanks.