I bike home from work. At least half the route is within a big greenway near the Salt River. It's one of the great blessings in my life. Dunno if I'm supposed to get spandex or not, but seeing as I've made due with regular shorts for about 45 years now, spandex is probably not on my shopping list.
As far as cardio goes, it's a whole lot kinder than running. And in the summer, biking is cooler than walking.
My knees are slaughtered. I limit the amount of impact I subject them to.
