As an avid cyclist and also a golfer, the biggest difference for me is the time commitment. A bike ride can be any length and my rides can be squeezed into the time available. To play a round of 18 holes is about a six hour commitment when you add in the drive to and from the course and warm up on the range. A three hour bike ride is a lot easier to sell to the home front on a Saturday morning than a six hour round of golf. Even a century can be completed in about the same time, although I'm not good for much when it's done. And for me, cycling has been way cheaper than golf and I even make my own clubs. Whether it's dollars or spousal stress, cycling wins hands down.