I am more like Swimming, but I like bike too. a bike is my favorite now, I am enjoy Swimming and bike
Swimming is game .... It helps for the physical fitness of players and make a huge stamina which is a very useful for any kind of player in any game
I enjoy biking better than (outdoors on a real bike of course) more than swimming but I think swimming will keep you more fit.
For fitness i suggest you swimming first and after that if you have time take chance for other sports.