Bike riding is enjoyable but I'm not sure I'd call it 'fun'. Playing ice hockey is fun, but cycling, particularly racing, involves a lot of time spent suffering. Sprinting is fun, moreso if you win, but mostly road cycling is just pleasant and enjoyable. I agree that mountain biking can be fun if you find a nice flowy track to ride, but I still prefer the satisfaction I get at the end of a ride on the road.

I spend many hours reading as well which I also consider enjoyable and not 'fun'.