I work out 3-5 times a week. I mainly do free weights and ab routines. Unfortunately, my results have suffered because I rarely do cardio. I'm seeking any input regarding bikes and treadmills: preference, results, recovery time, etc.
@Ryno 2: I'm speaking of results primarily in terms of getting leaner (and building my cardio). My body responds well to free weights but I'm trying to get away from the bulky look.
I have bad knees so I prefer to do the stationary bike. I also take 20 pound weights and do curls as I am riding a long. You can mix it up by doing different types of arm exercises. In addition, to knock out the boredom, I pedal backwards. It takes time to get used to, but it gets easier. I switch off every 5 minutes. Believe me, you'll not think of boredom. Best of luck.
I personally prefer a bike to a treadmill as I find it easier to do (treadmill walking always feels awkward to me somehow) and it's easier on the knees. Stave off boredom by varying your speed and resistance - I think there are even a few Skimble workouts designed for biking, that tell you to bike hard, then slow down, then go hard again, etc. Arm exercises are good too as others suggested. I also like reading or watching tv as I ride, and/or listening to music or an audio book.
I think I also prefer a bike over a treadmill because - I can walk anywhere. If I want to go for a walk, I can go outside, or to the mall if the weather's bad. I don't really need equipment for it. It's a bit more challenging for runners but there are always options. On the other hand, if I want to ride a bike, I need to have a bike. They're not just there in the natural environment. So if I were making a choice of a purchase, that would lean towards the bike.
I am a long time treadmill runner. I have tried the stationary bike but my back eventually hurts. If you're not big into running, you can do quick HIIT workouts on the treadmill and get big results that way. I've created some HIIT workouts for the treadmill based on some workouts I've "borrowed" from the pros. Also, benefit of the treadmill is the famous "runner's high" ... : )