The company I work for provides a really nice fitness center for employees who are so inclined. And for a VERY attractive price, too! I believe it's $10/month.
When I first started at my job, I thought I'd give it a try over the first winter, on the cold and slippery days when bike-riding wasn't so attractive. (Back then, it was $5/month, so I figured that's all I had to lose.)
The fitness center offered Richard-Simmons-style aerobic sweatin' classes. (Not interested.) Weights - both free and weight machines. (Mildly interested.) Lots of various other machines - joggers, rowers, stair-steppers... and stationary bicycles! (Interested!)
The bicycles were what caught my eye. They had several, of various types. Some were simple - the kind where you just twist a knob to set the amount of resistance. But there was a computerized one that would let you program in a "route" to follow, with varying degrees of resistance. Theoretically, sometimes it's like you're climbing a steep hill in difficulty level, and at other times it's like you're coasting down the other side.
So - I tried it.
And - I hated it!
Even on the computer-cycle, with the TV set on (cable news), it was just WAY too tedious and boring.
Compared with riding a bicycle, it was like being a hamster-on-a-treadmill.
I guess I couldn't catch the vision of exercising for "fitness" alone.
Riding a bike, out in the real world, you get the exercise (perhaps not as "concentrated" as at the fitness center, but definitely of value). But in addition, you get the wind blowing in your face (sometimes blasting you like a convection oven, sometimes with winter chill). You get the scenery flowing by, and the ever-changing environment. Often you have that beautiful blue sky overhead. Occasionally there's somebody to greet. There's a need to keep the senses tuned for potential hazards.
I dearly missed all of that stuff, when riding the bike-that-doesn't-move.
That was years ago. Since then, I've seen ads for stationary bikes that are even more sophisticated. Some even include video road courses on a screen in front of the rider. Would it be the same? Even a passable simulation? "Spinning" was the big craze for awhile. That's apparently where several people ride stationary bikes facing each other in a circle, and see who can spin the fastest...? (I never participated. I don't know if it's still popular or not.) None of that stuff attracts me the way a simple bike-ride does.
And besides that... I can start in one place and finish in another, so a bike ride has additional purpose!
Of course, if you're choosing between: 1) Fitness Center, and 2) Sitting on your sofa eating Cheetos and watching "The Biggest Loser," Fitness Center is THE choice!
(One amusing side-note. I believe I signed up in December and January. On January 2nd, I went in and the place was PACKED! Usually it was almost empty. I thought, "Oh, no! All these new people have signed up for exercise as their new-year's resolution!" And thought I'd have to jockey for position from then on! But not to worry - on January 3rd, the place was almost empty again.)