Buy a HealthRider instead of an exercise bike
I'm not precisely sure when we bought the HealthRider exercise machine you can see in the pictures below. I think it was probably around 1993 or 1994 after seeing it and trying it out at a mall.
What attracted us was its obvious simplicity and ruggedness, the comfort, and that it really can provide everything from a short, extremely high intensity workout to a more leisurely long aerobic session.
I don't remember what we paid for it, but I am sure it was more than what they sell for now, so it was not insignificant when you consider that even $300.00 in 1993 dollars is close to $500.00 now (http://www.measuringworth.com/uscompare/)
Not like a stationary bike
Although you could certainly consider a HealthRider as a substitute for a bike, it is really more like a rowing machine in that it works both your arms and your legs. However, unlike a rowing machine, there is little back motion or flexing - your trunk moves up and down. That's very important to my wife, who has disc degeneration issues.
I never liked stationary exercise bikes. I find them quite uncomfortable - I suppose there may be good reasons why an actual bicycle might not have the most comfortable seat, but why can't a stationary bike be comfortable? The HealthRider seat is.
The resistance of every stationary bicycle I have ever used feels "wrong" to me. They are mushy or sticky; certainly they are not at all like riding a real bike. However, I never have used an electromagnetic or generator style bike - these are much more expensive and supposedly provide smoother resistance.
The resistance on the Heathrider is your body weight and your foot positioning. Although additional plate weights can be added, we have never felt the need to do that. I can't imagine anything smoother than this mechanism - it is dead simple and, as noted, very comfortable.
Note that HealthRider offers two models - the HealthRider and the HealthRider 2. The MSRP is the same ($599.00, though they sell for much less), but the "2" has an additional "resistance" bar which apparently has been the cause of dislike with some customers.
My feeling is that simpler is better. I see broken exercise bikes quite often at our gym; admittedly they get abuse they wouldn't suffer at your home, but on the original HealthRider model, there isn't much you could damage with anything short of a sledgehammer.
Well, except the electronics, of course. Our model came with a simple magnetically driven counter that didn't last more than a few months. I replaced it with a cheap egg timer attached with a rubber band as you see in this picture. I actually like that better anyway. Electronic doo-dads that measure calories and all that are fine, but they are just another darn thing that eventually will break. My cheap egg timer replacement will die someday too, but at least it will be easy to replace!
Recent studies suggest that short periods of activity throughout the day are very important for overall health. This machine is ideal for that: I have it in my home office and just hop on for a few minutes frequently throughout the day. I like that it is very close to a full body workout and that I can consciously give more attention to my upper body simply by slacking off with my legs and vice versa. I can use the upper pedals for a very difficult leg set, pull very hard and fast for a quick, high intensity workout, or slow down for a longer period.
There isn't any. We've had this rider almost twenty years now and have never done anything but dust it now and then. There's nothing to oil, nothing to grease. If you did manage to somehow break some part of this, I imagine you could run it down to a local welding shop to get it fixed! I don't know if that's still true with the newer models, but I suspect that it is.
My wife and I heartily recommend this. Simple, rugged and a good workout. You'll probably pay half of what we did, and even less in real dollars, and you probably can't ever wear it out.
If you should ever happen to see one of these at a yard sale, snag it - you will be getting an incredible bargain.