This practice is to mainly avoid muscle cramping that can occur when strenuous activity is immediately followed by rest. Most professionals refer to this as "cooling down".
Only your doctor can answer that.
Talking about riding speeds and riding distances on a stationary bike is rather pointless because the bike isn't going anywhere, at any speed. If you're riding for exercise, count the time instead.
Stationary Bike was created in 2003.
Since a stationary bike doesn't move, there's no way it can travel 20 miles. Now, if you're asking how long it would take to ride twenty miles on a bicycle, it depends on speed, wind, and other factors. Typically a bike maximum speed is about 20 miles per hour. So it would take about an hour to ride 20 miles on a REGULAR moving bicycle.
A spinning bike, a stationary bike or an exercise bike.
A heavy duty stationary bike cost 17,000 php here in the philippines.
Entirely pointless question as there aren't any steps in bike riding, and a stationary bike doesn't go anywhere. But making some rough comparisons to real life riding a 20 mile ride under average conditions can be anywhere between 45 minutes and one hour 20 minutes, depending on the rider, bike and course. A well accepted recommendation states that the cranks should turn at a rate of 80-100 turns/minute, which gives you around 6000 turns for the ride.
A stationary bike is good for American football because it helps the players in their workout.
You can get a stationary bike at any of these following places I have found for you to have a look at. Wal-Mart should have some, best buy, Lowe's and sears has a few. I hope these places help you as you look for a stationary bike.
No, it is illegal to ride a dirt bike on the street but you can ride it on a trail or dirt bike track.
That's all down to the skills of the rider. There's even the art of trackstanding, where you stay on the bike while remaining pretty much stationary.