That depends on your speed.
Three hours (30/10 = 3).
It really all depends on the speed you are going.
about 2 hours
It is 1.2 miles running or biking. (And it is a great ride).
Biking for 45 minutes will burn 100 calories.
if your speed is 4 miles per hour it takes an hour,at 8mph it takes 30 minutes.
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.
You can't bike to the sun because there's no road. It's roughly 150,000,000 km to the sun. Divide that by your biking speed in km / hour, and you'll have the answer to the question I think you intended to ask (in hours). It will be a LOT of hours.
It's not about the miles, but rather about how hard and how long you're riding. Road biking is a lot about endurance, so between dedicated riders it has to be 2-3 hours or more to "count". If you're not that into biking a sort of general definition of a workout is about one hour at an elevated heart rate.