No. It's not useful when you're destination is 10 hours away IN A CAR. it's also not useful when you're trying to unlock or lock a door.
bicycle
Brakes are meant to have a lot of friction and it's useful.
Yes it is for transportation and it keeps you fit.
The bicycle.
in hiking and bike racing
The brakes! And the tires (no friction = no traction).
Because it looked fun and useful, so they brought some.
The "bi" in bicycle means two. If it had one it would be a unicycle which is harder to ride and not as useful. If it had three it would be a tricycle and not handle as well.
One can buy high pressure bicycle pumps online. Some of the useful websites are Amazon, eBay, Lezyne, Halfords, Blue Sky Cycling, Sears and Bicycle store.
You can always ride a bicycle, regardless of your driving license status.
Racing because friction slows you down but you need to go fast.
It is always useful to know about factors and multiples.