in hiking and bike racing
bicycle
The bicycle.
true
Brakes are meant to have a lot of friction and it's useful.
Yes it is for transportation and it keeps you fit.
The brakes! And the tires (no friction = no traction).
Depends on the traffic situation, not on the vehicle.
Most bicycle owners maintain their own bicycle. But, a bicycle shop may be willing to maintain a bicycle, if you ask.
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.
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.
There is no single most useful Zerg unit; any unit can be useful, useless, or somewhere in between. Where a unit falls is dependent on the current situation. Compare to the game Rock-paper-scissors, where rock is useful against scissors, but useless against paper. Of course the unit relationships are more complicated in the StarCraft games.