I don't have a car yet, still taking lessons

.
Got a bike, and don't go to the gym.
That's not the point though, although in some cases 30 is a tad too much, if they are planning to do 20mph on some main streets, it's a different matter. Usually these bits of road are easy to drive much faster than 30 on... It's kind of silly, someone with a racing bike can go as fast as he want yet cars have to drive slow.