I love my fixies and for what I use them for(Riding on ice and snow in winter )they are far safer than a single speed that coasts.You just have to be mindful of what you are riding . As for getting a shoelace caught and ending up under a car? Use a chaingaurd .You can run brakes on a fixie if you want extra braking.Once you get used to braking by ******ing the pedals you may find you barely use them.I plan on having the best of both. I have a single speed that coasts and an extra rear wheel dished for a 6 speed freewheel. I shall remove the freewheel add a fixed cog I recieved today , and secure it with loctite red or blue( i want to try blue and see how it works ,red is very permanent unless you heat it to 260 degrees Fahrenheit)When winter comes i will simply have the wheels switched out. The bike was originally a 6 speed but it has horizontal dropouts.Mr Cheung may want to design his bike as a ss but with the rear triangle spaced so that a flip flop hub can later be fitted.In this fashion the bike can be run as fixed or freewheel.Twenty inch wheels make doing so easier as gearing options are more readily available and less expensive.