Originally Posted by
SlimRider
There's one problem with your argument here, Nubcake. Eventually, that limp-a-long bike, is gonna have to get fixed. It can't just limp along forever. According the 2nd Law of Thermodynamics, with increase in time the universe experiences greater entropy. That's why everything deteriorates, given time. The more time, the more chaos!
Ya gotta take the time to apply the energy, and work to get your mechanical system, called
the bike, to operate according to expectations.
That's why you
NEED a spare bike...Just in such a case!
PS.
The Second Law of Thermodynamics demands that the N+1 Rule be obeyed without question! 
The idea is to limp it along until parts show up, not use band-aid fixes for permanent repairs
Even if you do completely trash a wheel or a part that is un-available right away to where you can not keep the bike going you can try scavenging or just walk/take public transit, a cab for a couple days, etc.
You can justify your 2nd (3rd, 4th, 5th, however many you want) bikes however you would like to yourself but telling new commuters the NEED a second bike is only going to discourage many would be commuters. I promise you if I tried telling a customer who came into the shop they need 2 bikes if they want to commute they would either go to another shop or give up the idea of commuting entirely. Hell this isn't even the car free section so take your car for a day or two if you trash the bike beyond repair (again, extremely rare if you keep up with repairs) Although I am liking the creativity in your way of justifying multiple bikes SlimRider