Why shouldn't I let it warm up while I'm putting on my gear?
Engines warm
drastically faster when under load than when under no load (idling). The evils of idling are
ultra low oil pressure at a time when the oil is at its thickest and doesn't flow very well. That means that right after starting is the point where you have the worst lubrication. By riding you're forcing the oil to move more and provide lubrication to the points that aren't bathed in oil (think heads). Using a good
synthetic oil with a low 'cold' number, such as Shell
Rotella T 5w-40, will mitigate this as much as possible.
The engine also needs a higher concentration of fuel to air at startup, as the atomization of the gasoline is poor in a cold engine. This means that the sides of the cylinders are getting hosed down with gas, which washes off the little lubrication that was there (and isn't being replaced at idle, due to the factors discussed above).
The last, and most important, issue is that you create localized hot spots by idling. The engine does not warm evenly. When a mass of metal is bolted together, as an internal combustion engine is, it heats rapidly in some places and not in others. This makes it more susceptible to warping and seizing/galling, which is where two metal surfaces stick/weld together, then rip apart, leaving both surfaces weakened.
So, take it easy until you can see that the engine is warmed up; then you can ride like your normal squidly self.
