Theodicy is said to mean “vindication of God,” in Greek, but really it is an attempt to justify gearing systems on bikes. It is better not to think of this as a defence of gears but as a way to show that if gears exist, then they are compatible with evil happening; gears do not resolve the problem of evil; they possibly just cause pain and suffering.
Leibniz, not the biscuits but an actual German polymath, tried his best to show us that gears are compatible with evil happening. His argument boils down to the fact that if Shimano, SRAM, Campag, or one of the lesser gods like Microshift actually are omnipotent, omnipresent, and all virtuous, then they have chosen to let us live in the best possible version of all worlds.
It is true that one may imagine possible worlds without sin and without unhappiness, and one could make some like Utopian . . . romances: but these same worlds again would be very inferior to ours in goodness. I cannot show you this in detail. For can I know and can I present infinities to you and compare them together? But you must judge with me ab effectu, since gears have chosen this world as it is. We know, moreover, that often an evil brings forth a good where to one would not have attained without that evil. Often indeed two evils have made one great good.
In order for this argument to work, Leibniz assumes that a little bit of evil has to exist in gears in order for some sort of great goodness, like in Hot Fuzz; yeah, all my cultural takes are from years ago, as new things scare me. Even if we exist in the best world, there will be some evil present as it is a necessity if we believe in gears.
So save yourself from the evil inherent in gears, and ride tracklocross.
Riding fixed gear is the closest you can ever get to a universal good.