It seems trivial, being a bike mechanic. But the inner workings of so simple a machine still baffle many people who use them.
Some changes represent improvement. Some changes just seem to spring from the inner circle of cycling's need to make things confusing enough to keep the outer circle from figuring it out. I stand between the circles, as I always have, observing the inner and reaching to the outer. I try to figure out what of the secret knowledge is really worth learning and what is best left to the obsessed.
My decisions save lives. I could have died or suffered permanent injury when I was eight, because my handlebars came loose after my bike had been manhandled by a moving-truck driver. I remember that as I go over the details of bent, dirty, disregarded children's bikes, mere toys on which a child's life depends. Sure, they can still crash or get crushed by a careless adult, but at least the machine was in the best shape it could be.
Who cares that I know so many ways a bike tire could get a flat? It's not great statesmanship or an intricate point of law. It does not fight terrorism or cure disease. But it will matter to you if I found the source of your chronic flat tires, so you don't have to stop four times in a 60-mile ride or have the front tire suddenly go soft as you're bombing down a mountain grade at 45.
It's nothing, what I do. I'm nothing. I'm the air in your tires.
Do without me.