Forget about the bike and parts, this winter I was out on a ride and started adding up the cost of , helmet, face mask, lobster gloves, 3 layers of various stuff, cycling jacket, shorts, leg warmers, tights, booties, shoes, socks. Man-o-man, I'm glad I wear the stuff until it rots off (just parted with some BellWeather winter tights that I've been using for 15 years every winter). I wait until the end of a season and buy the fairly good stuff that is on clearance and use it the following season and wear it until it either falls off or my wife spies it in the wash and gives it the heave-ho.
I think clothes can go on the straight-line method and let's try the double-decling balance on the bike and figure out a useful life for the parts, ah the heck with it, let's just enjoy the fact we can ride.