for example, i grease my chains with a product i got at city bikes. i asked the dude at the counter to recommend to me which product to buy, and he pointed out a bottle that he believes works the best for the price. the downside is that it contains a chemical make by DuPont. so i'm supporting DuPont, ugh. are there options (which in the future we might be forced to use) for grease/lube for bikes that aren't petroleum-based? can replacements be made with vegetable-based oils?
manufacturing bike parts involves factories and industrial processes. when i need something replaced on my bike, i go for used parts whenever they're available, so that i avoid that problem, and because they are less expensive. but in a world where bike parts can't be manufactured easily, or become very expensive, there'll be a run on used parts, and eventually they'll start to run short. can welding or casting or die-making or whatever processes are used be replaced by small-scale operations that can be powered more sustainably?
roads, too, could begin to become more difficult to navigate as the funds to fix them dry up, and as heavy machinery becomes more expensive to run. what then? (on a historical note, i've heard that the first asphalt roads in the u.s. were created for bicycles, pre-auto era.)
rubber for tires comes from trees, but they won't grow around here, i don't think. they're tropical, right? can we cheaply/easily reprocess old truck tires for "new" bike tires?
are we going to end up making bikes out of dried bamboo because metal gets too scarce? ;)