Some randomness:

- Someone mentioned BB lasting basically forever. Some might, probably higher end cartridge type, but some of the newer proprietary BB[whatever] bearings and especially recently popular outboard bearings will go within a year or two. Upshot is that they are still not too expensive to replace.

- If you're running integrated drop-bar brake/shift levers, make it a habit to replace cable and housing every 2-3 years. Tight spooling within the shifters exacerbate cable wear and breakage and the last thing you want to do is break a cable inside the shifter... This was more a problem with older Shimano systems where the shift cables exited the sides of the hoods toward the centerline of the bike, like current Tiagra; unsure if the same problem exists with under the bar routed systems. In any case, with Shimano and SRAM brake/shift levers (road), there is a definite lifespan -- could be 3-5 years, could be one, could be a decade -- they are non-rebuildable for the most part, and expensive, so consider shifter style when considering purchase.