Is it possible someone planted a bomb in my bottom bracket?
It's making a ticking sound... mainly just under load, when pressure is applied on the pedals. I know enough to know this is likely coming from the bottom bracket, and indicates it needs servicing... tightening? Problem is, according to Bikepedia, my 2007 Giant Cypress DX has a cartridge bracket. I understand these are not serviceable. So as it's probably going to be an expensive fix (to replace the cartridge), I'm wondering if it'd be okay to tolerate the ticking, until the cartridge gives out, or do I risk damaging other parts in the area of the bottom bracket, if I don't deal with the ticking? (Which I guess might be a loosening of the crank arm, or something along those lines).
Ticking from the BB is usually with the interface between the BB-shell threads and BB threads, not the BB cartridge itself. There are so many other joints that can cause squeaks from down there that can be confused with the BB:
The actual TYPE of tick noise is often a clue as what the actual problem is. However, unless you've got enough experience to differentiate the difference between a pedal-thread tick versus a BB-bearing tick, that won't help you.