Originally Posted by
Scheherezade
I'd imagine just about any shop would have 8 speed cassettes and chains in stock. The vast majority of bikes in the US use an 8 speed width chain.
8sp is still very common in mountain-bike ratios. The options narrow down a lot when you want a road-ratio cassette, which is what this thread's about. Shimano has HG50 and SRAM has PG-850 with suitable ratios for a 105-equipped road bike.