Will the same hub also accept a 6 speed cassette? Will I need a spacer? Will it fit 8, or is that for 130mm-spaced frames?
Also, if I'm replacing the cassette, chain, and chainrings, should I also replace the rear mech's jockey wheels?
6-speed Uniglide cassette will fit, 8-speed won't. No extra spacers required, the 7-speed was a narrower spacing to fit 7 sprockets in the space previously occupied by 6.
You don't need to replace jockey wheels unless they are severely shagged out, somewhat worn jockey wheels won't have a negative impact on the new chain in the way that worn sprockets and chainrings will.
6-speed Uniglide cassette will fit, 8-speed won't. No extra spacers required, the 7-speed was a narrower spacing to fit 7 sprockets in the space previously occupied by 6.
You don't need to replace jockey wheels unless they are severely shagged out, somewhat worn jockey wheels won't have a negative impact on the new chain in the way that worn sprockets and chainrings will.