RB repair advice needed.
I have to change the cable that controls my rear derailleur, which are STI Sora 8 speed shifters. The RD looks pretty worn too (approx. 10k miles on the bike).
1. Where can I get the "exact cable" that fits this STI 8-speed shifter?
2. The originall factory setup is a Sora RD with a long cage matched to a triple chainweel and 8 speed cassette.
(a) Can I upgrade to a Tiagra 4500 GS Triple 9-speed RD?
(b) If so, will it work with my existing 8 speed cassette since it's for a 9-speed?
3. If memory serves, when I feed the new cable through the STI shifter do I
(a) Click the "button shifter" to its lowest setting in correlation with the chain being on the smallest chainweel and smallest cassette cog?
(b) If so, do I then fasten the cable so there's no play in it?
(c) Do I then adjust the top limit screw to align the low cog and bottom limit screw to align the high cog?
Anything else I need to know to adjust the gears?