A friend of mine has a 2005 (I think) Specialized Allez which has never run smoothly. He is constantly dropping gears on his rear derailer which his mechanic has not been able to remedy. He has been told that the issue is the chain and that the type he needs is not available. This does not seem right to me at all even with my modest mechanical prowess. I'm wondering if it is a compatibility issue of some sort.
This is what he is running....
RD: Tiagra RD-4000 (marked 9sp)
Cassette: 8 speed (21t/24t 32H)
Chain: Sram PC58
Crank: Specialized Triple
Shifter: Sora ST-3300
Im thinking the shifters should be the only compatibility issue but I don't know how to tell if they are 7 or 8 speed, i'm assuming 8 but i'm not sure.
Thanks for your input.