older 105 components
I bought my first bike last year, a Trek 1000... it's served me well, but now that I've gotten more into the sport and started racing, I'm looking to upgrade; I've already acquired a nice Tifosi frame and Shimano wheelset second-hand, now I need the parts. A friend is offering me an older ('97/'98) used 8-speed 105 group that appears to be in very good shape, well maintained and all that. My question is how this group compares to todays 8-Speed Sora (which is on my Trek), as well as today's 105. My main reasons for upgrading are for cleaner and more reliable shifting, shifting in the drops, and durability. I'm worried that in 6 years, even the lowest level components (like the Sora on my Trek) have improved beyond the old 105 componets I'm being offered. At the same time, I'm a poor starving college student, I don't have the $2000 for a new racer. Will this old group hold up?
Also, is there a difference beteen S.T.I. and S.I.S.?
Thanks for your help!