http://www.gumtree.com.au/s-ad/maroubra/bicycles/trek-1200-vintage-road-bike-56cm-frame/1122341785Looking at this trek 1200. Would it be difficult to put STIs on this thing? A 90s 105 7 speed would have a 126mm rear hub right? So I wouldn't be able to upgrade to an 8-10 cassette in future?