I think STI conversion is rarely, if ever, worth the expense or the hassle. One can cost-effectively get 18 speeds with a triple chainring and a 6-speed freewheel, 14 with a 2x7 setup, or 21 with a 3x7, often for only the cost of the freewheel itself, or perhaps that plus a chainring, long stack bolts, and a longer BB spindle. How many gear ratios do you really want or require?
If you don't like reaching down between your knees, get a set of barcons.
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"Far and away the best prize that life offers is the chance to work hard at work worth doing." --Theodore Roosevelt
Capo: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger (2), S/N 42624, 42597
Carlton: 1962 Franco Suisse, S/N K7911
Peugeot: 1970 UO-8, S/N 0010468
Bianchi: 1982 Campione d'Italia, S/N 1.M9914
Schwinn: 1988 Project KOM-10, S/N F804069