Originally Posted by
PoManBiker
Is the chain ring likely to be compatible with modern pieces?
That all depends on your bolt circle diameter -- start with the SheldonBrown.com glossary definition for BCD. If you have a modern road standard double with a 130mm BCD, you can go as low as 38 teeth, which you should have no trouble finding. With a 110mm BCD, which was typically used on mountain bikes of your era, you can drop to 34 teeth, or to 24 if you have a triple with a smaller granny bolt circle.
If either of your derailleurs cannot handle the increased difference in chainring size, consider replacing both chainrings with smaller ones. On Capo #1, instead of a typical ca. 1980 52-42 combo, I use 47-38, which lowers all gear ratios by 10% for a given cogset.
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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