Originally Posted by peterbarson
I know that this is a dumbish question since it's my bike I don't have a proper way to measure.
Anyone know what the diameter of the downtube is on a 1986 world Sport? A german bike shop repairguy is selling Shimano golden Arrow downtube clamp-ons shifters on E-Bay and he says the tube needs to be a diameter of 28.6mm. $8.00 current bid + $6 shipping, is this a good buy. ...
Wrap a piece of paper around your downtube, mark the point of overlap, unroll it, and measure your circumference, preferably in mm. Divide by pi, and you have your diameter. Multiply by 25.4 if you measured the circumference in inches.
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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