Since the highest gears I ever use are in the mid-to-upper 90s, I do not waste valuable combination space on anything over 100 gear-inches. My road bikes have top gears of 49/14, 50/14, and 47/13, and my mountain bike is 48/13, which is equivalent to 50/14 in a road bike.
On the bottom end, I use 42/26 or 38/23 on the road bikes and 28/28 on the mountain bike, although w/ more combinations I could justify dropping the latter to something like 24/28 or 28/32.
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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