Join Date: Jul 2000
Bikes: 1959 Capo; 1980 Peugeot PKN-10; 1981 Bianchi; 1988 Schwinn KOM-10;
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 141 Post(s)
Originally posted by mgagnonlv
I suggest you visit http://www.sheldonbrown.com/gears
For "Gear Units" select either "Gear Inches" (U.S. notation) or "Meters Development" (European Notation). With either choice, Crank length isn't important
1) Yes, the U.S. and metric notations differ not only by unit conversions (2.54000 cm / inch, etc.), but also by the factor of pi built into the metric units, which do actually tell you how far you travel per pedal revolution. In contrast, the U.S. system tells you how your gearing compares to that of a fixed-gear penny-farthing bicycle with a drive wheel of a given diameter.
2) Although crank length has nothing to do with gear ratio and distance per pedal revolution, it directly affects how much force you must apply on the pedals, and how far your feet move per pedal revolution. This is why Sheldon likes the concept of "gain ratio," which incorporates crank length, wheel diameter, and gear tooth ratio.
"Early to bed, early to rise. Work like hell, and advertise." -- George Stahlman
Capo [dschaw'-poe]: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger, S/N 42624
Peugeot: 1970 UO-8, S/N 0010468
Bianchi: 1981 Campione d'Italia, S/N 1.M9914
Schwinn: 1988 Project KOM-10, S/N F804069