I have encountered several above-knee and below-knee amputees who use prosthetics very successfully for bicycling. I think Vietnam veteran Jim Penseyres, Pete's brother, still holds the record for a below-knee amputee in the Race Across AMerica (RAAM). I have heard stories about folks who ride with one leg and no prosthesis, and these completely blow me away, because I have ridden a mile in their shoe(s), so to speak. When I dislocated my left kneecap in the early 1990s (after having also done so in high school in 1967), I removed the left crank and tried riding my mountain bike with one leg. That was one tough workout, and I think I had to use the granny chainring the whole time.
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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