When I lived in west Los Angeles and attended UCLA, I carried a big case-hardened steel chain with an Abus diskus or other heavy-duty lock. When my son attended high school, I got him a Kryptonite lock for his mountain bike. Since I live in an extremely low-crime area and leave the bike unattended only briefly, I use a basic lightweight cable with my Abus lock, substituting a heavy cable for visits to UCSD.
The only bike which gets left unattended for any appreciable length of time is the UO-8 beater. Fortunately, every one of my bikes is unique, which could help with identification and recovery, but which may or may not be a deterrent.
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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