The only place I get honked somewhat regularly is on Pacific Coast Highway 101 through downtown Encinitas, where I take the center of the right lane because the speed limit is only 30mph / 50kph and because it is narrow and bounded by parked cars, diagonal in some blocks, parallel in others. I like the idea of giving a friendly wave back, which is a much more mature response than my usual instinct.
As a recent convert to mirrors (CycleAware helmet mount), I concur that they are somewhat useful.
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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