Speed and distance conversions are very easy -- for most purposes, one can simply apply a 3:5 or, better, a 5:8 ratio, since 3.1mi is pretty close to 5km. Interestingly, a 1km x 1mi rectangle is a good approximation of a "golden" rectangle, which has proportions of 0.618:1 = 1:1.618.
For nuts and bolts, 11mm = 7/16", 16mm = 5/8", and 35mm = 1-3/8".
Bicycles and American Cars continue to be fascinating hybrids of metric and English threads and diameters.
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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