Around here a cyclist generally can not trigger a light. So I usually treat them as stop signs. I do not blow red lights if a motorist is there to trigger the light. Also I make VERY SURE that I can cross the road with a wide margin of safety.
Insensitivity of loop detectors is a very serious problem in some cities. If you routinely encounter a non-triggerable traffic signal in your town, be sure to report it to your traffic engineering department, and escalate to the city council if you don't get satisfaction. We all need to raise our collective voices.
I can generally trigger an inductive loop detector, provided that I can see the cut in the pavement. My problem is that one of our local major roads was recently repaved, rendering the detector invisible. If I do not put one, preferably both, rims right on top of the detector, I cannot trigger the light -- there is very little room for lateral positioning error.
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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