Trouble is, if it's a magnetic sensor vs. the new optical ones, and you don't have a steel frame, there truly is nothing they can do (short of spending the however many tens of thousands it would be to go to an optical sensor).

When I rode steel, I always found that a hand's breadth to the right of the oil slick would trigger the sensor 9 times out of 10. You don't want to be on the curb in traffic anyway