What intersections does the Veloloop work on?
It works on intersections that are controlled by inductive loop sensors (ILS). This includes intersections that are controlled by both ILS and video cameras, but of course not intersections that are controlled ONLY by video.

How does it work?
Inductive loop sensors operate in the 10 to 200 KHz frequency range, minus a protected band around 90-100KHz. The Veloloop scans this frequency range for the sensor's signal. When it finds a signal, the Veloloop responds by transmitting a signal very close to the original frequency to almost cancel out the original signal. The resulting change in the sensor's signal is detected, so the traffic light controller knows that "car" is waiting.

The aluminum loop on the bicycle version of the Veloloop is both the transmitting and the receiving antenna. The black box holds the electronics and the two AAA batteries. A spoke magnet on the bike's wheel tells the electronics when the bike has stopped, so the Veloloop knows to start scanning for an inductive loop sensor. A red LED flashes as the Veloloop scans. If it finds a sensor, the red led goes solid as it transmits. If it does not find a sensor (like when you park your bike) the scanning times out after 20 seconds.

Is it legal?
Yes. The FCC publishes rules for unlicensed transmitters (Part 15) in the United States, which both the inductive loop sensors and the Veloloop follow. We have not yet investigated rules for other countries, so we will be selling the Veloloop only in the U.S. until probably 2016 when we investigate other countries' rules.

Is it compatible with my Garmin cadence/power meter?
Yes. In fact, you can use a single spoke magnet for the Garmin and the Veloloop.