Mad scientist time here...
Everyone will be familiar with this story... motorbike pulls up at lights, induction loop in the road doesn't detect you, traffic light doesn't change.
Other than the basic principle I don't really know much about these sensors, so have assumed a few things. If I've got anything wrong I'm happy to be corrected.
The first solution that comes up anywhere you looks is adding a magnet to the bottom of your bike... call me skeptical. If a 170kg of mostly steel bike wasn't detected by the loop, I'm dubious, to say the least, as to how much difference a 30 gram magnet on the bottom can possibly make.
My question (and idea depending on the answer) is... Does the sensor detection work based on metal surface area, or on bulk mass?
If it's the former, I wondered if adding a custom outlined shape 0.5mm sheet of steel to the bike's bellypan would be a solution to the problem?
My thinking being this would create a relatively "large" flat metal object, close to the road, similar to the floorpan of a car, while only adding a few hundred grams to the bike and being basically invisible as it's flush with the bottom of the bike.
Or is surface area nothing to the sensor, and it needs more steel mass to activate?
Anyone in the know on these things?