I've also had theifs break into my warehouse by dropping thru the ceiling and lowering themselfs into the unit by going up in another unit by mine and crawling across the rafters. Now the place locks down every unit weither occupied or not. So if your garage is in a row of garages, just another way for them to get in..that's why the cable lock helps too.
Bear traps on the floor around your bike might help too...just saying..