The idea of an alarm on the disc brake is something I like and will have to look into. I recommend searching eBay for the Kryptonite New York Fahgettaboudit Chain with Disc Lock 1415 5' 150cm x 14mm. It'll be about 15 pounds but I have two racks on the RadRover that will hold the weight so I don't have to sling it over my shoulder. The RadRover gets attention wherever it goes. I'm afraid to leave it unattended, but this lock will go along way toward allaying my fears. By the way, no matter how good your bike lock is, you will want to take your battery with you. The lock that holds it in place is cheap, a master key is easy to find on the Internet, and it's a $500 investment.