A motorcycle alarm is very useful. They have numerous features. I had a scorpio with a 2 way remote that let me know the alarm was going off if I was within a 1/2 mile of my bike. This proved very useful one night while it was parked outside my hotel room up at Americade. I had a motion sensor under the rider seat, and an ignition kill. I set the motion sensor so it would warn twice and then go off if anyone was right next to the bike or tried to throw a leg over it. The ignition kill will disable the ignition if the alarm goes off, so no one can hot wire it. I always felt a little better about parking the bike with an alarm on it. Now we all know that if someone really wants your bike, they will take it. The alarm acted as a great deterrent. I don't like to let the bike out of my sight, but it is nice to be warned by the remote that there is someone close to it.How does a motorcycle alarm work? Are they very useful? Thanks!