In regards to the alarm. Cars have these alarms and still get nicked. When it comes to stealing the bike, people have done tests to see if people if fact even care. Turns out they dont and will just walk by as a person saws off a lock and in one case even with a mobile chainsaw.
That brings me onto another thing were there is a joke about the police who do nothing about people stealing their bikes.
Man: Police operator, there is a man nicking my bike
P: Sorry but we have no units in the area
M: What do you mean , hes stealing my bike
P: I'm sorry we don't have the resources and no units are in this area.
M: I guess I will have to solve this myself
P: Please don't interfere as you may be hurt
M: Its ok I have a gun, I will just shoot him
P: You have a what?
M: I have a gun. I'm going out side. I'm going to shoot this farker.
4mins later 4 police cars with 2 armed response units turn up outside and get the robber and the man.
Man: I thought you said you had no units in the area.