I have a U that has a sound alarm in it. The shackle is steel it can be the wire. The one I have also goes off with a hard tap. It's a piece of junk. It does not work well. I have a few different cable alarms that trigger if you cut the wire or jiggle them. They false trigger or dont' work well. The nicest one I used for about two years and the switch just wore out, and is not repairable. I also have a bicycle alarm that activates with a remote like a car. It stopped working after about a year. They are all very cheaply made.

The problem is to make a good lock as you suggest and to sell them on the market there has to be something in the price for the retailer, the distrubutor and the manufacturer. The locks would have $50 to $100 added to the price for an existing lock. That probably won't sell well. All these lock makers would have been selling something like that years ago if it would sell.

The technical aspect of that idea is as easy as falling off a log. Making a profit and getting the price right is another thing altogether. There are probably a few here on the forums that might pay$150 or $200 for a lock like that, but that's not enough to keep from loosing your investment.