My father picked up this gadget and suggested it would be good for my bike.
http://www.usa.philips.com/c/App-enhanced-accessories/for-iphone-5-4s-the-new-ipad-aea1000_00/prd/en/
Though he is right, I don't have an iPhone. Basically, its a fob you attach to an item, and it sounds an alarm on...