Originally Posted by
seblastian
I have been wondering, has anyone heard of a GPS bicycle security system? Since animals, phones, and all sorts of things are tracked by GPS why not my bike????

Yes, there are some, but they have several issues. Here's one example (note that the reviews are not very favorable):
http://www.amazon.com/Zoombak-ZMBK34.../dp/B001EJP3CG
There's also a system available only to law enforcement for them to use in setting up 'bait bikes' for sting operations.
http://www.pegtech.com/sbts.htm
Main issues:
1) A GPS alone doesn't transmit any information, so you also need a cellular phone or other system in combination with the GPS - the two systems can be built into the same device
2) Both the GPS and the transmitter (cellular or other) require power - so you'd need to keep a battery charged up
3) The GPS and transmitter need antennas that aren't blocked by metal parts of the bike. Although these can be pretty small they would still probably be noticeable by a thief who is looking for them. Might not be an issue yet while such tracking is rare, but I'd expect the thieves to catch on if such devices become common.
4) GPS doesn't work well inside buildings with metal roofing or other materials that block microwave signals.