Suggest the state gov build a bike shed (2 minute task online) at your local train station. Secure bike parking is the best way to encourage commuting by bike and prevent theft. Opal-activated sheds are a successful existing system that we should expand to all stations.
D-locks are a must for locking up your bike. Thieves wont bother with angle grinders unless it is a very expensive bike. Spend at least $60 on one of these, but the best locks are advised here.
Hexlox is a tiny device that locks into bolts to block an allen key. This prevents parts theft – allowing you to chain your bike up at town and train. It has a unique key to remove it. Around $18 each, half a dozen could be used for handlebars, saddle, brake calipers, derailleur. (Other devices below for wheels, seatpost)
Sign up to PropertyVault and register your bike on the website (free)
You mainly need to add the bike’s serial number, shown under the frame. You should write this number down regardless – the police require it in the event of a theft. The site will prompt you to also add some photos.
Loud alarms are also great to prevent theft. Seatpost alarms come with a remote just like for your garage door. Disc lock alarms have the added security of being a lock.
Cheap Anti-Theft Skewers for your wheels, and security bolts for your seat are also great to permit you to chain up in public without worrying about theft of parts. It comes with a special tool to take the wheel on/off. You probably have quick-lever skewers which mean your wheels are easily stolen if you want to park your bike at the shops, beach, train station.
Apple Airtag is great, but won’t stop seasoned thieves, as it has alerting technology designed to prevent people being tracked. Get a hidden airtag holder for your bike, with anti-theft bolts, to catch the less sophisticated criminals. Alert the police of the bikes location.