The best objects to lock your bike to are streetlamps, street sign posts, bike racks, and steel fence railings. You should not lock to anything loose or easily disassembled or cut. Be sure to remove accessories that are expensive to decrease chance of theft. Avoid locking your bike in the same place multiple days in a row and don’t leave it in any public area unlocked even for a short amount of time. Below is a list of different types of locks and the pros and cons of each.
Heavy chains and padlocks:
Pros: Bomb proof
Cons: Heavy, can’t lock wheels and frame to the same object
Pros: Longer length lets you lock many parts of bike, light weight and easy to carry around
Cons: Can be cut quickly by thieves
Pros: Compact and can be used with a long cable to secure both wheels and frame
Con: Width limits what you can lock to and thin versions can be easily broken