At a minimum you should put your lock through your frame & the front wheel. This is especially important if you have a quick release wheel, since if you only lock the wheel, the rest of your bicycle can be detached & carried away.
Options for locking the frame & both wheels include:
Lock-Up Tip: Locking both the frame & the front wheel makes breaking your U-lock tougher for thieves, & it helps keep your bike from falling over if it’s bumped.
First, remove items from your bike that can be quickly & easily stolen. These include quick release seats, bags & lights. Next, make sure that you have taken as much slack out of your lock as possible to prevent your bike from tipping & to discourage thieves from prying. Also, some people find that making their bike less attractive is an effective theft deterrent. This can involve riding an older bike or using paint & stickers to make a newer bike appear older.
Don’t give up hope, all is not lost! Stolen bikes are sometimes reclaimed, but in order to greatly increase the chances of your cherished steed returning, you’ll need to do two things:
What, you don’t know your bike’s serial number?
Well now’s the time to find out (if your bike hasn't been stolen!). The serial number is usually located underneath the bottom bracket (that’s where the pedals & crank connect to the frame), but not always. If you can’t find it, your friendly local bike shop will be glad to help you locate it. Record the serial number & put it in a place where you can find it if it’s needed.