You need a u lock plus something else another u lock a cable lock locking skewers etc.
How to properly lock a bike with a cable lock.
Make sure what you lock your bike to cannot be cut.
Secure by passing the free end of the cable through the loop.
The less room inside of the u lock or chain the more difficult it will be for thieves to use their tools.
Make your bike ugly.
Use multiple locking mechanisms.
Secure the front wheel using one end of the cable by pushing it through.
Lock according to value frame first then back wheel and finally front wheel.
A bicycle locked using a chain and u lock make sure the lock is far away from the ground if the lock is close to the ground the thief can use the ground as a base to keep the lock and hammer to smash the lock.
Cable locks are available for sale but should only be a secondary security measure.
Cutting a cable lock is so easy and quick that it s possible in broad daylight with people nearby.
Another very popular technique is to use one decent lock and a cable.
Therefore always keep the lock away from the ground.
Push a loop of the cable through the rails of your saddle.
Attach a u lock or chain around the rear wheel the frame and the bike rack as above.
Secure the saddle with a long cable.
Get a tight fit.
Then push one end of the cable through the front wheel pass one loop through the other loop and secure the first loop to the main lock.
Use a d lock on rear wheel through frame and an immovable object.