Kryptonite Kryptolok Series 2 vs Abus Bordo 6000

This u-lock can work well in low-risk situations, or as a secondary lock to secure your wheels or seat.

There is an included cable with the U Lock, that allows you to secure the other bike wheel (not locked with the U Lock itself), or the seat. This is great for city riders who have quick release wheels, as an unlocked wheel makes for easy theft.

There is an included mount for the U Lock, which allows for one to easily transport the lock with the bike with no further equipment needed.

The Bordo 6000 can be wrapped around a wide variety of objects, since the shape is relatively malleable. U-locks have a rigid 'u' shape, which you cannot bend to suit the object you're trying to lock on to.

This folding lock is a great alternative to u-locks and chain locks of the same security category. If your security risk is medium or low, for example, you have a cheap bike, or you only ever leave it in the hall of your apartment building, the Bordo 6000 will do the job.

Still not light, but a lot lighter than most of the chains and U-locks (like Abus Granite).

As the name suggests, the folding lock folds into a compact bundle, which you can just attach to your bike using the holder it comes with. It's lighter than chain locks, so you won't be carrying as much extra weight with you.