Bike folding locks
Folding locks are both effective (reinforced steel) and practical since they are easy to transport once folded. Compact and light, they can be an alternative to the U but do not compete as much in terms of security. They also impress with their storage rack that can be fixed to the bike frame.
ABUS and KRYPTONITE offer you many models.
For more advice, we refer you to our guide: How to choose your bike lock?