This is why one bike lock is never enough in Amsterdam.
The first bike I bought here cost about 50 euro, it was bright blue, with a bike rack on the back and had 5 gears. My Dutch friends thought I was crazy to buy such a pretty bike, it was bound to be stolen. And it was, from a train station outside Amsterdam.
So, with a friend’s help I acquired a new one, for about 15 euros. It was probably “pre-owned”, bike-theft being the most common theft in Amsterdam. It was black and ugly, it rattled and was hell to ride. Within six months it was stolen, from the bike shed at the university. I wasn’t sorry.
So I bought my third bike, second-hand from a reputable dealer, it’s again 5 gears and dark blue. I also bought two bike locks, making a total of three, since there’s already a wheel lock built onto the bike. The new locks are heavy, they probably weigh as much as the bike, and together they cost more then the bike. But hey, I still have the bike.