Although we've seen a number of bikes with built-in locks lately, the Dutch-made BluLocks bike still manages to bring a fresh approach to the concept. It combines an external chain with a locking mechanism that's located inside the seat tube.
To use it, you start by looping the nylon sleeve-covered hardened steel chain around an adjacent immovable object such as a sign post, then plugging a pin on the free end of that chain into a receptacle in the seat tube. By turning a key in a keyhole in that same tube, the chain is locked in. Turning the key additionally causes the internal mechanism to lock the crank, so pedaling is impossible.
People wishing to steal the bike would then have to either go after the mechanism – which would be quite difficult, and involve wrecking the bike to the point that is was unridable – or they could cut the chain.
Doing the latter would still leave a bit of the chain dangling from the bike, however. Perhaps not a deal-breaker for thieves who are simply looking for a ride, but definitely a deterrent to people hoping to sell the stolen bike. Additionally, they would still be stuck with a bike that they couldn't pedal.
The 11.2-kg (24.7-lb) steel-framed bicycle itself comes in two frame sizes and four color choices, plus it features a flip-flop rear hub – this means that it can be used as a freewheeling single-speed or a fixie.
The BluLocks bike is currently the subject of a Indiegogo campaign, where a pledge of US$399 will get you one. You can see a demo, in the video below.