Bicycle theft is, unfortunately, a very common problem. Most bicycle locks are easy to overcome, which makes bike theft a crime of opportunity. Recovering a stolen one is usually improbable, but this DIY GPS tracker could provide the help that you need.

The GPS tracker, designed by Johan, is like Lojack for your bicycle. If the device detects that the bike has moved, it will send a text message and start tracking the GPS location. It will periodically send an update with the current location, so you can track down your stolen bike (with the help of the police).

The key component in this device is a MKR GSM 1400, which is a development board that is capable of sending SMS messages over GSM cellular networks. It uses an ADXL345 three-axis accelerometer to sense when the bike moves. A MKR GPS Shield monitors the unit’s real-time physical location. Power comes from a 4400mAh lipo battery through a SparkFun LiPo Charger Plus board.

Those components are housed within a plastic case that mounts to the bike frame. Johan placed that case underneath his bike lock holder, so it isn’t obvious to would-be thieves. That helps to avoid the possibility of the thief removing the tracker before Johan can recover the bike. If you want to build your own tracker, Johan provides all the schematics and code that you need to tackle the project.