Are there any bluetooth speed sensor with data logging ability? I use my bike mostly for getting around town. First I used smartphone gps apps to record my trips, but I often forgot to start or stop recording. Then I used a bicycle computer, but I didn't like it too, because I had to remove it from the handlebar every time I locked my bike on the street.

The ideal device I am looking for is similar to any bluetooth speed sensor, but can record my speed (or at least total distance) without my phone, has decent battery life, has bluetooth 4.0 connectivity to download recorded data once in a while, and I can leave it on the bike.

I do not need wires, screens, just a small smart sensor, which can record data on its own. Is there anything like that on the market?
I have used cheap bike computers for several years on three different bikes. These are the simplest solution for tracking mileage. I never remove them from the handlebars when I park and none ever got stolen; I don't think they are very attractive to thieves. (If you are worried about theft, note that your fancy Bluetooth-enabled speed sensor might also get stolen...)