I enjoy cycling regularly whether it is to get around town, commuting, for leisure or for fitness. Occasionally I think about combining this with a microcontroller such as the Arduino Nano or a Raspberry PI.
The obvious place to go with this theme is a bike 'speedometer' and GPS. I'm sure this would be a fun exercise and opens up lots of possibilities for taking the concept beyond what is provided commercially.
A magnetic hall effect sensor can be bought for under a pound and would allow us to read wheel rotation speed and crank revolutions - so cadence.
A relatively cheap GPS is available which can be connected over the serial lines - RX/TX. In this case I'd try the Neo 6M - which I have seen for £7-9.
A small 2-3" OLED display or 16x2 Hitachi LCD could be used for up-front information on the cockpit. Or LEDs and vibration motors could provide an alternative form of feedback.
Here is my version of a speedo with audio feedback on every rotation of the wheel and a pulsing LED.
- LED strip lighting
I suspect this may violate some regional or local bi-laws or restrictions so best look into this idea before going for a test ride.
Adhesive and waterproof LED strip-lighting can be bought relatively cheaply from the far east. It could be wrapped around the top tube, down tube, rear stays or even the seat tube - maybe all of them at once. The drawback is that the cheaper LED strips run at 12V and can draw a fair amount of current meaning you may need to carry a high current battery on your bike.
- Sonar for safety
A HC-SR04 ultrasonic sensor can be bought for £1-2 and will give a measurement and reading between around 2cm and 250cm. The concept would be to mount the sensor either side facing or rear facing.
A rear facing range-finder provides a warning about cars coming up behind you about to overtake or riding too close. The low tech alternative would be a wing mirror.
I attached this version to my bike and went for a test ride - a van approached behind me and followed me for 200ft but the sensor did not go off. This made me think that the 2.5m range is not enough especially if on a country lane or noisy road.
The side facing version is not going to provide the same advance warning of an overtake but could be useful in conjunction with a camera for capturing dangerous manoeuvres.
Do you have any other ideas? Let me know in the comments.