Looking for bicycle cadence meter w/ colored LEDs

[system]

Am posting here after unsuccessfully searching for this everywhere. What I am looking for is a cadence indicator which would display speed as a color. The output would consist of an array of LEDs of different rainbow colors. As pedal speed increased, different colored LEDs would light up. This would be a very simple way to know your cadence as you would not even need to really look at it directly.

Basically a tachometer set up like a vertical VU meter.

Any ideas?

Thanks.

[system]

You could count the pedalling cadence with a hall effect sensor or a reed switch. (sensor on frame small magnet on pedal arm). Doing the math and lighting up LED's in different colors should be a simple task.