Bike POV Displays RPM

This bike mounted POV is unique, there have been quite a few floating around recently but I have never seen one that calculated and displayed the RPM of the device. Based on wheel diameter the current speed would also be easy to calculate and display.
Original article (link within text is converted to English)

Here are some links to some other Bike POVs:
Link 1, Link 2, Link 3, Link 4, Link 5, Link 6

“In an article of Make Magazine volume 1 Glowstick heading has Go-Go, it was a question of a series of leds temporarily posting each vertical line of a small image. When one quickly moves this series of leds in space (with its hand), the image is recreated and seems to float in the vacuum.”