Hi,
The light/reflection method is sensitive to dirt.
That's why they use the clip on magnets.
Calculation:
For RPM you don't need to know the radius.
But for speed you need to know the radius.
Klaus
I can see the magnetic version (magnetometer?)
I'm curious why rpm doesn't need radius?
Well... although the tip velocity will vary by diameter, the whole spoke is still rotating at the same RPM?
What would matter then, the size of the surface area? I mean how would you even calibrate it in the first place?
Unless it's just counting break, working, break... which I would think is influenced by the size of the breaker (width).
Interesting catch
Also although I might not have specified, this is for indoor application, riding a bicycle while wearing a VR headset, the rpms/turning inputs are fed into the app to modify the experience, speed, playback, etc...
That's the thought anyway
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Also consider detecting the tire valve. It's a larger diameter than spokes, therefore its silhouette is wider. You would need to find a way to distinguish it from spokes. Your detector needs to be mounted on the opposite side of the tire from the led.
yeah could have a U - design where the U goes over the tire provided a sufficient distance maybe a screw that you twist like a vice to vary the distance between the transmitter/receiver and the reflector panel.
C_mitra, thanks for the tip regarding the reflective tape.
Thanks for the link hobbyckts.