No-magnet speed sensor

[Abhijit Kshirsagar]

Hello all

I recently bought a new wireless cyclocomputer [1] from Decathlon and
was surprised to find that the wheel rotation sensor is totally
magnet-free. Instead, the sensor is a single unit that gets wrapped
around the body of the front hub that possibly has either a MEMS based
or old-school mechanical orientation sensor in it. The sensor and the
head unit are both powered by a single CR2032 each.

So - no question of aligning magnets on spokes. But getting this on
and off is a bit of a pain - I'll find out how bad it is when the
battery runs out.

(photos here: https://imgur.com/a/Kb6bfHi)


~Abhijit

[1] https://www.decathlon.in/p/8382194/bike-computers/500-wireless-cyclometer-yellow

[Hari Krishna]

My power meter also measures cadence. Goes by the same logic.

--

---
You received this message because you are subscribed to the Google Groups "IISc Bikers Network" group.
To unsubscribe from this group and stop receiving emails from it, send an email to iiscbikersnetw...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/iiscbikersnetwork/CACNnPRn%3D6mbQ4urRv1%2BS12evaGiE36pWzegkPLs0KHxv33FbsA%40mail.gmail.com.

[Sreepathi Pai]

Yes this is now a thing, made popular by Wahoo and others I think.

My sensors, both cadence and speed use this principle.

The big problem is response time. I run a standard wired speed sensor
on my front hub and it picks up speed changes faster than the hub
versions. Might be related to the radius.

> To view this discussion on the web visit https://groups.google.com/d/msgid/iiscbikersnetwork/CAMwHhvr%3DjoMW1FT-ZjeCWOnwEUPPjyVH-ckREUj4fHjm6QNiCg%40mail.gmail.com.



--
Sreepathi Pai

[Abhijit Kshirsagar]

> Yes this is now a thing, made popular by Wahoo and others I think.

Cool - this is the first time Ive seen this

> My sensors, both cadence and speed use this principle.

I thought you had the Sigma wired computer.

> The big problem is response time. I run a standard wired speed sensor
> on my front hub and it picks up speed changes faster than the hub

Interesting observation. There's obviously some delay due to the
sensor and receiver "waking up" and handshaking...

> versions. Might be related to the radius.

Radius of the hub or wheel? Should be immaterial I think - no matter
what the radius.
The sensitivity should be about 90 deg if there's a single axis
accelerometer in it.

If anyone has a broken one, please donate for science :)

Abhijit