Jeff Liebermann wrote:
On Sun, 25 Nov 2018 23:20:50 -0800, Jeff Liebermann
wrote:

On Mon, 26 Nov 2018 06:09:48 +0000 (UTC), Ralph Barone
wrote:
I'm hoping that this turns out to be real and usable hardware. The price
and the ability to use any type of pedal in exchange for an extra 32 mm of
Q factor seems to be a reasonable trade off.
https://www.iqsquare.com

$180 for one sensor. Ouch.
https://www.indiegogo.com/projects/cycling-power-meter-at-a-breakthrough-price#/
Funded to 10 times the original funding price. Very impressive.

I can't see much in the way of numbers, so I'll have to guess(tm) what
might go wrong.
1. There are no visible seals. In order to measure pressure
(actually torque) with a wire strain guage, there has to be some
rotation between the input and output threaded inserts. The movement
will be small and will need to be sealed.
2. The sensor is a nanotech wire strain guage which simply works by
bending a thin wire.
https://www.technologyreview.com/s/407439/a-nano-pressure-sensor/
https://www.sido-event.com/public/exposants_files/Nanolike_nanogauges.pdf
There are similar wires made from other materials. To obtain usable
output voltages and high gain factors, these are usually high
impedance devices, which make them sensitive to condensation, PCB
leakage, RFI, EMI, etc. Hopefully, these factors will not be a
problem.
3. I don't see any calibration adjustments. Hopefully, this would be
done in software. If not, this might be a throw-away device.
4. Hmmm... looks like 4 wires in the strain gauge, which takes care
of measuring strain on any axis and differentially removing wire
temperature from the equation. Nice.
https://c1.iggcdn.com/indiegogo-media-prod-cld/image/upload/c_limit,f_auto,w_620/v1523883251/dvuysosibnhpgupa8jqd.jpg

Oh-oh. Looks like there has been a fundamental change made along the
way:
https://www.indiegogo.com/projects/cycling-power-meter-at-a-breakthrough-price#/
Scroll down to "Full Specifications" and note that the "Sensor" is a:
Full bridge thin film strain gauge, molecularly bonded
to the surface of the titanium adapter.
Nano wires would have given more output, but I suspect may have had
"bonding", cost, and environmental sensitivity problems. So, a step
backwards to a more conventional thin film strain gauge, which can be
purchased off the shelf and is a better characterized device. The
"molecularly bonded" part sounds more like "glued" to me. It will be
interesting to see how many pedal strokes (revolutions) this thing can
handle before the thin film strain gauge delaminates itself from the
titanium sleeve.

Ummm... 1% power accuracy. 1% of what? 1% of measurement? 1% of
full scale? Since full scale is 2600 watts, is it only accurate to
+/- 26 watts?

There are still a number of unanswered questions, which is why they don't
have my money yet. Like all new product development projects, they're
behind schedule, and they haven't provided enough real world test data to
keep all the backers happy. However, the price point (160 Euro each, 260
Euro for a pair) is lower than any other direct measuring power meter out
there.