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Power Meter



 
 
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  #1  
Old November 26th 18, 01:50 AM posted to rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 459
Default Power Meter

I was writing up a description of a power meter that would use air pressure to calculate applied power.

If you know;

1. Frontal area
2. Aerodynamic drag factor
3. Grade
4. Barometric pressure
5. Grade
6. Total weight
7. Speed

You could calculate the amount of power you are applying to drive the bike forward. This would be a little off since there are drivetrain losses and losses from things like rocking the bike back and forth and rolling resistance. But these are relatively minor and you could probably calculate a correction factor since these are all linear corrections.

In any event while looking things up I discovered that someone beat me to the punch.

There is the $149 WattZit and the "Starting At" $199 PowerPod.

Both of these are using this idea.

The WattZit is a start-up and the stuff is still a little crude but he seems to be moving in the right direction quite rapidly.

The PowerPod is a lot more highly developed but you would have to buy in pretty deeply to get all the real bells and whistles.

What I have been doing to this point is to use an altimeter/Speedo that gives average climb and speed then using Steve Gribbles power calculator to estimate power I'm putting out.

The numbers I've been getting from this method have been cross checked with papers on actual power outputs of different classes of racers and I have been a little on the low side of my supposed category. This matches with the way that I feel my performance is.

I have two or three hard rides a week in good weather and I tend to be the last one up every hill. Though now that I'm using Propel in my water bottle I'm not exhausted after every ride.

Three years ago I could give some really hard bursts of performance but that slowed up over the last three years until I'm down to slow and steady. I got a copy of Joe Friel's "Fast Over 50" but it appears to me that he lives on flat terrain and his training methods aren't easily converted to hilly terrain. But doing the best conversions I can I've seen some improvement if not what I'd like to think I remember.

So since the WattZit is cheap I got one to try.

His instructions on how to use it are pretty bad but perhaps that's the result of my concussion. They DO give you the information you need if you have to study it a bit. I finally discovered that the empty box of SmartLink included was from the component that had already been installed in the WattZit.

Then the App just would not install. I tried a dozen times on Friday and nothing would work. I got up Saturday and tried again and it downloaded from the email he had sent me and installed with no problem. I couldn't have done it wrong since all you had to do was click on the App and then hit "INSTALL" when it took over the whole screen.

In the meantime he upgraded the APP from 1.1 to 2.0. The bike unit measures speed by a wheel magnet but on the updated APP you can use GPS instead. I will try both but my suspicion is that the GPS is slightly better.

WattZit claims a +/-5% and PowerPod a +/-2%. My guess is that this difference is in the initial set-up procedure. The WattZit appears to make an approximation of Frontal Area and estimates aerodynamic drag with handlebar type.. PowerPod uses the same hanglebar type but has you do some "set-up" runs that give a better estimate of frontal area.

As I'm trying this WattZit I'll keep you informed of what I think of it.
Ads
  #2  
Old November 26th 18, 02:59 AM posted to rec.bicycles.tech
Claus Amann
external usenet poster
 
Posts: 12
Default Power Meter

If you know;

1. Frontal area
2. Aerodynamic drag factor


How do you "know" these two?
How do you determine when they are changing
due to a change of your position?

3. Grade
4. Barometric pressure
5. Grade


Are 3 and 5 different?

Maybe 5 should be "wind"? (direction/strength?)
That's what the "PowerPod" measures, right?

You could calculate the amount of power you are applying to drive the bike forward. This would be a little off


"a little"? that depends on how well you "know" all those input
parameters.
Moreover, "rolling resistance" could be a bigger factor than
"Barometric pressure" (time trial tyres vs "studded" tyres?)


--
Note: please read the netiquette before posting. I will almost never
reply to top-postings which include a full copy of the previous
article(s) at the end because it's annoying, shows that the poster
is too lazy to trim his article, and it's wasting the time of all readers.
  #3  
Old November 26th 18, 07:09 AM posted to rec.bicycles.tech
Ralph Barone[_4_]
external usenet poster
 
Posts: 196
Default Power Meter

wrote:
I was writing up a description of a power meter that would use air
pressure to calculate applied power.

If you know;

1. Frontal area
2. Aerodynamic drag factor
3. Grade
4. Barometric pressure
5. Grade
6. Total weight
7. Speed

You could calculate the amount of power you are applying to drive the
bike forward. This would be a little off since there are drivetrain
losses and losses from things like rocking the bike back and forth and
rolling resistance. But these are relatively minor and you could probably
calculate a correction factor since these are all linear corrections.

In any event while looking things up I discovered that someone beat me to the punch.

There is the $149 WattZit and the "Starting At" $199 PowerPod.

Both of these are using this idea.

The WattZit is a start-up and the stuff is still a little crude but he
seems to be moving in the right direction quite rapidly.

The PowerPod is a lot more highly developed but you would have to buy in
pretty deeply to get all the real bells and whistles.

What I have been doing to this point is to use an altimeter/Speedo that
gives average climb and speed then using Steve Gribbles power calculator
to estimate power I'm putting out.

The numbers I've been getting from this method have been cross checked
with papers on actual power outputs of different classes of racers and I
have been a little on the low side of my supposed category. This matches
with the way that I feel my performance is.

I have two or three hard rides a week in good weather and I tend to be
the last one up every hill. Though now that I'm using Propel in my water
bottle I'm not exhausted after every ride.

Three years ago I could give some really hard bursts of performance but
that slowed up over the last three years until I'm down to slow and
steady. I got a copy of Joe Friel's "Fast Over 50" but it appears to me
that he lives on flat terrain and his training methods aren't easily
converted to hilly terrain. But doing the best conversions I can I've
seen some improvement if not what I'd like to think I remember.

So since the WattZit is cheap I got one to try.

His instructions on how to use it are pretty bad but perhaps that's the
result of my concussion. They DO give you the information you need if you
have to study it a bit. I finally discovered that the empty box of
SmartLink included was from the component that had already been installed in the WattZit.

Then the App just would not install. I tried a dozen times on Friday and
nothing would work. I got up Saturday and tried again and it downloaded
from the email he had sent me and installed with no problem. I couldn't
have done it wrong since all you had to do was click on the App and then
hit "INSTALL" when it took over the whole screen.

In the meantime he upgraded the APP from 1.1 to 2.0. The bike unit
measures speed by a wheel magnet but on the updated APP you can use GPS
instead. I will try both but my suspicion is that the GPS is slightly better.

WattZit claims a +/-5% and PowerPod a +/-2%. My guess is that this
difference is in the initial set-up procedure. The WattZit appears to
make an approximation of Frontal Area and estimates aerodynamic drag with
handlebar type. PowerPod uses the same hanglebar type but has you do some
"set-up" runs that give a better estimate of frontal area.

As I'm trying this WattZit I'll keep you informed of what I think of it.


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

  #4  
Old November 26th 18, 08:20 AM posted to rec.bicycles.tech
Jeff Liebermann
external usenet poster
 
Posts: 2,919
Default Power Meter

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

--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
  #5  
Old November 26th 18, 08:48 AM posted to rec.bicycles.tech
Jeff Liebermann
external usenet poster
 
Posts: 2,919
Default Power Meter

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?



--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
  #6  
Old November 26th 18, 02:49 PM posted to rec.bicycles.tech
Ralph Barone[_4_]
external usenet poster
 
Posts: 196
Default Power Meter

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.

  #7  
Old November 26th 18, 04:09 PM posted to rec.bicycles.tech
JBeattie
external usenet poster
 
Posts: 3,485
Default Power Meter

On Monday, November 26, 2018 at 5:49:13 AM UTC-8, Ralph Barone wrote:
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.


You wonder how the company could stay in business with a low dollar, low volume product -- in a market that is not that price sensitive and that is packed with competitors who have reliable products, customer service departments and other revenue streams.

-- Jay Beattie.

  #8  
Old November 26th 18, 04:27 PM posted to rec.bicycles.tech
Ralph Barone[_4_]
external usenet poster
 
Posts: 196
Default Power Meter

jbeattie wrote:
On Monday, November 26, 2018 at 5:49:13 AM UTC-8, Ralph Barone wrote:
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.


You wonder how the company could stay in business with a low dollar, low
volume product -- in a market that is not that price sensitive and that
is packed with competitors who have reliable products, customer service
departments and other revenue streams.

-- Jay Beattie.


As a price sensitive customer (although at my fitness level I need a power
meter about as much as I need gold plated shifters) I do hope that they
succeed.

  #9  
Old November 26th 18, 04:46 PM posted to rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 459
Default Power Meter

On Sunday, November 25, 2018 at 5:59:56 PM UTC-8, Claus Aßmann wrote:
If you know;


1. Frontal area
2. Aerodynamic drag factor


How do you "know" these two?
How do you determine when they are changing
due to a change of your position?


This is a function of firmware engineering and is somewhat classified information for my part. PowerPod setup procedures pretty much makes it obvious if you're an engineer.

3. Grade
4. Barometric pressure
5. Grade


Are 3 and 5 different?


Perhaps you should correct my spelling as well.

Maybe 5 should be "wind"? (direction/strength?)
That's what the "PowerPod" measures, right?


Can you suggest how you can tell the difference between wind and speed merely by the wind speed? You could use GPS or wheel magnet speed but the wind in the face is the actual power load on the rider.

You could calculate the amount of power you are applying to drive the bike forward. This would be a little off


"a little"? that depends on how well you "know" all those input
parameters.
Moreover, "rolling resistance" could be a bigger factor than
"Barometric pressure" (time trial tyres vs "studded" tyres?)


Your riding position changes remarkably little if you are riding hard. This is verified by the other popular methods of power measurement. Perhaps on downhills you sit up to use your increased drag to limit the speed but this slowing adds to your course time and subtracts from your overall power.

Or perhaps you would like to see how much power you're generating for your cruiser?

  #10  
Old November 26th 18, 05:51 PM posted to rec.bicycles.tech
JBeattie
external usenet poster
 
Posts: 3,485
Default Power Meter

On Monday, November 26, 2018 at 7:27:25 AM UTC-8, Ralph Barone wrote:
jbeattie wrote:
On Monday, November 26, 2018 at 5:49:13 AM UTC-8, Ralph Barone wrote:
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.


You wonder how the company could stay in business with a low dollar, low
volume product -- in a market that is not that price sensitive and that
is packed with competitors who have reliable products, customer service
departments and other revenue streams.

-- Jay Beattie.


As a price sensitive customer (although at my fitness level I need a power
meter about as much as I need gold plated shifters) I do hope that they
succeed.


Most people who are power-junkies can easily afford the $250 spread between an IQ2 and a Stages Gen 3. And the increased cost gets you reliability and generous customer service -- and not a Kickstarter company that could go belly up like some of the other entrants, e.g. https://www.dcrainmaker.com/2018/11/...quisition.html -- the prior greatest low cost pedal-based power meter, now defunct.

I'm all for low cost, too, but being an early adopter of the low-cost option is a crap shoot at best. I've done it with other products and regretted it. A power meter, at least, just stops working -- unlike some other products I've owned that made my life worse like broken super-light pedals, leaking first generation Goretex tents, broken first generation Weyless two-bolt seat posts, etc. In the old days, these things lurked at the back of Bicycling Magazine. Now they're on Kickstarter and other funding sites.

-- Jay Beattie.



 




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