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Fastest bike?



 
 
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  #11  
Old July 5th 18, 02:14 AM posted to rec.bicycles.tech
James[_8_]
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Posts: 5,739
Default Fastest bike?

On 05/07/18 10:40, jbeattie wrote:
On Wednesday, July 4, 2018 at 3:32:42 PM UTC-7, James wrote:
On 05/07/18 02:48, jbeattie wrote:

You can buy Stages two-sided, if you're into accuracy, which may be an issue if you're switching between bikes or really concerned about accurate calorie burn numbers-- or are in some sort of competition with other riders (who may or may not be posting accurate power data). Otherwise, I think consistency is more important than accuracy. Spikes can be filtered with data ceilings, etc., but the spike my son had -- which was actually 1,732 watts is within the one second power output of Chris Hoy. It was recorded by having the right crank forward on a bumpy descent and not by massive quads, but the meter is just recording numbers accurately. It's not going to filter that out. Maybe he is Chris Hoy! You can download the data and apply filters later.


Is the crank position (cadence) sensor on the left crank and left chain
stay?

I wonder if the unit "thought" the cranks were rotating because the
rotation sensor recorded some jitter at the same time the load cell did?

To eliminate this by design, a better crank position sensor would help.
An encoder ring on the crank and sensor on the BB, for example. Then
you don't need to try to "fix" the data afterwards, which I always see
as a giant fudge for poor engineering design.

--
JS


No sensors. It's bluetooth and ant+ connectivity. https://stagescycling.com/us/technology/


Rotational power is determined from Torque and rotational speed. The
stages device may use an accelerometer _sensor_ to sense gravity, and
uses that to determine the crank rotational speed. The bumpy road
likely confused the rotational speed sensing logic. Again, a better
engineered crank position sensor would fix that.

--
JS
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  #12  
Old July 5th 18, 01:58 PM posted to rec.bicycles.tech
SMS
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Posts: 8,281
Default Fastest bike?

On 7/4/2018 3:28 PM, James wrote:
On 05/07/18 02:48, jbeattie wrote:

You can buy Stages two-sided, if you're into accuracy, which may be an
issue if you're switching between bikes or really concerned about
accurate calorie burn numbers-- or are in some sort of competition
with other riders (who may or may not be posting accurate power
data).* Otherwise, I think consistency is more important than
accuracy. Spikes can be filtered with data ceilings, etc., but the
spike my son had -- which was actually 1,732 watts is within the one
second power output of Chris Hoy.* It was recorded by having the right
crank forward on a bumpy descent and not by massive quads, but the
meter is just recording numbers accurately. It's not going to filter
that out.* Maybe he is Chris Hoy! You can download the data and apply
filters later.


Is the crank position (cadence) sensor on the left crank and left chain
stay?

I wonder if the unit "thought" the cranks were rotating because the
rotation sensor recorded some jitter at the same time the load cell did?

To eliminate this by design, a better crank position sensor would help.
An encoder ring on the crank and sensor on the BB, for example.* Then
you don't need to try to "fix" the data afterwards, which I always see
as a giant fudge for poor engineering design.


Do any of the power meters have a position sensor?

There was a design of a power meter that had the strain gauge in the
bottom bracket as part of the spindle. That would have seemed to be a
better option, but not as easy to retrofit as a crankarm design, and a
pain to change the batteries.

  #13  
Old July 5th 18, 03:02 PM posted to rec.bicycles.tech
JBeattie
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Posts: 3,216
Default Fastest bike?

On Wednesday, July 4, 2018 at 6:15:09 PM UTC-7, James wrote:
On 05/07/18 10:40, jbeattie wrote:
On Wednesday, July 4, 2018 at 3:32:42 PM UTC-7, James wrote:
On 05/07/18 02:48, jbeattie wrote:

You can buy Stages two-sided, if you're into accuracy, which may be an issue if you're switching between bikes or really concerned about accurate calorie burn numbers-- or are in some sort of competition with other riders (who may or may not be posting accurate power data). Otherwise, I think consistency is more important than accuracy. Spikes can be filtered with data ceilings, etc., but the spike my son had -- which was actually 1,732 watts is within the one second power output of Chris Hoy. It was recorded by having the right crank forward on a bumpy descent and not by massive quads, but the meter is just recording numbers accurately. It's not going to filter that out. Maybe he is Chris Hoy! You can download the data and apply filters later.


Is the crank position (cadence) sensor on the left crank and left chain
stay?

I wonder if the unit "thought" the cranks were rotating because the
rotation sensor recorded some jitter at the same time the load cell did?

To eliminate this by design, a better crank position sensor would help..
An encoder ring on the crank and sensor on the BB, for example. Then
you don't need to try to "fix" the data afterwards, which I always see
as a giant fudge for poor engineering design.

--
JS


No sensors. It's bluetooth and ant+ connectivity. https://stagescycling.com/us/technology/


Rotational power is determined from Torque and rotational speed. The
stages device may use an accelerometer _sensor_ to sense gravity, and
uses that to determine the crank rotational speed. The bumpy road
likely confused the rotational speed sensing logic. Again, a better
engineered crank position sensor would fix that.


I thought by sensor you meant a pick-up on the chain stay. Yes, it has an accelerometer and a strain gauge.

-- Jay Beattie.
  #14  
Old July 5th 18, 04:48 PM posted to rec.bicycles.tech
AMuzi
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Posts: 9,554
Default Fastest bike?

On 7/4/2018 5:28 PM, James wrote:
On 05/07/18 02:48, jbeattie wrote:

You can buy Stages two-sided, if you're into accuracy,
which may be an issue if you're switching between bikes or
really concerned about accurate calorie burn numbers-- or
are in some sort of competition with other riders (who may
or may not be posting accurate power data). Otherwise, I
think consistency is more important than accuracy. Spikes
can be filtered with data ceilings, etc., but the spike my
son had -- which was actually 1,732 watts is within the
one second power output of Chris Hoy. It was recorded by
having the right crank forward on a bumpy descent and not
by massive quads, but the meter is just recording numbers
accurately. It's not going to filter that out. Maybe he
is Chris Hoy! You can download the data and apply filters
later.


Is the crank position (cadence) sensor on the left crank and
left chain stay?

I wonder if the unit "thought" the cranks were rotating
because the rotation sensor recorded some jitter at the same
time the load cell did?

To eliminate this by design, a better crank position sensor
would help. An encoder ring on the crank and sensor on the
BB, for example. Then you don't need to try to "fix" the
data afterwards, which I always see as a giant fudge for
poor engineering design.



Those are usually strain gauges inside or on the arm, not a
magnet/sensor interface to a chainstay sensor like a cadence
counter.

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971


  #15  
Old July 6th 18, 01:52 AM posted to rec.bicycles.tech
James[_8_]
external usenet poster
 
Posts: 5,739
Default Fastest bike?

On 06/07/18 01:48, AMuzi wrote:
On 7/4/2018 5:28 PM, James wrote:
On 05/07/18 02:48, jbeattie wrote:

You can buy Stages two-sided, if you're into accuracy,
which may be an issue if you're switching between bikes or
really concerned about accurate calorie burn numbers-- or
are in some sort of competition with other riders (who may
or may not be posting accurate power data).* Otherwise, I
think consistency is more important than accuracy. Spikes
can be filtered with data ceilings, etc., but the spike my
son had -- which was actually 1,732 watts is within the
one second power output of Chris Hoy.* It was recorded by
having the right crank forward on a bumpy descent and not
by massive quads, but the meter is just recording numbers
accurately. It's not going to filter that out.* Maybe he
is Chris Hoy! You can download the data and apply filters
later.


Is the crank position (cadence) sensor on the left crank and
left chain stay?

I wonder if the unit "thought" the cranks were rotating
because the rotation sensor recorded some jitter at the same
time the load cell did?

To eliminate this by design, a better crank position sensor
would help. An encoder ring on the crank and sensor on the
BB, for example.* Then you don't need to try to "fix" the
data afterwards, which I always see as a giant fudge for
poor engineering design.



Those are usually strain gauges inside or on the arm, not a
magnet/sensor interface to a chainstay sensor like a cadence counter.


The strain gauges are for the torque measurement, but to calculate power
the device needs to know the angular velocity of the crank as well.

The stages unit has an accelerometer for that purpose, as Jay noted, and
obviously that solution isn't fool proof because the data has erroneous
values.

--
JS
 




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