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#11
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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
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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).Â* 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.Â* 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.Â* 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.Â* 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
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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
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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
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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).Â* 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.Â* 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.Â* 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.Â* 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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