Crr & CdA (& also gradient) - possible PP/Isaac features?
Posted: Sun May 14, 2017 7:55 pm
Trying to take my mind off of a hill I had a couple of thoughts about "extras" that could possible work - I think
First off (& you can guess where the idea came from) there's a sensitive & carefully calibrated accelerometer in the PP that knows what angle (to the horizontal) the PP is pointing. It's zeroed each ride, so presumably the measured angle after that is the same as the gradient of the hill. Could that be broadcast to the head unit? (You'll see that I have no idea about ANT+/BLE broadcast limitations)
Secondly - this thread about estimating Crr & CdA from downhill coast downs. At the moment both of these parameters are calculated estimates from some pretty basic data (for me, at least). Assuming that elevation & speed are logged then "all we need" is a downhill stretch without pedalling & some air density data for the day. I think that the data could be extracted & processed longhand by using the spreadsheet in that thread. I'll have to go back to the hill & try it.
http://forum.slowtwitch.com/cgi-bin/gfo ... 89#3590389
(I wonder if the PP ability to measure wind speed is an even bigger bonus here, allowing us to account for some breeze at the time of the test)
First off (& you can guess where the idea came from) there's a sensitive & carefully calibrated accelerometer in the PP that knows what angle (to the horizontal) the PP is pointing. It's zeroed each ride, so presumably the measured angle after that is the same as the gradient of the hill. Could that be broadcast to the head unit? (You'll see that I have no idea about ANT+/BLE broadcast limitations)
Secondly - this thread about estimating Crr & CdA from downhill coast downs. At the moment both of these parameters are calculated estimates from some pretty basic data (for me, at least). Assuming that elevation & speed are logged then "all we need" is a downhill stretch without pedalling & some air density data for the day. I think that the data could be extracted & processed longhand by using the spreadsheet in that thread. I'll have to go back to the hill & try it.
http://forum.slowtwitch.com/cgi-bin/gfo ... 89#3590389
(I wonder if the PP ability to measure wind speed is an even bigger bonus here, allowing us to account for some breeze at the time of the test)