A few days ago, to escape the strong wind blowing downwards on my favorite climb, I went training on a forest road protected from that wind.
It's a short steep climb, from 667 m to 1298 m. over a distance of 5.95 km.
Due to the steepness I often stood on the pedals ( Also, I didn't change my lowest gear and used 36:25) and had inflated my tubulars at 7 bars.
The first km is smooth asphalt, but the last 5 km are rather bouncy and I was wondering whether I would have gained a handful of seconds by using a lower pressure.
What is your experience on that?
Crr
I then went back to the data I took with my Powertap on that same road in May 2003 or 2004.
Total weight 71.3 kg ( so about 70.7 kg on average during the climb). 5.95 km, 35:08 473 kJ.
There is not much speed variation during the climb. My maximum that day was 14.7 km/h
If I exclude road resistance my energy expenditure should have been 447 kJ.
My tests on other days showed me that my Powertap was accurate at the 1% level. So I will assume it was the same that day. (I disregard the uncertainty on the 10 kJ I estimate I lost to air resistance)
Therefore the rolling resistance on that climb accounted for 473 (+/-5kJ) - 447 kJ = 26 +/- 5 kJ.
Since the rolling resistance loss on the 1st km was ~3kJ, it leaves 26-3 =23 kJ (+/-5 kJ) for the last 5 km.
This yields Crr = 0.0065 (+/- 0.0014) for that rough road.
Analyticcycling assigns a Crr = 0.008 to rough roads.
Anybody has personal data on Crr for rough roads?
PS for wattage historians.
20 years ago I had used that same climb to calibrate my Look Max 1.
Total weight was 72 kg, my time 28:56, but my Look Max 1 only indicated 419 kJ and 241 watts average .
On my 1991 agenda I had noted a correction factor of 1.134 ( it changed every week)
It's a short steep climb, from 667 m to 1298 m. over a distance of 5.95 km.
Due to the steepness I often stood on the pedals ( Also, I didn't change my lowest gear and used 36:25) and had inflated my tubulars at 7 bars.
The first km is smooth asphalt, but the last 5 km are rather bouncy and I was wondering whether I would have gained a handful of seconds by using a lower pressure.
What is your experience on that?
Crr
I then went back to the data I took with my Powertap on that same road in May 2003 or 2004.
Total weight 71.3 kg ( so about 70.7 kg on average during the climb). 5.95 km, 35:08 473 kJ.
There is not much speed variation during the climb. My maximum that day was 14.7 km/h
If I exclude road resistance my energy expenditure should have been 447 kJ.
My tests on other days showed me that my Powertap was accurate at the 1% level. So I will assume it was the same that day. (I disregard the uncertainty on the 10 kJ I estimate I lost to air resistance)
Therefore the rolling resistance on that climb accounted for 473 (+/-5kJ) - 447 kJ = 26 +/- 5 kJ.
Since the rolling resistance loss on the 1st km was ~3kJ, it leaves 26-3 =23 kJ (+/-5 kJ) for the last 5 km.
This yields Crr = 0.0065 (+/- 0.0014) for that rough road.
Analyticcycling assigns a Crr = 0.008 to rough roads.
Anybody has personal data on Crr for rough roads?
PS for wattage historians.
20 years ago I had used that same climb to calibrate my Look Max 1.
Total weight was 72 kg, my time 28:56, but my Look Max 1 only indicated 419 kJ and 241 watts average .
On my 1991 agenda I had noted a correction factor of 1.134 ( it changed every week)
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