I had a second try with the Notio aerometer sensor today.
I really wanted to try and improve on what I thought the problems were with the first test - too much altitude change over the test route, too much traffic, too much crosswind and too long a test route to be able to fit multiple runs in without the weather changing over time.
This time I set off at first light 5.52am on Sunday morning to do a 2.52 mile (roughly 9 minute per run) distance route on the flattest main road I could think of without needing to drive there by car. My hope was that by doing the shorter route I could fit in enough test runs on it before there would be much if any passing traffic. There were maybe 1 or 2 cars per test run so not bad but there was a bit of a crosswind.
Along with the test route I also decided to try and make a big enough equipment change that it should give a noticeable difference in CdA. The aim was to try and prove whether the Notio aerometer sensor would be able to identify differences.
For the first 3 runs I started off wearing a Castelli race fit cycling jersey and Giro Aether non aero helmet holding the grips in a normal upright position. I then did a further 3 runs wearing a Castelli San Remo skinsuit and Specialized Evade 2 aero helmet holding the grips in a normal upright position. I had hoped to do a further 3 runs wearing baggy shorts and t-shirt at the end but 6 runs and changing kit took 1 hour 15 minutes so there was already starting to be too much traffic on the main road to be able to keep doing any testing after about 7am.
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This table shows the summary of the 6 test runs that I did. Unlike my first try I actually got what appear to be some reasonable results!
Wearing the jersey and Giro Aether non aero helmet I had an average time for the 2.52 miles of 8 minutes 55 seconds at an average power of 168 watts, average speed 16.9mph. I had an average CdA of 0.417 over the three runs.
Wearing the skinsuit and Specialized Evade 2 aero helmet I had an average time for the 2.52 miles of 8 minutes 47 seconds at an average power of 168 watts, average speed 17.2mph. I had an average CdA of 0.396 over the three runs.
The skinsuit and Specialized Evade 2 aero helmet kit was 8 seconds faster over the 2.52 miles for the same 168 watt power output, an increase in average speed of 0.3mph and a reduction in CdA of 0.021.
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In order to check if the Notio CdA numbers were close I tried putting the same CdA and power output values into this calculator:
Cycling Physics Calculator
Using the Notio CdA numbers the time saving over 2.5 miles (4km) per the calculator was 7 seconds whilst the actual time saving per my test rides was 8 seconds. :eekster:
I was really pleased with that as it shows that given the right test conditions the Notio aerometer does work, certainly for large changes.
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This graph shows the CdA during the third jersey + Giro Aether helmet test run. This was on a flat main road out and back with a u-turn that I had to brake and slow down at the mid point.
Overall the CdA was a lot more stable and consistent on this route for both the out and back portions. It wasn't perfect though. At the start of each test run is that same rapid rise curve from a very low CdA and at the turn point, where I had to brake and slow down, there's a minute afterwards where the CdA jumps to 0.519 which appears to be related to the turn (with a 60 second rolling average the CdA change is delayed) before settling down again for the return trip.
With a better testing route again (even flatter, no wind, no traffic and a turn that doesn't need slowing down for) I think the results could be made better than the ones here.
