RChung wrote:
Pierre,
Have you noticed whether you get different airspeed readings if the Notio is mounted elsewhere (like, at the end of the base bar vs. under one of the aerobar extensions)?
Robert,
I think Marc probably gives a much more informed answer to the one I'll give you... but here is what I can tell you :
- haven't tried moving the sensor around on same day with similar conditions to see if wind speed would come back different relative to sensor position... I'm always trying to measure differences between setups so the CdA reported is what it is and I'm not expecting an absolute value, as long as the differences are measured properly.
- one thing I've never understood with Notio and have told the Notio team is this "Once the calibration factor has been found, there is no need to change it unless the Notio or cockpit configuration changes (i.e. stack, angle, etc.).", most people are going to want to try to move their cockpit during an aero testing session, so if you need to change your calibration factor (3km out + 3km back with no car is a pain in the ass of a calibration if you ask me...) when you change your cockpit setup it becomes absolutely impossible to test changes in that area with the Notio IMHO.
- so by placing it on side of basebar I think you can do pretty much anything in the middle without having to worry about the calibration factor needing to be changed.
- BUT, having the sensor on the side gives very suspicious low calibration factor that makes the CdA wrong if you apply the calibration factor it gives you. Factory calibration factor on a Notio is 1.39 , when I have the sensor in the middle I'm always very close to factory calibration factor (between 1.38 and 1.395) to the point that I live it at 1.39 since the repeatability at different values is not good enough that it justifies changing it. With the Notio on the left of base bar, I'm getting calibration factor between 1.32 and 1.35 (which is a WIDE range) but also very low, you would think since it is a different position it would make sense to trust that a change in calibration factor is needed BUT this change will actually give me a very CdA (increase of around 0.02), so it seems the Notio to the side ask you for a lower calibration factor that you should NOT apply...
Don't know if this is all clear... and in case you could not feel it from my tone, I'm not the biggest fan of the Notio (actually for that reason but also a couple of other even more important ones). It's always exciting to install such a tool on the bike and since you are going to get more precise in your measurements but my findings both on indoor velodrome and outside it that I'm probably less precise with Notio that other measurement methods with a much longer post analysis time to get result... so feel like a LOOSE-LOOSE situation to me which I'm pretty sad about :-( .