rruff wrote:
marcag wrote:
But right now you and I have much bigger sources of error to worry about.I must confess, I really don't know what you are talking about...
It's impossible to get good results if you ignore important variables. Assuming that Crr is only dependent on ambient temperature (rather than tire temperature) can be a 6% error in CdA as I showed earlier. I'm measuring temperature and pressure in real time with CdACrr, so density isn't an issue. And my PM is zeroed before and in the middle of every run (Powertap). The temperature variation on my course is quite small anyway. This would generally be the case when testing. It's sounds like you are just using your TT data as a CdA test? That's obviously going to have greater challenges and error.
I am not sure how/where you showed the 6%.
Here is the thread where Tom A talks about correcting CRR with ambient temp.
https://forum.slowtwitch.com/...%20temp%20q#p3916843
Too bad some of the charts aren't there anymore.
I am curious how your app corrects air density as you move around the course. I suspect it reads the closest weather station ? If so, how often does it refresh and how does it correct as you roll around the course
I do not use my TT exclusively. I use my TT, I do velodrome, I have done Alphamantis velodrome testing, I do small loops using Aerolab,, , I have been to the wind tunnel to confirm numbers....
Nobody is ignoring variables. What I said was some devices do not need air density, therefore eliminating a source of error/noise.
If you are gtting very different numbers from day to day I suspect there is more to it than temp impact on CRR