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Wind Scaling Numbers
Posted: Sun Mar 15, 2009 2:24 am
by 82zman
Is a wind scaling value of 2.0 acceptable? I am getting very reasonable numbers with the scaling at 2.0.
Aero: 0.668; Fric: 6.77
CdA: 0.333 m^2
Crr: 0.0043
I did two cal rides and they both had 2.0 for wind scaling. The cal ride was on a bike path with little or no wind, no cars etc. Should have been perfect.
I also did 6 CDs. I did a wind offset in the garage after letting the bike sit out for over an hour.
Re: Wind Scaling Numbers
Posted: Sun Mar 15, 2009 8:04 am
by Velocomp
Wind scaling will make your reported wind speed on the iBike equal to the actual wind speed. It is dependent on many things, including iBike mount location, mount angle, and individual characteristics of your iBike.
2.0 is a very acceptable number and your CdA and Crr numbers, both of which are fine, reflect the quality of your wind scaling factor.
Get out there and ride!
Re: Wind Scaling Numbers
Posted: Tue Mar 17, 2009 12:59 pm
by rruff
82zman wrote:Is a wind scaling value of 2.0 acceptable? I am getting very reasonable numbers with the scaling at 2.0.
You can check this at any time by doing a series of out-back "laps" and looking at the "analyze wind" feature in IB3. If it reads close to zero, then you are good.
Re: Wind Scaling Numbers
Posted: Tue Mar 17, 2009 4:18 pm
by Ratman
rruff wrote:82zman wrote:Is a wind scaling value of 2.0 acceptable? I am getting very reasonable numbers with the scaling at 2.0.
You can check this at any time by doing a series of out-back "laps" and looking at the "analyze wind" feature in IB3. If it reads close to zero, then you are good.
Rruff, I assume that by "it" reads close to zero, you're referring to the "Average Ground Wind" value in the "Analyze Wind" window? Or are you actually referring to the "Wind Offset" value?
Thanks.
Re: Wind Scaling Numbers
Posted: Tue Mar 17, 2009 9:48 pm
by 82zman
It would be Avg ground wind. And for the record I did a new cal ride a few days ago and it was golden. Today I did two 2 mi out/back rides and then analyzed the results. I was off by 1 mph avg. I believe these to be great results since today wind was 20-30 mph and gusty.
Re: Wind Scaling Numbers
Posted: Wed Mar 18, 2009 12:37 pm
by rruff
82zman wrote:It would be Avg ground wind. And for the record I did a new cal ride a few days ago and it was golden. Today I did two 2 mi out/back rides and then analyzed the results. I was off by 1 mph avg. I believe these to be great results since today wind was 20-30 mph and gusty.
That is a good result for a windy day. For best results I like to do this on a fairly short course with multiple laps, no traffic, and also ride on the same part of the road in both directions. You just need to make sure you always go faster than any tailwind.