I really appreciate all the positive help that I have received from simply reading other issues that people have dealt with. This is the first time that I was not able to find help for a problem that I have by simply searching the forum so I hope it is not too difficult of a question and someone out there can help me.
Recently my ibike Pro Gen III has been over estimating wind speed. The result is higher power numbers then I expect (maybe I shouldn't complain about this)! I'll do a ride that is an out and back and when I upload the ride to my computer I'll find that my average wind speed is usually around 8-9 mph (headwind). It of course should be close to zero being that I go out and back. I can correct this using the software, however I would like to be able to read my ibike pro while I am out on a ride and know that it is giving me correct information.
I do a offset calibration before every ride and it always reads close to "0" when I do it. Don't know if there is any other information required but feel free to chime in with ideas.
tim
Average Wind speed error
Re: Average Wind speed error
Your wind scaling number is off.
If you send me the ride file that you did from a solo ride, I'll be able to determine a new wind scaling number for you and send you back an updated profile.
You can mail me the file at boyd (at) totalcyclist dot com.
If you send me the ride file that you did from a solo ride, I'll be able to determine a new wind scaling number for you and send you back an updated profile.
You can mail me the file at boyd (at) totalcyclist dot com.
Boyd Johnson
http://www.boydcycling.com - high performance carbon wheels and accessories
http://www.boydcycling.com - high performance carbon wheels and accessories
Re: Average Wind speed error
thanks, I'll send you one next time I go out. All the files I have saved now have been "corrected" so they wouldn't be of much use. Thanks for your quick reply!
Re: Average Wind speed error
Emailed you the file, let me know if you didn't receive and I can resend if necessary.
Re: Average Wind speed error
You can check this at any time and adjust the wind scaling yourself. The best venue would be a quiet residential area with little traffic. Even better would be a spot where you can ride in the same part of the road for both directions... this will ensure that obstructions are not causing the wind to look different on one side of the street vs the other. Light winds will give the best results... at any rate you will want to avoid spending a significant amount of time *ever* going slower than a tailwind. If you have a tailwind, slow down quickly at the turnaround to minimize this.
This actually works the best if the out-back course is fairly short and you do several laps... this will help account for any shift in the wind that may occur.
a) Make sure your wind offset is zeroed.
b) Do a Trip Reset.
c) Ride back and forth over the course at a normal riding speed... the more laps the better.
d) End at your starting point and do another Trip Reset.
You can create as many of these files as you like to check repeatability.
When you get home, go into iBike3 and check "Analyze Wind" for this file. Ideally you want to see zero, but a few 1/10ths of a mph plus or minus isn't bad either. The adjustment to wind scaling that would be applicable is (Vb/Vw)^2. For instance if your avg bike speed is 19.0 and your avg wind speed is 20.0, the correction to your wind scaling would be (19/20)^2= .90. Multiply this by your old wind scaling to get the new value.
This actually works the best if the out-back course is fairly short and you do several laps... this will help account for any shift in the wind that may occur.
a) Make sure your wind offset is zeroed.
b) Do a Trip Reset.
c) Ride back and forth over the course at a normal riding speed... the more laps the better.
d) End at your starting point and do another Trip Reset.
You can create as many of these files as you like to check repeatability.
When you get home, go into iBike3 and check "Analyze Wind" for this file. Ideally you want to see zero, but a few 1/10ths of a mph plus or minus isn't bad either. The adjustment to wind scaling that would be applicable is (Vb/Vw)^2. For instance if your avg bike speed is 19.0 and your avg wind speed is 20.0, the correction to your wind scaling would be (19/20)^2= .90. Multiply this by your old wind scaling to get the new value.
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lorduintah
- Posts: 670
- Joined: Fri Jan 11, 2008 9:37 am
- Location: Plymouth, MN
Re: Average Wind speed error
I found that you can also take advantage of the LAP feature. This replaces the Trip Reset option of running this check.
Set up the iBike like mentioned above, zero calibration for the wind offset.
Then hit the left arrow button long enough to have LAP flash.
Do 3-5 circuits of the back and forth over the short course (I used 0.4 miles in one direction), then mark another LAP. (see "C" above as this is a change)
Do this 3 or more times and you can calculate an average correction by lap and for the total mileage of all the laps.
This might show a little variation, but, I think that is also more information that comes in useful. These coefficients are not absolute numbers - there are valid ranges during rides.
Tom
Set up the iBike like mentioned above, zero calibration for the wind offset.
Then hit the left arrow button long enough to have LAP flash.
Do 3-5 circuits of the back and forth over the short course (I used 0.4 miles in one direction), then mark another LAP. (see "C" above as this is a change)
Do this 3 or more times and you can calculate an average correction by lap and for the total mileage of all the laps.
This might show a little variation, but, I think that is also more information that comes in useful. These coefficients are not absolute numbers - there are valid ranges during rides.
Tom