Well so far my unit has been working great. I have one problem and that is the wind offset in the analyze wind screen. I am using 2 bikes with 2 profiles for my XC mtb racing. The one bike I thought would be off which is my xc race bike always seems to have a zero avg or very close to it (except with a number plate on, which is a whole other issue). My road mtb is always off (for instance todays ride was 2.6 in the avg box). To adjust it to zero I have to change wind offset to 6.7. Do I need to do another cal ride to get the wind scaling right or is there a tweak that can be done to fix this? Any help would be greatly appreciated.
Clint
Attached is the profile I used and the ride I did today to set my CP.2 and CP1 values.
Wind offset
Re: Wind offset
Again:
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.
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.
Re: Wind offset
I am not sure I understand the formula but I will figure it out. On another note since I have put out my latest profile along with a ride file if someone could look at it and see if it looks ok I would appreciate it. I got some high numbers doing my CP test last night, then again maybe they are just fine??
Re: Wind offset
Here is the same ride with an adjusted profile embedded. Save this file and then go to profiles->edit profiles->extract from ride file. You will then have this profile that you can send to your iBike and that will take care of the wind issues.
One thing you may want to look at is your speed. . .it seems to be jumping all over the place. If that's the case, that could account for a difference in wind speed vs. wheel speed and that would be the fix, instead of a new profile.
One thing you may want to look at is your speed. . .it seems to be jumping all over the place. If that's the case, that could account for a difference in wind speed vs. wheel speed and that would be the fix, instead of a new profile.
- Attachments
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- iBike_10_07_2009_1621_16_Miles.csv
- (1.29 MiB) Downloaded 357 times
Boyd Johnson
http://www.boydcycling.com - high performance carbon wheels and accessories
http://www.boydcycling.com - high performance carbon wheels and accessories
Re: Wind offset
Thank you coachboyd, I will try it out tonight. The profile I was using is the one you had me modify and it seemed to be very close except for that and the 100-200 watts when coasting downhill. I changed my aero number to get those watts close to zero when coasting downhill (in the coast screen)at around 27-30 mph. Now all I have is the wind scaling to workout. You also mentioned I may have to change my weight to compensate for the adjustment I made to get my coast closer to zero. Was that an issue in the profile, or can you tell?
As for the speed jumping around, I was doing CP testing and then recovering by riding around slowly and or in circles/ back and forth so that I would not run out of area to do my next test. Unfortunately I got a flat or almost flat if that is possible and cut it short because it was getting dark.
On another note, what would be the best type of ride to do so that I would have a good ride file to post to check everything out and make sure it is ok or for me to look at myself?
As for the speed jumping around, I was doing CP testing and then recovering by riding around slowly and or in circles/ back and forth so that I would not run out of area to do my next test. Unfortunately I got a flat or almost flat if that is possible and cut it short because it was getting dark.
On another note, what would be the best type of ride to do so that I would have a good ride file to post to check everything out and make sure it is ok or for me to look at myself?
Re: Wind offset
That profile in the ride file I just posted has the corrected wind scaling in it. That is the value I changed based on looking at the overall wind vs. speed values.
The wind scaling value should be left alone for this bike.
The wind scaling value should be left alone for this bike.
Boyd Johnson
http://www.boydcycling.com - high performance carbon wheels and accessories
http://www.boydcycling.com - high performance carbon wheels and accessories
Re: Wind offset
Thanks again for all of your help. After looking at the file I now understand how to check and do the adjustments if I was to ever need to. Again thanks to everyone who helped this newbie along. Now that all is looking good I will do a ride on both bikes and post and then maybe someone could double check them for me to make sure I did them right.
Clint
Clint
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Ratman
- Posts: 92
- Joined: Fri Jan 11, 2008 11:37 am
- Location: North Plainfield, New Jersey (USA)
- Contact:
Re: Wind offset
Rruff has explained his "Out-and-Back"/"on-the-road" method of addressing Wind Scaling issues. Boyd, perhaps you could explain what appears to be your "Profile Tweek Only"/"Ride File" approach so that those of us willing to dive-in to the iBike3 software can give this a shot.
And besides...it would give you more time to ride!
Thanks.
And besides...it would give you more time to ride!
Thanks.
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lorduintah
- Posts: 662
- Joined: Fri Jan 11, 2008 9:37 am
- Location: Plymouth, MN
Re: Wind offset
I seem to notice that the auto-wind on startup is not very effective. By that I mean that immediately bringing up the Cal Wind window shows values not near zero (of course I have cupped over the front of the iBike. Then pressing the center button can even lead to +/- 15-20 mph readings. It takes several attempts to get the cal wind zeroed...
My wind scaling is quite good (about 1.05) , but I find that this extra care to zero is fundamentally an issue.
Tom
My wind scaling is quite good (about 1.05) , but I find that this extra care to zero is fundamentally an issue.
Tom
Re: Wind offset
Is this only when it happens outside? And what are the conditions like? I haven't noticed anything funny there, though I would prefer the option of turning it off. It's quicker for me to zero it manually than to wait for the unit to do it automatically.
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lorduintah
- Posts: 662
- Joined: Fri Jan 11, 2008 9:37 am
- Location: Plymouth, MN
Re: Wind offset
1 - Breezy, but not a temperature that could influence a thermal stabilization problem.
2 - I cup my hand over the port or I can do this indoors (no breeze at all...)
3 - It can be while I am in the car before getting out to put the unit on the bike and I can still get the variations.
4 - Battery is Good.
I also notice that physically covering the air port - like blocking it with a finger and essentially creating a seal - that the cal wind screen can go up to +/- 50 or 60. So it is possible that I am closing off the port too well when trying to zero out the wind. Note - I just did this while sitting at the keyboard and the iBike was sitting on my desk.
Tom
2 - I cup my hand over the port or I can do this indoors (no breeze at all...)
3 - It can be while I am in the car before getting out to put the unit on the bike and I can still get the variations.
4 - Battery is Good.
I also notice that physically covering the air port - like blocking it with a finger and essentially creating a seal - that the cal wind screen can go up to +/- 50 or 60. So it is possible that I am closing off the port too well when trying to zero out the wind. Note - I just did this while sitting at the keyboard and the iBike was sitting on my desk.
Tom
Re: Wind offset
Before the auto cal, someone was using a freezer or zip lock bag to cover the iBike.
I now carry one with me and it usually works quite well.
Russ
I now carry one with me and it usually works quite well.
Russ
Re: Wind offset
I have been having the same problem with my IPro.
I have learn to put the IPro and the Garmin on the bike, spin the crank backwards and turn them both on. Wait till it finds my heart monitor and go back in the house to get my drinks and whatever for my ride, about 5 or 10 minutes. Then just before I take off I re-cal the wind.
It seems it needs time to adjust.
I have learn to put the IPro and the Garmin on the bike, spin the crank backwards and turn them both on. Wait till it finds my heart monitor and go back in the house to get my drinks and whatever for my ride, about 5 or 10 minutes. Then just before I take off I re-cal the wind.
It seems it needs time to adjust.