Is ground speed supposed to be zero?

[jparker]

After downloading the ride file I've noticed that wind offset is always zero but the ground speed is usually a neg. number and rarely a positive number and I've never seen zero unless I play around with it to make it zero. I had one file from a race and the file read that I had a -3.7 and it made a 51w difference in my avg. and more than that on my max. When I zeroed it out my wind offset went to -16.1. This is my extreme file but most of my files read between -.3 to -1.9. Am I supposed to zero the ground wind to get more accuate readings I'm just not sure. CoachBoyd if you read this this was the race at the BMW test track in March when it was so windy. I spent alot of the time off the front and attacking so I wasn't drafting the whole race by any means. My avg. watts were 219 but when zeroing the ground wind it went to 270w which was close to my norm. power of 297w. Which is correct 219w or the 270w? Thanks for any input from anyone.

[coachboyd]

If your average ground wind is always negative (even when you ride by yourself), then your wind scaling might be slightly off. If you do another calibration ride you will get a new wind scaling number and you should be good to go. If you are happy with your current cda number, then you can change your aero number in the new profile that will be created for you when you do the new calibration ride. Changing the aero number will keep the wind scaling the same, but change the cda.

And yes, I do remember that race at the BMW. I remember getting blown off the track three times.

[rruff]

You can check your wind scaling at any time by doing another Cal ride, or using the procedure described here, which I think is slightly better:
http://www.ibikeforum.com/viewtopic.php?f=6&t=867

[jparker]

Thanks for the replies and ideas I'll be doing them both to get as close as I can with all my values.