Newbie Calibration Question

[chrus101]

Hi,

Just did my first calibration ride and coast downs. When I load the data into the software I get the following numbers:
wind scaling 0.563
tilt -0.3
(weight 203 lbs, wheel circ 2096)
However for Aero, Fric, CdA & Crr I get NaN and consequently "Accept Profile & Sent To iBike" is greyed out and can't be used.

I did fifteen coast downs (!) with aero values ranging from 0.134-0.180 (these seem low from what I have read) and all Fric vals @ 7.68 (presumably due to Crr being held fixed?). These are the values in the "coast-down results" list.


What am I missing here, thanks for any help.

Cheers, C

[racerfern]

Hover your mouse over the Accept... button. Wait a second or two and the reason for the refusal to save and send to iBike will be displayed.

Let us know what the error shows.

[chrus101]

Hi Fernando,

Says "Aero out of range, Fric out of range, Crr out of range"

I've double checked all the input data, i.e body weight, total weight etc. and can't find anything obviously wrong. mount is rock solid.

Cheers, c

[racerfern]

Actually with a wind scaling that low those aero numbers make sense. I'm going to defer to either Velocomp or CoachBoyd on this one. My wind scaling is even lower than yours so I'm not sure what the problem is. Silly question; Are you sure you're not ignoring the coast down data by looking at DFPM power or something like that?

[R Mc]

Have you chosen which crr figure to use? (There's a choice in that box--and until you choose which one, the info. stays greyed out, I think. It's been a day or two since I've done a profile).

[chrus101]

Hi,

Fernando: My coast downs results are listed in the "coast-down" window not the "iBike + DPFM" window.
I was wondering about my cal ride. I was crook yesterday so just did one in a local tree lined suburban street. Had some wind (not strong) and no car problems. Had one stop to cross a busy road. Not sure how far from ideal this was.

R Mc: I Chose "Crr Fixed" from the IB3 software as that was how I had the iBike set to record. I know what you mean by having to choose this.

I am still assuming that I am missing something obvious.

Cheers,
C

[racerfern]

Even though you can't send it to the iBike you can still save the calibration file. Upload it here and we'll have a look.

[chrus101]

Hi,

If it helps I have included today's ride file as well as the calibration file.

Cheers,
c

[racerfern]

I switched from Crr Fixed to Crr Adjusted and got some pretty good numbers. I'm not sure why you would have to switch from Crr Fixed to Crr Adjusted and then switch back. Give that a try.

Are you on a TT bike or a very aero position and/or are you using tubular tires? I ask because the adjusted CdA seems low as does the Crr.

Anyways, let's see what CoachBoyd has to say.

[chrus101]

Hi,

Just a standard road bike with Shimano Dura Ace CL7850 clincher wheels. Riding with hands on the hoods.

Thanks for you perseverance Fernando.

Cheers, C

[chrus101]

Hi,

I see what you mean about the missing cal values appearing when Crr is set to "Crr adjusted". I assume this is the setting you use when the third coast down procedure is used and the iBike "EST Fric" is set to NO. Just confirming I had it set to YES and "Fric" = 55.

Is my "estimated aero" as determined from my weight (79 kg) and height (178 cm) and riding position (hoods) the same as the CdA value (0.362 m2) that is listed in the ride file previously attached? If so, are these values considered close (0.362 (calculated) vs 0.310 (coast down determined))?

I will go and do some more coast downs but with the Crr not fixed and see what i get.

Cheers,
c

[racerfern]

@chrus101

Try this attached profile, it should give you good results. I did lower your CdA somewhat based on the ride you provided. Sorry, I don't have an explantion as to why the profile would not be created.

After saving and sending the profile to your unit, simply do a tilt calibration and you should be good to go. Reply back if you have comments or concerns.

[coachboyd]

The profile that Fernando provided makes the results look very good. Sorry I was away for a few days there.

[chrus101]

Thanks Fernando & Coachboyd. Excuse the delay, I have been offline for a while. I am in the process of altering my bike fit and may be getting a new frame (looks like a crack in my existing frame!) so will prob soon be doing some more cal rides and may be back for more help.

Cheers, c

[chrus101]

Just noticed that FW404 has been posted (which I have downloaded)....any chance the problem I was having is related to the "improved CdA measurement (iAero only)" tweak?

Cheers, c

[coachboyd]

No, the improved iAero cda measurement is for when you have your iAero paired up to another DFPM (power tap, srm, quarq) and are viewing the live drag coefficient as you ride.

I'm not sure why your numbers were grayed out at first, but when you switched back and forth through the different methods of processing coastdowns (crr fixed, iBike setting, crr adjusted), it became available again.

[travispape]

Hi,

Just did my first calibration ride and coast downs. When I load the data into the software I get the following numbers:
wind scaling 0.563
tilt -0.3
(weight 203 lbs, wheel circ 2096)
However for Aero, Fric, CdA & Crr I get NaN and consequently "Accept Profile & Sent To iBike" is greyed out and can't be used.

I did fifteen coast downs (!) with aero values ranging from 0.134-0.180 (these seem low from what I have read) and all Fric vals @ 7.68 (presumably due to Crr being held fixed?). These are the values in the "coast-down results" list.


What am I missing here, thanks for any help.

Cheers, C

By the way, I found the bug that caused this problem and fixed it for the next release. The issue is that you had one very unusually short coast-down that was getting through the filter into the calculations. As Boyd mentioned, all you had to do is change the Crr setting to Crr Adjusted and back to work around the issue, but in the future it should work first try.

Thanks for reporting it in.

Travis

[chrus101]

Thanks for the message, Travis.
My coast downs were done on a section of road that was flat while accelerating and started going up during the actual coast-down. Sounds like it may have been a bit too steep.

Cheers, Chris

[coachboyd]

For coast downs I like to use a bowl shaped road. I use the downhill to get up to speed without having to stand and wrench on the handlebars. Then I will let the flat to uphill section slow me down to the 8mph. I have found that I get the best results when a coastdown lasts for 15-25 seconds, and the bowl shaped road lets me go back and forth in the same section.

It shouldn't be a problem if you coast to a stop up a hill unless it gets really steep in which case you'll still be in the same gear as when you got up to 20mph and that's going to be tough to start pedaling again going uphill at 8mph.

[chrus101]

Thanks Coachboyd, just need to find one of those spots now.

Checked the gradient of my coastdown spot as i rode past yesterday, ca. 1-1.5 % incline as getting up to speed and ca. 1.5-2 % incline during coasting.

Cheers, Chris

[prs]

I have just upgraded from the Sport to the Pro, so I am new to the iBike Software. I went out this morning and did a new cal ride and lots of coast downs. I have attached the Profile File and a subsequent ride file. I was hoping that some of the members could take a look at the two files and give their thoughts on my calibration and set up.

Thanks - Paul

4-9-10-Profile.ibp

(334 Bytes) Downloaded 208 times

iBike_04_09_2010_1540_21_Miles.csv

(859.73 KiB) Downloaded 209 times

[coachboyd]

Just took a look at the file and everything looks really good on your profile. Your wind are watts are right in line with what I would expect and you look to be getting great results!

[prs]

Thanks Coach!

Having everything set up well means I have no more excuses - I will have get out there and get some serious training started.

Paul