AeroPod, PowerPod and Newton

A question or 2 on doing a Cal ride.

I have a profile on my Gen 3 iAero.

If I go into set-up/Cal ride and do the Cal ride, Does it store the new wind scaling and riding tilt in the profile on the iBike when you finish the cal ride? if not how would I go about marrying up this Cal ride data with the previous profile?

Thanks for your input

Chris

When you do a new cal ride you will get a new wind scaling and riding tilt. It will also change the aero and friction numbers in your iBike so that you have the same cda and crr as before.

The ride that you do after your cal ride will have a new profile attached. This profile will be the one with the updated wind scaling and riding tilt.

Thank you so much for your help and time. Now it is time to go play.

Chris

I believe you will be able to open up the cal ride and look at the out and back, but you will not be able to save the cal ride as a new profile (because there was no coastdowns)

But, when you ride after doing the new cal ride, that ride will have a profile attached to it and it will be the profile with the new wind scaling and riding tilt. If you have a good cal ride and are confident in your cda and crr measurements, then this is the best option. This is a great option for if you think your wind speed reading might be off (easy to tell with the new absolute wind speed reading in firmware 3.09).

coachboyd wrote:When you do a new cal ride you will get a new wind scaling and riding tilt. It will also change the aero and friction numbers in your iBike so that you have the same cda and crr as before.

The ride that you do after your cal ride will have a new profile attached. This profile will be the one with the updated wind scaling and riding tilt.

CoachBoyd:
First, let me apologize for the length of this post, but I'm utterly at wits end as to how illogically my upgraded GenIII iAero has behaved from the moment I first used it (had no similar trouble with the Gen I or II...). It's been three months now, including countless hours of recalibrating, remounting, sending in files for analysis, etc., etc., and I can honestly say that I'm still waiting to get a ride file that has "plausible" results. Despite the fact that I have a "million" other things that I should be doing other than spending two hours now on this post, I simply don't know what to do any longer than to explain in detail what I'm currently seeing and hope that somebody can provide some explanation or guidance.

I just did a new cal ride because previous cal rides (using the recommended protocols and all done very carefully under the best wind/traffic/road conditions that I could find) with the new Gen III iAero initially produced wind scaling factors around 2.0-2.5, then more recently around 1.0; the tilt factor with my previous iBikes has always been -0.5 and was initially -0.5 with the Gen III, but in more recent cal rides, the tilt correction has been -0.1 or -0.2 with no change in position or equipment (I weigh about 170 lbs, so I'm not a super lightweight, although I do have a slightly more upright riding position than some road bikers to reduce lumbar flexion in an effort to protect my low back). In other words -- the data with the new GenIII iAero has been all over the place, leaving me totally uncertain as to the quality of the power data (I don't have a DFM).

Well, in the tradition of this unit producing unexpected results, I actually did two cal rides today, because, when it said "Go bac" during the first cal ride, even though I turned around and went back in the other direction, it continued to say "Go bac," and something like "turn 180 degrees." It never changed this message all the way back to my cal ride starting point, at which point I didn't see any messages saying that it was processing the data. Finally, for lack of any idea as to what to do, I pushed the center button and it said "Aborted." By the way, when I went into "Download Coastdowns and Calibration Rides" in iBike3 after returning home, it did have a file for this "aborted" cal ride, but I don't know if the data were valid??

So, having had an "aborted" the first cal ride, I felt like I had to redo it. This attempt went without a hitch as far as the messages I saw during the cal ride -- it said "Go bac," and when I turned around, it verified this by saying "bac." It also indicated at the end of the cal ride that it was processing the cal ride data. I have no idea why the unit responded differently on these two back-to-back cal rides, but it's not a confidence builder...

As I was riding back home, I noticed that my power numbers were higher than before doing the two cal rides, consistent with something having been changed automatically by the cal ride process. Upon arriving home, I downloaded the cal ride data. One thing that confuses me is that in "Profile-Edit Profiles..." there are no new entries reflecting today's cal ride(s). The entry for the last profile during which time I did both coastdowns and a cal ride looks exactly the same as it did before I did these most recent two cal rides -- I see no change in the wind scaling or ride tilt, nor do I see a modification of the Aero or Friction values as should have happened per your post above.

However, if I look at the file for the ride home after the two cal rides, under "Tools-Tweak CdA, Crr, Cm...," the CdA and Crr both differ from the CdA and Crr in the profile that was in the iAero when I left the house today. So, according to this screen, despite what you said in the quote above, the coastdowns apparently didn't preserve the previous profile's CdA and Crr.

Just to confuse matters more, if I view the "Tools-Switch Profile After the Ride..." screen, it reports the higher power data reflecting changes to the original profile, but shows no changes in the "Original Aero" and "Original Fric" fields. Furthermore, the dropdown under "Profile that should have been in iBike" doesn't have any new profiles listed to apply.

I don't get it: The CdA and Crr for the ride immediately after the cal ride(s) was apparently changed (even though they shouldn't have been), but there's no evidence of the changes or ways to view or edit the apparently new profile under any of the iBike3 profile-oriented menus (including "Profiles-Edit Profiles...")...or the iBike left arrow screens for that matter. Can you explain these findings? When I go out for my next ride, which values will be in effect, and where can I go in the iBike3 software to confirm the values being used? Why was the CdA and Crr changed in the ride file immediately after the cal ride(s) even though no coastdowns were done? I thought the last set of coastdowns I did were good and should not have been changed, but I don't know how I'd restore them, or even what I'm working with at this point.

Thanks for any advice that you can provide.

Ratman wrote:
So, having had an "aborted" the first cal ride, I felt like I had to redo it. This attempt went without a hitch as far as the messages I saw during the cal ride -- it said "Go bac," and when I turned around, it verified this by saying "bac." It also indicated at the end of the cal ride that it was processing the cal ride data. I have no idea why the unit responded differently on these two back-to-back cal rides, but it's not a confidence builder...

Ratman, the behaviour of the CAL ride changed in the 3.09 firmware, it now automatically detects when you turn around BUT you have to slow down enough, sounds like on your first CAL ride you did not slow down as much as the second attempt.

Ratman wrote: As I was riding back home, I noticed that my power numbers were higher than before doing the two cal rides, consistent with something having been changed automatically by the cal ride process. Upon arriving home, I downloaded the cal ride data. One thing that confuses me is that in "Profile-Edit Profiles..." there are no new entries reflecting today's cal ride(s).

The iBike Software used a unique combination of Aero and Fric values to identify different profiles. In your case the Aero and Fric would have been unchanged and therefore you would be unable to extract a new profile from the ride, even if your tilt and windscaling were different.

2 ways I know of generating a new profile, you can modify the existing profiles Aero or Fric value very slightly and save. This will allow you to extract the new profile from the ride file.

The other method would be to look at the CDA and CRR values for the ride in the left hand Ride Summary Window in the iBike Software, you should see the values that were applied by the GENIII after the CAL ride was completed. You can then use these values to create a new profile, or copy the existing one and modify that. Just change the tilt and wind scaling values until the CDA and CRR matches what is displayed in the Ride Summary Window.

coachboyd wrote:When you do a new cal ride you will get a new wind scaling and riding tilt. It will also change the aero and friction numbers in your iBike so that you have the same cda and crr as before.

The ride that you do after your cal ride will have a new profile attached. This profile will be the one with the updated wind scaling and riding tilt.

Coach Boyd, I agree with Ratman on this one, when I do a CAL ride only, the Aero and Fric values on the iBike do not change, but the CDA and CRR is modified based on new Tilt and Windscaling factors. This is why you see different power numbers before and after the CAL ride. I'm doing another one this afternoon just to make sure I'm not going mad.

Coach -

When I did just a CalRide (CDs and another CalRide a few days earlier on same section of road) - I managed to get very close Wind scaling and tilt error corrections from another set of wheels - that's good as I would expect to have no difference. I guess I had done a data erase as there were no coast down readings and the software gave me a bunch of NaN values (a polite computer responding that there is no number to display) - So I chose to use the profile with the Coast Downs and a previous Cal Ride - but fiddled with the Friction and CdA to get the right slope, a different Crr etc.

Aside from differences in Crr and Fric values for the two wheelsets (Ksyriums and Carbones), it appears that all other parameters are now similar and the Fric and Crr are also reasonable.

So now I can wait and see if firmware 4 really does make some of this a little less complicated if you do things piecemeal.

Tom

Morocco Mole wrote: Ratman, the behaviour of the CAL ride changed in the 3.09 firmware, it now automatically detects when you turn around BUT you have to slow down enough, sounds like on your first CAL ride you did not slow down as much as the second attempt.

Morocco:
Thanks for the tip -- that's probably what happened. Too bad that isn't in the documentation to avoid problems for the user...

Morocco Mole wrote: The iBike Software used a unique combination of Aero and Fric values to identify different profiles. In your case the Aero and Fric would have been unchanged and therefore you would be unable to extract a new profile from the ride, even if your tilt and windscaling were different.

2 ways I know of generating a new profile, you can modify the existing profiles Aero or Fric value very slightly and save. This will allow you to extract the new profile from the ride file.

The other method would be to look at the CDA and CRR values for the ride in the left hand Ride Summary Window in the iBike Software, you should see the values that were applied by the GENIII after the CAL ride was completed. You can then use these values to create a new profile, or copy the existing one and modify that. Just change the tilt and wind scaling values until the CDA and CRR matches what is displayed in the Ride Summary Window.

coachboyd wrote:When you do a new cal ride you will get a new wind scaling and riding tilt. It will also change the aero and friction numbers in your iBike so that you have the same cda and crr as before.

The ride that you do after your cal ride will have a new profile attached. This profile will be the one with the updated wind scaling and riding tilt.

I think I understand method #2, but I'm still confused because (1) don't the coastdowns determine the Cda and Crr? So if you feel that your original coastdowns were good and it's the wind scaling and tilt that need to be remeasured (through a "stand alone" calibration ride), shouldn't you be keeping the Cda and Crr "as is" and changing the "bad" windscaling and/or tilt numbers in the profile (this seems to be what Coach Boyd is saying above...)? I assume this would produce new Aero and Friction values which I'm should theoretically render more accurate power data. Do I have that wrong?

(2) Also, I seem to recall that Rruff (can't find the exact thread at the moment) has advised against changing Friction (or Aero?) singly as they are derived/extracted from the same coastdown data and therefore are mutually dependent. I think he said that changing Friction, for instance, requires an unknown amount of compensation in Aero to be entirely true to the original coastdown data. If that's so, then if to sustain your Crr value, for example, you end up having to change the Tilt and Friction values, it seems you're left not knowing how to tweek the Aero value to compensate and be true to the Aero-Friction relationship derived in the original coastdown set. I hope I'm capturing Rruff's comments accurately...can you verify if I'm being accurate? The subject is very confusing.

To approach this from another direction, regarding method #1, when you say "extract a new profile" (from the post-calibration ride ride file), is this a function on one of the iBike3 screens? I see "Extract" as a choice under "Profiles-Edit Profiles..." but there are no ride files listed in the file list, and when I try to "Import" the post cal ride ride file, it says "No Profile found." How do you do the extraction of the profile from the post calibration ride ride file?

Thanks for your comments and time, Morocco!

Ratman wrote:I just did a new cal ride because previous cal rides (using the recommended protocols and all done very carefully under the best wind/traffic/road conditions that I could find) with the new Gen III iAero initially produced wind scaling factors around 2.0-2.5, then more recently around 1.0

I noticed a similar thing with my Gen3... the wind scaling would jump around but always be high... but it has since settled down at ~1.0.

Ratman wrote:
To approach this from another direction, regarding method #1, when you say "extract a new profile" (from the post-calibration ride ride file), is this a function on one of the iBike3 screens? I see "Extract" as a choice under "Profiles-Edit Profiles..." but there are no ride files listed in the file list, and when I try to "Import" the post cal ride ride file, it says "No Profile found." How do you do the extraction of the profile from the post calibration ride ride file?

The purpose of changing the Fric or Aero values is to allow the iBike 3 software to let you extract the new profile from the currently downloaded (active) post CAL ride ride file. Like I mentioned before, it's the combination of these two values that the iBike 3.0 software uses to identify a profile, it ignores all the other values, so even if you have a different Wind Scaling or Tilt it thinks it's the same profile. This is under the profiles- edit profiles option you mention above. You only need to change one of the values in the existing profile by the smallest possible amount eg .001 , so it won't effect the accuracy at all, but it's enough to let you create a new profile. Basically what you end up with is a new profile with the existing Fric and Aero values (the output from your old coastdowns), but it has had the new CAL ride applied to it. Let me know if you want some screen shots.

The aero and friction values are what the power is based on for the calculations in the iBike. If you didn't need a wind scaling value, aero and friction would be the only two things you would need to get accurate wattage. But with the variances in units, placement of the iBike, and rider position, each unit will have a different amount of wind entering the wind port at speed. This is the wind scaling, and the byproduct of the aero value divided by the wind scaling is your drag coefficient (cda).

On the other side, you get a total friction number when doing a coastdowns. With the old Gen 2 and 3 units however, it would look like you were riding down a slight hill all day until riding tilt came about. When you subtract the riding tilt from the overall friction you get your rolling resistance (crr).

I was under the impression that if you had a profile in your iBike and you did another cal ride it would give you new wind scaling and riding tilt numbers, but then it would change the aero and friction values to keep cda and crr consistent (since you know those didn't change). I'll have to look into this and test this out.

Thanks for offering to test this, Boyd, because I think what you're looking for from a redo of a cal ride is correct, but I don't think the iBike applies the cal ride data as you have assumed. I'd also really appreciate your response to the assertion that I alluded to above, made in a previous thread that I've now found (and as it turns out, was in response to one of your posts this last February...):

Quote
"Re: The calibration ride (GenIII units)

Postby rruff on Mon Feb 23, 2009 12:45 pm

coachboyd wrote:What you can do for your crr number is to set that number in your profile based on your typical road conditions. You can guesstimate a riding tilt number and change the friction values to get crr correct.


The only issue with this is that Aero and Fric are extracted from a total "drag"... so if you change your Fric value manually, then Aero needs to change in the opposite direction... some unknown amount.

Extracting accurate Aero and Fric values via the CDs is actually a difficult task. That is why you need to do a *lot* of CDs and take an average. Fric is the smallest factor so has the most chance of error. I think it would be nice to have the option of selecting a Crr (and Fric) and having the software use this to calculate the best fit for Aero."
End Quote


So, is rruff's concern valid? To restate the issue, due to the way Aero and Friction are derived, if an edit to a profile causes Aero or Friction to change, does a compensatory change need to be applied to the other factor so as to remain consistent or "in sync" with the original set of coastdown data? If so, how specifically, should we go about implementing the necessary compensation?

There's been a lot of discussion on this forum regarding "tweeks" to a ride profile. If rruff's comments are valid, then it seems we need to be a lot more knowledgable and strategic about going in and changing profile values if the calibration and related power measurement process is to truly be data driven and not merely an exercise in "tweeking" a profile to obtain power numbers that we "think" look good.

For many of us (especially those of us living in congested, urban areas) it's extremely difficult to conduct coastdowns and particularly calibration rides under optimal, or even adequate conditions. In my area of New Jersey, there are no roads available that go 2+ miles without encountering (take your pick): sharp turns, hazardous intersections, humongous hills, lousy pavement, unrelenting high-speed traffic around the clock, high/gusty winds, unavailability of a place to do a proper wind offset, unexpected construction, getting a flat tire mid cal ride...just to name a few (no joke...I've encountered all of these issues!) Having the knowledge and tools to make valid "tweeks" in ride profiles and to be able to add new cal ride data (when it becomes possible to collect it) to previously-created profiles based on good coastdown data would be invaluable.

Ratman wrote: Extracting accurate Aero and Fric values via the CDs is actually a difficult task. That is why you need to do a *lot* of CDs and take an average. Fric is the smallest factor so has the most chance of error. I think it would be nice to have the option of selecting a Crr (and Fric) and having the software use this to calculate the best fit for Aero."

Somebody's been getting insider information about one of the features of firmware 4.00 - hint hint