Newton Analyze Calibration

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rstrom
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Newton Analyze Calibration

Post by rstrom »

I did a solo ride today with my Newton and decided to see what would happen if I used the Analyze / Check Calibration feature of hte software.

The Newton has been successfully tilt calibrated and I have done two calibration rides, the second one being which is being used is a 3+ mile ride which I believe was a pretty good calibration ride - straight out and back for 1.7 miles each way on a pretty flat road.

I was surprised to see a significant difference in the Check Calibration and the actual calibration.
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The modified results change the climbing from 176' to 19'. I also used My Tracks GPS on an Android phone for the ride and it reported 152' of climbing which I know is much closer to reality than the 19'. This was an out and back route.

Some feedback on this would be greatly appreciated.

Thanks,

Robert
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lorduintah
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Re: Newton Analyze Calibration

Post by lorduintah »

When you run the check calibration,it is really important to see what is changing that made the difference.

In your case, you might observe that the TILT went from -0.4 to 0. This looks like the most significant shift of anything in the analysis - a small delta to wind scaling which is not likely to throw everything off much. Are you sure about your choice of Crr? The choices are fairly good in selecting the road and tire combinations, so I would expect that you made your choices correctly - just asking if you looked at all of them.

So your original calibration was effectively off quite a bit in tilt set up.

I would think you could use the changes suggested and then check everything again on a new ride, where you should have only some small changes that should not make any differences - especially when taking in to account day-today variations.

Tom
rstrom
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Re: Newton Analyze Calibration

Post by rstrom »

lorduintah wrote:In your case, you might observe that the TILT went from -0.4 to 0.
Yes, I definitely noticed that. So what does this mean to me? I did the tilt calibration and got a good tilt. Does this mean that it wasn't a good tilt?
lorduintah wrote:Are you sure about your choice of Crr?
I have no idea if I'm sure about the Crr. I didn't choose it. If this has to do with the tire choices and road surface choices, yes, I think I selected them correctly. Also riding on the hoods.
lorduintah wrote:your original calibration was effectively off quite a bit in tilt set up.
Why would it say good tilt and then be off so much? I put the wheel up against a wall and then flipped the bike and put the other wheel up against the wall and then repeated again. It doesn't seem possible for this to be a bad tilt.

:? :o I thought the Newton was supposed to be a piece of cake to setup / configure? :o :?

The friction was also considerable different 8.974 > 5.753

The first calibration ride that I did the friction was over 12. My previous iAero friction number was between 9 and 10 so I thought that the 8.974 number was valid (the road I did the calibration ride on was fairly smooth and a fair number of roads that I ride on are fairly rough chip seal).

I must admit that I'm a bit dismayed since I'm experiencing some of the same calibration issues that the iAero had and my understand was that it would be much more simple to get everything calibrated correctly.

Don't get me wrong, I know that I'll like it once I work through this, but it is a bit frustrating. Am I doing something wrong (I don't think so)? Believe me I was pretty careful / meticulous in performing the tilt and the cal ride (2 of them on two different days).

Robert
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racerfern
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Re: Newton Analyze Calibration

Post by racerfern »

I've got a couple of thoughts:

1) The tilt cal has nothing to do with the tilt that went from -.4 to 0. Tilt cal is zeroing the unit so that it shows zero when the bike is level. The tilt in a profile is the adjustment made because as you ride on a perfectly level road the weight of your body on the bars tends to make the iBike point downhill, hence the -.4. Riders in a TT position can get closer to zero tilt adjustment because they can even pull up on the bars when they're extended.

2) Average Crr is probably around .005. At .0071 you're definitely too high unless you have some cheap 700x32 or 38 tires. You might want to click off the original tab and switch to the Estimated tab. At that point put .005 for your Crr.

3) Aero and fric numbers are just that, numbers. They're the result of a certain CdA divided by a certain wind scaling. In and of itself Aero and Fric are nothing more than the means to complete the math equations.

4) Finally, I'm not sure how you got some of the numbers you got into the Newton to begin with, but I suggest you start from scratch. The process is really quite as simple as inputting your relevant data and doing a cal ride. You can do the cal ride first and then connect to Isaac and click Device > Device Setup, follow the prompts to enter weight, riding position, etc.
Fernando
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lorduintah
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Re: Newton Analyze Calibration

Post by lorduintah »

The tilt can be way off if the altitude was changed after a startup. I have had this happen a couple of times on the iBike after I reset the altitude. The sudden change in elevation and the calculations can lead to some very weird estimates. I would suggest that you do check your altitude - but before you start pedaling - like just after the Newton is turned on.

As far as the Friction shift - many of the parameters are not independent and a change in one will change at least one other. It is likely that the slope change is making an impact.

I agree with Fernando that a fresh start is going to clear the slate of any unintentional entries. YES - it is easy to get a calibration in the Newton - pilot errors are inevitable though (intended or not)

Tom
rstrom
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Re: Newton Analyze Calibration

Post by rstrom »

I'll probably/may try a fresh start, but I've got to say that the questions are very straight forward .... I answered them ... don't think I'll answer them any differently this time around. Then perform a tilt calibration then a cal ride. It's not rocket science but I've never had any (on this or previous iAero) come out right without having to tweak, and tweak again.

I accepted the changes and may ride with it this way for a while and use my next solo out and back to check the calibration again and see what it says.

Is the check calibration function something that you can use several times to fine tune your calibration?

Thanks,

Robert
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racerfern
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Re: Newton Analyze Calibration

Post by racerfern »

Here's how I go about doing a new setup, whether it's a new iBike or a new bike:

I immediately go out and do 4 cal rides, all of them early in the morning before the wind picks up. I happen to have an ideal location where a bike trail runs flat for one mile, so I do an out/back on that. Then I have a shorter bike trail that intersects the first one. I go back and forth until the two miles is complete, which I also do twice. These four cal rides only take about 30 minutes to complete.

Now I download the 4 rides and take the average wind of the four. From there I create a profile with the Isaac software but I just save it as a profile. I modify the wind scaling to be the average of the four cal rides, save the profile and send it to the unit.

I realize I'm fortunate in that I have ideal geography for cal rides but the principle can apply wherever you do your cal rides. I don't do coast downs, instead I use .0045 for Crr based on the fact I use Hutchinson Tubeless Fusion 3 tires. They roll like a dream even at 80psi.
Fernando
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lorduintah
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Re: Newton Analyze Calibration

Post by lorduintah »

I have several rides in since getting my Newton. I have checked the calibration after every one and the only time I have actually accepted the changes was the first one after the cal ride (most of that change was wind scaling with some friction adjustments (presumably because there were no coast downs done and not much else.) Ever since then, the changes proposed are either really small or declared as insignificant by the software. I never did a coast down with the Newton, but with the iBike it felt to me to be an absolute necessity. I still do find that zeroing the wind offset to be necessary - but that's only on startup - not several times a ride.

I too have tubeless tires - Shimano DAs with Specialized tires (supposedly made by Hutchinson, too.) They really are outrageous compared to any of the other tires I ride - wheels aren't bad, either.


Tom
ScottChapman
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Re: Newton Analyze Calibration

Post by ScottChapman »

That's actually a really interesting idea...

Is it better to go out and get a good calibration ride, including coast downs, or just do analyze calibration after the rides until the changes it proposes are small?
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Russ
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Re: Newton Analyze Calibration

Post by Russ »

ScottChapman,

One way that it is better to do the cal ride and then tweek with checks is that you can use the cal ride file as a real ride file. The coastdown files are a pain to try to piece together into a usable file for the rest of a ride to use in WKO+ :-)

I have done four cal rides, three in my normal bars position and one on the hoods. The wind was only close to ideal on one of them. Anyhow, the checks/tweeks on my two real rides have landed wind correction very near the average of my three better cal rides. I do use an RWS so the wind on my hoods ride is one of those better ones, although the tilt is greater. The RWS out front keeps the change in my position from affecting the wind readings.

My tilt on the bars is -.4 and on the hoods is -.7 so I have to compromise my profile to seek an average since I actually ride both positions (and some standing, etc). The iBike seems to handle all that very well on the road.

With three of the cal rides I did three CD's and with the fourth I did seven. The day with seven was the best for wind and four of the CD's were nearly identical and the average of all seven was ony .002 different from the four by themselves!

I like to experiment with the thing to get a better feel for what is going on.
Except for that preference, probably just ride and tweek is just fine!

Russ
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