Calibration Questions

[babyboomer]

I finally got around to calibrating my Newton. I drove out to a local lake around which there's a 5-mile paved road. I'll spare you the details, but when I got home and tried to check the cal ride, I was interrogated by a dialog that, among other things, admonished me about the presence of a breeze, as well as whether I gave adequate time for the unit to become acclimated. Can I assume that the presence of this dialog is an indication that Isaac has already found problems with my calibration ride?

I will admit that prior to the ride my Newton sat in my vehicle for several hours, during which the interior temperature reached 86 degrees Fahrenheit. However, it did sit outside of the vehicle for several minutes (approx. 10) before I actually started riding. Even after I took the Newton out of the vehicle the reading continued to rise, eventually peaking at 91 degrees. I ignored it for most of the ride, but an occasional check revealed that it had started to plummet. By the end of the ride it read 55 degrees - approximately 20 degrees low!

I can do better acclimating the unit, but about the wind, I'm not so sure. I guess I could cup my hand over the port during the wind calibration, but I've seen posts indicating that might not be advisable. Although today is supposed to be my day off, I'm going to try another cal ride this evening. I'll probably take a lap around the lake before I start the calibration ride. If I continue to have problems, I will attach a ride file to my next post.

Edgar

[Velocomp]

Please post a ride file.

[babyboomer]

Here is the ride file.

[racerfern]

The dialog isn't really an interrogation; consider it more like a confirmation that you followed the good practices recommended. In your case you didn't get good results and a couple of things could explain this.

1) Temperature acclimation is not as critical for the Newton as for previous generations but when you're looking to create a profile that you'll use for quite a while, I recommend the unit be properly acclimated.

2) Your wind scaling is way off so I suggest after acclimating the temperature that you do a wind offset to zero the unit. Yes, it is OK to cup your hand over the unit. Try to do it where there is no wind (even if you need to jump back into the car for a few seconds).

3) The "check calibration" functions suggests your tilt is not set properly. So just double check it. The reason it suggests the tilt is off is because the uncorrected tilt shows as positive tilt and that is very unusual since it normally only happens on time trial bikes and even then not very often.

Performing a cal ride is not such a big deal but making sure you've dotted the "i"s and crossed the "t"s, is what makes your cal ride a successful one that will yield excellent results.

[KimG]

Fernando,

How do you know when you have the Newton+ dialed in. I think I've done everything correctly; the power Figures seem right (when compared to the effort I think I'm putting out), but when I "Check Calibration" I get wild swings in the differences meter. So I guess my question is how do you check your work when it comes to doing a calibration of the Newton+

Kimball

[racerfern]

Let's say your CdA is .355 (or whatever) as created by the FAST SETUP procedure. Now you turn on CdA in the RACR screen and if you have a good wind scaling you'll get CdA in the .35 range. If you consistently get CdA readouts in the .40 range, your wind scaling is low. If you get readings in the .30 range your wind scaling is too high.

Note that the CdA numbers can vary depending on traffic, wind gusts, etc. I'm talking about generalizations. A bunch of numbers one way or the other will tell the story. Don't drive yourself nuts over these numbers (there are plenty other things in life to drive you crazy) and don't chase the numbers creating different profiles. Pick a profile, do your fitness test based on the profile and train by that profile. If you start to exceed the FTP on future tests, it's time to raise your FTP. Consistency is the key.

[KimG]

Oh I agree about not chasing the watts number. I'm more concerned that if the number says is 200 watts that it will always be 200 watts with the same effort. I also ride motorcycles and there is always someone that likes to boast that his setup cranks some huge horse power numbers when it's really the torque that the engine produes that does the job (all it is is bragging rights).

Like I said earlier I was a bit worried when I do "Check Calibration" and see that the needle appears to swing wildly over to the scale from day to day (I ride the same route daily) with little more than the wind changing direction and/or speed for the given afternoon. Thanks again I'll try he RACR mode and report back when I have some results.

Kimball

BTW one more question; I have a Garmin 500 that picks up the wattage values from the Newton. I use the Garmin to load data into TrainingPeaks WKO+ and the Garmin Connect website. Is this wattage number on the Garmin a true representation of the effort; or do I have to go through the Isaac SW analysis and use the csv files generared by Isaac?

Thanks again...

[racerfern]

Two things:

Check calibration is VERY sensitive. You might see a swing of the needle two-thirds up the scale but that's not really all that much. Things really are that sensitve. So because you see a swing that seems to indicate a huge difference, it may not be all that much in the scheme of things. Again, don't fret because the needle is in the yellow. And don't check a calibrated profile with another calibration check as you might see the slightest of changes and begin to wonder. Just follow the process and ride.

If you're set with a good profile you pre and post analysis watts will be nearly identical. So yes, the data captured by the 500 will be spot on. However if you haven't followed the procedure for a good profile then you could have differences between pre and post analysis. In that case the Garmin wattage is suspect.

I habitually merge the Garmin data into my power data from the Newton because the Garmin can drop data points and mess things up. Merging in Isaac is another step but it only takes a minute and gives more reliable numbers.

[babyboomer]

The dialog isn't really an interrogation; consider it more like a confirmation that you followed the good practices recommended. In your case you didn't get good results and a couple of things could explain this.

1) Temperature acclimation is not as critical for the Newton as for previous generations but when you're looking to create a profile that you'll use for quite a while, I recommend the unit be properly acclimated.

2) Your wind scaling is way off so I suggest after acclimating the temperature that you do a wind offset to zero the unit. Yes, it is OK to cup your hand over the unit. Try to do it where there is no wind (even if you need to jump back into the car for a few seconds).

3) The "check calibration" functions suggests your tilt is not set properly. So just double check it. The reason it suggests the tilt is off is because the uncorrected tilt shows as positive tilt and that is very unusual since it normally only happens on time trial bikes and even then not very often.

Performing a cal ride is not such a big deal but making sure you've dotted the "i"s and crossed the "t"s, is what makes your cal ride a successful one that will yield excellent results.

I've performed three more calibration rides, each of which I've attached to this reply. This time I did notice the "bad cal" after each attempt. I performed one tilt before the first calibration ride, and a wind calibration before each. I will admit that the tilt I performed before the calibration ride last Sunday was a little shoddy - even though the Newton accepted it. On both days the wind has been calm. Regardless, I shielded the port before each calibration. I haven't even looked at the files, because I don't know what the numbers mean, but I'm wondering whether I can ignore Newton's assessment and apply one of these files.

[racerfern]

The first two cal rides yield almost identical results. For some reason the third one is different.

I would take the first cal ride, use the Check Calibration function. Switch the CdA tab do Estimated so it shows your riding position, height and weight and leave your Crr at 0053. Send it to the iBike and you're done. BTW, the first calride yields a wind scaling of 2.863 and the second one yields 2.862. It doesn't get better than that. When all is said and done your CdA should be at .389.

I'm not sure why you get the bad tilt warning because it looks pretty good. So you might want to do one more tilt calibration just to be sure, but that won't change the profile at all. Also if you haven't done a fitness test you need to do that to establish your FTP. Right now your FTP is set at 80, so a twenty minute test will give you an idea of where you stand. It doesn't matter if you come up with a number of 125, 150 or 200. The key is to do your fitness test, carry on with your training and in a few weeks do the fitness test again, same location, same profile. Keep things consistent and you should be just fine. You'll see your numbers improve.

If you get stuck on something just let us know.

[babyboomer]

The first two cal rides yield almost identical results. For some reason the third one is different.

Yep. The first two were performed over the same course. The third one was performed over a different course.

Thanks again.

[KimG]

Let's say your CdA is .355 (or whatever) as created by the FAST SETUP procedure. Now you turn on CdA in the RACR screen and if you have a good wind scaling you'll get CdA in the .35 range. If you consistently get CdA readouts in the .40 range, your wind scaling is low. If you get readings in the .30 range your wind scaling is too high.

OK I went into RACR screen and turned CdA on (or at least I think I did ). The Newton+ documentation says I should look on the Power Screen; but CdA does not appear (or maybe I just don't know what to look for). What am I missing; or should I be looking for that value someplace other than the Power Screen

Kimball

[babyboomer]

I'm not sure why you get the bad tilt warning because it looks pretty good. So you might want to do one more tilt calibration just to be sure, but that won't change the profile at all. Also if you haven't done a fitness test you need to do that to establish your FTP. Right now your FTP is set at 80, so a twenty minute test will give you an idea of where you stand. It doesn't matter if you come up with a number of 125, 150 or 200. The key is to do your fitness test, carry on with your training and in a few weeks do the fitness test again, same location, same profile. Keep things consistent and you should be just fine. You'll see your numbers improve.

Nag nag nag! Okay, I'll do a fitness test! Considering my current state of fitness, it will be more like a fatness test - something I hope to transform over the next few months.

Edgar

[Russ]

I too have now done a number of cal rides and a bigger number of check cals.

I find the following seems to be the case.

1. Good Tilt cal is a little more sloppy now, it seems to accept several tenths off.
This does seem to affect the cal ride somewhat.

2. It appears that the Newton(+) is more sensitive to wind changes during the cal ride than the Gen III was. This is also the case for rides for which you do the check cal.

So I have had several cal rides that converge on a wind scale value and several tweeks that also are quite close (as close as .002 several times) for that value.

So currently I check my ride with check cal and if the wind scale is off much more, I cancel out and then do the correction selections. Then choose wind changed as I currently am thinking that the check cal value is a good indicator that the average wind was offset by changes.

In my case, with the RWS, I am not sure if temperature change is affecting anything.

John's comments about wind cal not needing redoing is looking spot on when I make sure to check the unit in a well protected place.

This brings up a point to consider. If you can do a great wind cal at home and then ride to your cal site but take too long and it insists on a redo, then you loose accuracy, no?

Russ

[Russ]

Where I said this:

"So I have had several cal rides that converge on a wind scale value and several tweeks that also are quite close (as close as .002 several times) for that value."

Now with more experience I have to say the .002 was a statistical fluke

I can say with fairly high confidence that plus or minus .025 is almost no difference.

In fact, with the value I run now, the check calibration feature deviates up or down as much as ~.025 at times. The higher deviations (as much as .025) result in less than
1kh changes in my average wind speed.

Russ