"Auto Analyze" distorts? Slope and power numbers inaccurate?

[dtrousdale]

I uploaded to the iBike 2 software some intervals I did this morning, and it looks to me like "Auto Analyze" is doing something screwy to my data. Before going on my ride, I did everything as instructed: including reset Offset to 0, reset tilt, checked battery, set correct altitude, etc. Then I did three intervals of 6:30 minutes each and tried to average over 300W per interval. I did each of the intervals on exactly the same route: a hill that has a maximum slope of about 16-17% according to my realtime observations. After applying "Auto Analyze," it shows slopes of between 27.7% and 37.5% for each of the three intervals. Prior to applying "Auto Analyze," the data showed a Max slope of 18.4%. Needless to say, this must distort my power data immensely. The power data prior to applying "Auto Analyze" looks much closer to what I observed in realtime which seemed to me to be well above averaging 300W but with no big spikes. It does not make sense to me that the slope numbers would change so dramatically upon applying "Auto Analyze" since iBike measures that "directly" rather than inferring it, right?
I've noticed something like this in another way, too. Every so often (about 6 times since purchasing my iBike last December '07, including my first iBike as well as the replacement unit I received after the tilt function on my first unit went completely kaput), huge power and slope spikes appearing right at the beginning of the ride (I'm talking 2k to 3k Watt spikes). I'd, of course, like to think I am capable of that but there is no way since I was just warming up and there were no conditions such as slope that would or wind explain it. So far, I've just been snipping this off so it does not distort my over all records in WKO+, but now I'm beginning to wonder if there is not a more serious problem here. I've had a few other such spikes more well into a ride file, but I've been ignoring them and not looking at these changes to the slope data that I'm now paying attention to. Let me say again, I am meticulous about following all the recommendations prior to a ride: reset offset, reset tilt, etc.
Could it be that my Profile is corrupted?

ADDITIONAL NOTE: I forgot to include that post-Auto Analyze, interval #1 had a Max 763W power spike that corresponded with a 37.5% slope, interval #2 had a Max 757W power spike that corresponded with a 27.7% slope (again, exactly the same hill), and interval #3 had a Max 1138W power spike that corresponded with a 30.8% slope (same hill).

[Site_Admin]

I'm a little behind due to some beta testing, but send me a file and I'll have a look. ALWAYS send me a file, and ALWAYS export your Profile that was used so that I can see that as well.

Finally, everyone, remember the mantra:

1) Leave it outside for 15 minutes while you do your other pre-ride stuff so that the sensors can reach ambient temps and pressures.
2) ALWAYS perform a Tilt cal and wind offset cal before every ride.
3) ALWAYS check the tilt cal before you head out.

This will maximize your accuracy and consistency, and will yield a better ride experience.

[Ratman]

Finally, everyone, remember the mantra:

1) Leave it outside for 15 minutes while you do your other pre-ride stuff so that the sensors can reach ambient temps and pressures.

Richard:

I noticed today that after leaving my iBike outside for 15 minutes, due to direct sun exposure, I suspect, the unit reported a temperature of 92 degrees, while the air temperature was probably in the high '60s or low '70s. Is that kind of temperature elevation from direct sunlight OK, or should I seek out a shaded area in an attempt to keep the iBike's temperature closer to the air temp?

Thanks!

[travispape]

Richard:

I noticed today that after leaving my iBike outside for 15 minutes, due to direct sun exposure, I suspect, the unit reported a temperature of 92 degrees, while the air temperature was probably in the high '60s or low '70s. Is that kind of temperature elevation from direct sunlight OK, or should I seek out a shaded area in an attempt to keep the iBike's temperature closer to the air temp?

Thanks!

What is important is to get the internal temperature of the iBike to match the riding temperature before you do the wind offset cal, so that 92 degF in direct sunlight is a problem. Yes, get it in the shade when you sit it outside. And note that if you are lucky enough to ride in the 70s, that is close enough to room temperature that you don't have to worry about the outdoor soak time.

Travis

[travispape]

I uploaded to the iBike 2 software some intervals I did this morning, and it looks to me like "Auto Analyze" is doing something screwy to my data....

Did you get your issues resolved? Send me your ride files and I'll take a look at it. travispape at yahoo.

Travis

[Ratman]

Richard:

I noticed today that after leaving my iBike outside for 15 minutes, due to direct sun exposure, I suspect, the unit reported a temperature of 92 degrees, while the air temperature was probably in the high '60s or low '70s. Is that kind of temperature elevation from direct sunlight OK, or should I seek out a shaded area in an attempt to keep the iBike's temperature closer to the air temp?

Thanks!

What is important is to get the internal temperature of the iBike to match the riding temperature before you do the wind offset cal, so that 92 degF in direct sunlight is a problem. Yes, get it in the shade when you sit it outside. And note that if you are lucky enough to ride in the 70s, that is close enough to room temperature that you don't have to worry about the outdoor soak time.

Travis

Thanks for the clarification, Travis.

[travispape]

Travis
For example, the air temperature might be 50, but if it's sunny, the black iBike may show 60+ degrees. It will then slowly drop down to actual temperature if you encounter cloudy conditions.

I don't think you would see that big of a temperature disparity. As long as you have the iBike mounted where it gets good wind exposure--which it has to be to work correctly--the convection effect will trump the solar loading.

In general, the small temperature changes during the course of a ride are not the main issue. The thing to be avoided is doing a wind offset with the internal tempature of the iBike still near room temperature when you are going to be doing your riding in colder conditions. This will be less of an issue as we head into summertime.

Travis

[tyhaar]

I'm a little behind due to some beta testing, but send me a file and I'll have a look. ALWAYS send me a file, and ALWAYS export your Profile that was used so that I can see that as well.

Finally, everyone, remember the mantra:

1) Leave it outside for 15 minutes while you do your other pre-ride stuff so that the sensors can reach ambient temps and pressures.
2) ALWAYS perform a Tilt cal and wind offset cal before every ride.
3) ALWAYS check the tilt cal before you head out.

This will maximize your accuracy and consistency, and will yield a better ride experience.

Tilt cal and wind cal before every ride? I understand the wind cal but I thought that was what the profile for your bike was for? The auto analyze also for me after doing 2 intervals at 290-300 watts @7:30 minutes tonight reduced the average all the way down to the 260's? That's a big difference of real time vs. software analyzing the data. The averages realtime were 303 and 293 respectively before downloading to software.

I did do a wind cal about 10 minutes after bike was outside, but I did forget to set the altitude to 130 but changed it in the software later. Lots of things to remember with a hr. of daylight left after work Its to bad the computer does not have a home altitude setting to remember when you reset it for riding. I know my Ciclosport computer had this feature and was nice not having to reset the altitude everytime to ride from the house.

I just checked the tilt and was correct but did another one and was the same results. Doing this do I have to do more coast downs and another 4 miler?

[travispape]

Tilt cal and wind cal before every ride? I understand the wind cal but I thought that was what the profile for your bike was for?

At least check the tilt cal. If you have the same two spots on your floor, you will learn what the slope should be in each direction after you do the tilt cal. Check the next day and see if it is the same as yesterday. If it is usually the same slope day-to-day, you can take your chances and skip it if you want.

Wind offset is temperature-dependent, so if the temperature is the same as your previous ride, you can probably roll the dice and skip it. Just understand that if you skip these that we'll have much less sympathy if you later come to us with accuracy issues. Fair enough?

The auto analyze also for me after doing 2 intervals at 290-300 watts @7:30 minutes tonight reduced the average all the way down to the 260's? That's a big difference of real time vs. software analyzing the data. The averages realtime were 303 and 293 respectively before downloading to software.

I did do a wind cal about 10 minutes after bike was outside, but I did forget to set the altitude to 130 but changed it in the software later. Lots of things to remember with a hr. of daylight left after work Its to bad the computer does not have a home altitude setting to remember when you reset it for riding. I know my Ciclosport computer had this feature and was nice not having to reset the altitude everytime to ride from the house.

I just checked the tilt and was correct but did another one and was the same results. Doing this do I have to do more coast downs and another 4 miler?

The 130 ft of elevation error is not that big of a deal--it certainly would not account for the power change in the post-processing.

If you are consistantly seeing that the post-processing reduces your power by about the same day-to-day, it is very likely that the cause of your problem is that you had a bad tilt calibration on the day you did your profile. If you send me one of your ride files with a big drop in power, I can look at it for the tail-tell signs. Send it to travispape at yahoo.

Travis

[tyhaar]

At least check the tilt cal. If you have the same two spots on your floor, you will learn what the slope should be in each direction after you do the tilt cal. Check the next day and see if it is the same as yesterday. If it is usually the same slope day-to-day, you can take your chances and skip it if you want.

Wind offset is temperature-dependent, so if the temperature is the same as your previous ride, you can probably roll the dice and skip it. Just understand that if you skip these that we'll have much less sympathy if you later come to us with accuracy issues. Fair enough?

Fair enough... I checked the tilt and like I said was OK. Wind cal I adjusted later when I got over to the course I do my workout to let the unit adjust to the temps. I did put the bike outside for 10 minutes even before I saddled up. Just to ease my mind I'm going to re-do the whole calibration of the setup with my race wheels for accuracy.

I would change the instructions for setup from the video's with Richard Wharton saying tilt cal was not required before each ride. I was only following the instructions from the video's and pdf manuels....

Thanks....

[Site_Admin]

Yeah, it's old. The video, that is.

I'm old, too. OldER, that is.

Tilt and wind before every ride. Sort of like Hail Mary's and rubbing that prayer thing on the door paneling at your Jewish friends' house. Make it a ritual.