reading green tilt lines

[travispape]

I thought I would post tilt screenshots from my 3 iBike units for my ride this morning to show their green tilt error lines and how I read them.

The 3 units on my bike:
1. iAero on stem (despite the unit's marking in the photo)
2. iBike with the original accelerometer on the bars (black one on the right)
3. iBike with an experimental accelerometer (white one on left)

(The experimental accelerometer didn't pan out. It performs about the same as the original accelerometer. I have the only iBike with it.)

Units on bike

units_on_bike.jpg (115.39 KiB) Viewed 6487 times

(A gold star to anyone who can figure out what that blue thing is to the left of my bike.)

The following 3 screenshots are the tilt for each of the 3 units.

iAero on stem mount

68mi_stem_iAero.png (49.21 KiB) Viewed 6479 times

old iBike (original accelerometer) on bars

68mi_bars_old_iBike.png (47.35 KiB) Viewed 6476 times

iBike (experimental accelerometer) on bars

68mi_bars_experimental_accelerometer.png (45.65 KiB) Viewed 6479 times

The barametric pressure at the closest weather station was stable for the duration of my ride, ranging from 1010.4 mbar to 1011.1 mbar.

Observations:

* 2 of the 3 results are good and the 3rd wasn't terrible. Here are the tilt errors:
1. +0.05 points (+4.7 W)
2. +0.03 points (+2.8 W)
3. +0.15 points (+13.1 W)
Either I miffed on the tilt calibration for unit #3 or it wasn't completely seated in its mount until I started riding. Anyway, this kind of tilt error is unusual for me but I thought I would show it anyway.

* At mile 16, the tilt error increased for all 3 units. Something very slight happened to the bike to change the tilt of the front-end. Often when I see something common to all 3 units like that, I can trace it back to something that happened on the road, but this time I don't remeber anything special that happened at that point in the ride. I was on a road that has some buckles.

The miffed tilt cal on unit #3 plus the increase of tilt at mile 16 caused its larger overall tilt error.

* Starting at about mile 42, unit #2 went nose-down some. I'm not sure why, but it could have shifted down in the mount. Another possibility is that its circuit board could have flexed some. Unit #2 is on the right and this is when I started riding North. Unit #2 was out of my shadow and would have heated up more than the other units due to the sun. I'm just wondering if the section of the circuit board where the accelerometer is soldered could have flexed in such a way to change the tilt a little. I don't know--this is just my speculation.

* For about the first 2 miles of the ride while I was warming up, I rode on the hoods and you can see the negative tilt error that that caused in all 3 units. Again, all 3 units have a negative turn in the tilt error at mile 46-48, which is when I was in a county park to get water and again I rode on the hoods. There are also several speedbumps that I hop over. Sometimes that causes a change in tilt for all 3 units, but not this time. You can see some tilt spikes where I was hopping.

* No problems with vibration for the iAero, but the 2 iBike each had just a little trouble.

* I don't know why there is a glitch in the iAero tilt data at mile 27, but that is where I stopped at a gas station to get Gatorade. It could be that the altimeter data was a little lala when I first turned that unit back on.

This is probably way more than you wanted to know about my green lines, but there it is.

Travis

[racerfern]

Louisville Slugger pitching base. But is that your bike holder?

[travispape]

Louisville Slugger pitching base. But is that your bike holder?

Yep, might as well put it to work when it's not pitching.

[rruff]

Unit #2 was out of my shadow and would have heated up more than the other units due to the sun. I'm just wondering if the section of the circuit board where the accelerometer is soldered could have flexed in such a way to change the tilt a little. I don't know--this is just my speculation.

I've wondered about that too... there is definitely some differential heating when the sun is out, and it's possible that any warping that this causes would effect some units more than others.

[Russ]

Travia,

your:
Observations:

* 2 of the 3 results are good and the 3rd wasn't terrible. Here are the tilt errors:
1. +0.05 points (+4.7 W)
2. +0.03 points (+2.8 W)
3. +0.15 points (+13.1 W)

Are much appreciated!!!

My observations:

1. Now THAT is a really GREAT dashboard!!!

2. Glad someone has a real practical use for baseball equipment

3. The clear on the hoods tilt increase at mile 42 was of most interest to me.
As the earlier one was not so pronounced and clear. Looking at the old ibike, seems like I would get a .2 degree increase in tilt on the hoods (I chose it for the flat green before after giving me 40' drop in 4 miles), does that sound right?

My bike (bars to hoods) get more like .5 degree negative increase when observed in the kitchen changing positions while watching the tilt screen. I only got .2 difference on my two 'same condition' cal sessions one on bars and one on hoods. My actual rides seem to more reflect the .5 degree, typically. Not sure why I didn't get as much negative tilt on my cal rides!

I examined my most recent 25 mile ride and the two climbs (.2 and .3 km on the hoods) were probaly 8 and 20 meters of additional elevation drop in the green line (lost while going uphill on the hoods). The 10 meter in .3 km was more clearly discernible and works out to 3.3% grade all by itself.. Am I calculating this correctly, using the green line elevation change?

Anyway, the tweeking tips have allowed me to get a very workable profile for my most common ride 25 mile ride. That ride includes two climbs which slow me down enough to switch to the hoods. I have ridden them on the bars just to check the profile and all that.

Bottom line, the - I think - easiest addition to help me the most would be to add an optional tilt correction to the ibike software in with the 'second cda' panel. Nicer still, in the firmware to add the same two (cda nad tilt) changes to use below x speed.

Thanks,
Russ

[Russ]

Ooops I see I typod the second green line elevation drop... Where I typed 20meters should have been 10 meters for the .3 km one.
Sorry,
Russ

[travispape]

3. The clear on the hoods tilt increase at mile 42 was of most interest to me.
As the earlier one was not so pronounced and clear. Looking at the old ibike, seems like I would get a .2 degree increase in tilt on the hoods (I chose it for the flat green before after giving me 40' drop in 4 miles), does that sound right?

Maybe this is what you meant, but you should see your tilt become more negative when you use the hoods. Since your weight is farther away from the stem, there is more torque causing the iBike to go nose-down. -0.2 points sounds like the right ballpark.

My bike (bars to hoods) get more like .5 degree negative increase when observed in the kitchen changing positions while watching the tilt screen. I only got .2 difference on my two 'same condition' cal sessions one on bars and one on hoods. My actual rides seem to more reflect the .5 degree, typically. Not sure why I didn't get as much negative tilt on my cal rides!

It might be because you aren't pedaling in the kitchen. Your force on the pedals results in your arms bearing less weight. 0.5 points of difference for the hand positions would be getting on the big side compared to what I normally see.

I examined my most recent 25 mile ride and the two climbs (.2 and .3 km on the hoods) were probaly 8 and 20 meters of additional elevation drop in the green line (lost while going uphill on the hoods). The 10 meter in .3 km was more clearly discernible and works out to 3.3% grade all by itself.. Am I calculating this correctly, using the green line elevation change?

Looks right.

Anyway, the tweeking tips have allowed me to get a very workable profile for my most common ride 25 mile ride. That ride includes two climbs which slow me down enough to switch to the hoods. I have ridden them on the bars just to check the profile and all that.

Bottom line, the - I think - easiest addition to help me the most would be to add an optional tilt correction to the ibike software in with the 'second cda' panel. Nicer still, in the firmware to add the same two (cda nad tilt) changes to use below x speed.

Thanks for the feedback.

Travis

[R Mc]

Interesting discussion--

as to the tilt going out on climbs, I've seen this on my own files. Now it makes more sense why it's happening.

Travis, you wrote that switching from to the hoods should make the tilt more negative--is this assuming that the switch is from aero-bars to hoods? (If that was clear in the thread I apologize for skimming). If it's a switch from the drops to the hoods, I don't see how that makes much of a difference in tilt.

But what about a switch from the drops (or hoods) to the classic middle-of-the-bars climbing position [granted this doesn't appear possible with the passengers on your bars]? And what if that switch of hand position is accompanied by a pronounced shift rear-wards on the saddle?

Seems to me as if moving backwards on the saddle for more climbing leverage could account for a slightly positive tilt shift.

[travispape]

I'm doing all my riding in the drops with occational excursions to the hoods, so I'll need others to chime in about their experience comparing the tops and aero bars. Also, you can get the answers from your own ride data by analyzing your own green tilt curves. Let us know what you see.

The reason that moving from the drops to the hoods increases tilt is becuase your weight is farther away from the steering tube, i.e. a longer lever.

[alienator]

Interesting discussion--

as to the tilt going out on climbs, I've seen this on my own files. Now it makes more sense why it's happening.

Travis, you wrote that switching from to the hoods should make the tilt more negative--is this assuming that the switch is from aero-bars to hoods? (If that was clear in the thread I apologize for skimming). If it's a switch from the drops to the hoods, I don't see how that makes much of a difference in tilt.

But what about a switch from the drops (or hoods) to the classic middle-of-the-bars climbing position [granted this doesn't appear possible with the passengers on your bars]? And what if that switch of hand position is accompanied by a pronounced shift rear-wards on the saddle?

Seems to me as if moving backwards on the saddle for more climbing leverage could account for a slightly positive tilt shift.

Travis summed it up pretty ok. Consider that your center of gravity is located somewhere in the lower third of your torso. What center of gravity means is that if you put all of your mass at that point, the effect of the gravitational force on that mass would be the same as it is with your body. Now, if you think about how your torso moves when you go from drops to hoods, or hoods to tops, or summat, those movements cause your center of gravity to rotate backward around a point inside your pelvic cavity. It doesn't take a huge movement like that to cause a measurable shift in tilt. The effect of shifting backwards in the saddle at the same time as you change from hoods to tops, for example, is even more significant, as the change in CG as a result of that lateral (backwards) has a linear effect, while changing positions on the bars has a sine dependency which at it's maximum is only one. At the changes in torso angle you're talking about, the sine dependency will be much smaller than linear dependency of the shift backwards.