Anticipated troublesome ride conditions?

[.:Tim:.]

Glad to see this new PowerPod Forum is up!

I'm still learning about what to expect out of the powerpod, and am curious if there are any conditions where we know the powerpod will suffer/report erroneous figures, based on carryover of the technology from the Newton/prototype testing?

e.g. today I took the unit out on my non-DFPM bike. Before the ride, I uploaded a modified user profile to the unit for this bike that made adjustments for user height and weight, and during the ride, I observed long periods of "0" watts [edit] accompanied by prolonged braking & wacky slope readings (see below).
there were two key factors to the ride that might present trouble vs. the user profile- (1) slightly damp conditions that may have been spraying the unit with water from the front tire and (2) a modest 5-10 MPH tail wind. this was an out & back effort, so the tail wind turned into a head wind, and the numbers were still low...


I'm excited to get the most out of the powerpod and realize it's potential, and a clear understanding of the known limitations will greatly reduce apparent frustration.


**edit: added ibike file and replaced screenshot of the data from Garmin recording with Isaac

[Morocco Mole]

Hi, you mentioned this was an out and back ride, one thing I notice is that the elevation constantly drifts upwards throughout the entire ride. If I go into "analyze route" and select "Ride ended where it began" the software will correct the TILT drift and your numbers look much better. You can quite obviously see the head wind v tail wind in the plot of the entire ride. The question now is what is the cause of the TILT drift, from memory of my time with the iBike I think that changing atmospheric conditions can be a cause but was only minor compared to your example. I can also see the TILT is definitely wrong at the beginning of the ride but after 5 minutes this was auto corrected, it all seems to go wrong again after 10 minutes, did something happen at this point such as it started raining? If the TILT value stored in your profile is incorrect then you will have issues the first 5 minutes of every ride if you have sent the profile to the powerpod. I extracted your profile from the ride and it looks pretty good, so assuming the PowerPod has now corrected the initial TILT you should not have to send the profile again, in fact it would likely cause you an issue. I would love to see your next ride file but make sure you do not send the profile again. I asked John some questions regarding TILT behavior and his answers are below which may help some people.

QUESTION - There is no way to do a manual TILT calibration with the PowerPod, I assume the initial calibration process determines TILT and then every time time you ride the TILT is verified during the first 4-5 minutes of the Ride?
ANSWER -YES

QUESTION - Does the PowerPod recalls the previous TILT setting and then just verifies and updates if required each ride?
ANSWER- YES

QUESTION - Once you have performed the initial calibration ride is there a way to force the PowerPod to do a calibration again, eg the Solid Yellow light followed by the flashing yellow light?
ANSWER - THE ONLY WAY IS TO CHANGE TO AN UNUSED PROFILE, OR TO SWITCH TO A SPEED/CADENCE SENSOR WITH A DIFFERENT ID. OTHERWISE THE PP WILL JUST UPDATE ITS PREVIOUS VALUE.

QUESTION - As above, if I move to a new bike with new sensors how do I initiate a calibration again?
ANSWER - WHENEVER YOU CHANGE SPEED/CADENCE SENSORS THE PP WILL THINK YOU HAVE CHANGED BIKES, AND IT WILL AUTOMATICALLY PUT ITSELF INTO CALIBRATION MODE.

QUESTION - What is the timeout interval before the PowerPod goes to sleep? I have noticed it sleeping after stopping at traffic lights for a couple of minutes
ANSWER- I WILL CHECK, BUT IT SHOULD BE ABOUT 10 MINUTES.

QUESTION - What is the best way to achieve a more accurate calibration of the powerpod. Should I just edit the profile with my actual weight then do a traditional out and back ride with analysis in Issac?
ANSWER- YES, THAT IS THE PERFECT WAY. WE ARE TRYING TO KEEP THINGS SIMPLE FOR PP USERS BUT YOU CAN DO EXACTLY WHAT YOU SAY TO TWEAK THINGS FOR BEST RESULTS.

Regards
Jim Robinson

[Morocco Mole]

Having another look and the "Ride ended where it began" actually only contributes about 30 watts average difference to the original file. The "Analyze Route" option on it's own is making the major changes and removes all the power dead spots from the ride. Have attached the TILT plot anyway but something weird going on here.

[Morocco Mole]

I have done a comparison between my profile and the profile I extracted from the ride posted above. Overall there is not much difference between them but I did notice in the attached ride the profile does not have a TILT value stored and is showing as empty. Again I am looking for advice from the Velcomp techs, but if you have sent this profile to the PowerPod before a ride then it will be significantly out until the auto tilt calc correction is performed. If you look at my profile it shows ***** in the TILT field, when I was tweaking I choose "get from device" and accepted(saved) this before sending back to the PowerPod. This should have stored the previously corrected TILT Calc from the last ride in the profile as a known good state. Not sure this is the cause of the drift unless starting from such a bad TILT may have been outside a range which can be auto corrected?

Comparison below - my good profile is the BH one.

[Velocomp]

I looked at your ride file and some of its hidden data.

What I suspect is going on is that your PowerPod is not rigidly attached to the mount; that is, when you are descending quickly or hit a bump, the PowerPod rotates slightly in its mount, subsequently causing power to drop to zero until it automatically readjusts itself.

Please make sure to place your PP in the mount, then push (rotate) it forward from the rear, so that the PP hits the stops in the mount, then tighten the screw so that the PP cannot rotate.

Try another ride and please post your ride file.

[Morocco Mole]

John you mentioned the following in this thread http://www.ibikeforum.com/viewtopic.php?f=64&t=3359

"Also, for some reason the "soloist" profile you copied is NOT a calibrated profile (tilt is "empty")."

As I noted above in the screenshot of the profile, the TILT is empty. Is this not an issue?

Thanks
Jim Robinson

[Velocomp]

The user changed his rider weight using Isaac.

It's possible that, if not done correctly, the riding tilt can be reset to empty. This is OK; on the next ride, after 5 minutes of riding, the tilt number will be recalculated and inserted into the profile.

[.:Tim:.]

Hi Jim & John,

sorry for the lengthy delay in getting back to you on this- I've been riding with this occassionally over the last couple of months, but have been short on time to try and figure it out.

attached are a few ride files, the two more recent ones are on this bike.

From what I can tell, we left off with questions about how secure my PP was mounted to the bars. When I install it on the bike, I follow the recommended instructions (pushing it forward in the mount while tightening the screw) and crank it down to what I feel is a reasonable, secure tightness that shouldn't jeopardize the integrity of the plastic. Can you please have a look at the two most recent files and let me know if they show this defect?

My most recent rides with the unit have shown lower than anticipated power values, with some peculiar activity:
when I am descending, it shows zero or near zero numbers no matter how hard my effort it
when the elevation inflects and I am going up, the power numbers jump up immediately- almost like there is a switch that flips- do I have some tilt setting that are making this thing go bonkers?

Have a look at the data and let me know where I should go- I would like to start using the PP in earnest to guide training as the racing season begins.

Happy to plan a call/short webex if that is easier than explaining via the forum.

Thanks!

Tim

[Velocomp]

Here is what is going on:

1) If you look at your ride files you will see a consistent tail wind. This is indicative of an improper, low wind scaling setting, which would cause low watts, particularly on downhills

2) Using the "Edit/Edit Profiles/Extract From Ride File" command I got your wind scaling factor, which is 1.15. The factory value is 1.4 or 1.7, depending on mount location; somehow, your factor was lowered too much.

3) I adjusted the wind factor back to the closer value of 1.65; once doing this watts increase and wind readings look normal.

4) You'll note that, on your 4/12 ride, when descending you now have watts.

Please load the attached profile into your PowerPod and all should be well.

[.:Tim:.]

Thanks John!

I'll give it a whirl and report back tomorrow!

[.:Tim:.]

Hi John,
Thanks for this- I repaired the files and poked around at them. I noticed that my elevation values are showing remarkably negative values.
Does this impact any aspect of the device?
[Edit] found this thread that deals with elevation adjustments post hoc -http://ibikeforum.com/viewtopic.php?f=93&t=3487




Thanks!

Tim

Screen Shot 2016-04-14 at 6.24.01 AM.png (166.92 KiB) Viewed 7623 times

[Velocomp]

Elevation measured by a barometric pressure sensor located inside PowerPod. Elevation is therefore dependent on weather conditions.

Though the absolute starting elevation can vary, the elevation profile and gains are spot-on.

You can correct the starting elevation of the ride in Isaac using "Analyze/Analyze Newton Settings..." command.

[.:Tim:.]

Thanks John!

And, for the record, here's a ride with the corrected settings. looks much better than before. [Edit: incredibly windy day!]

a couple of questions:

1.) I see in Newton that the CdA is a static setting- is this optimized in the original calibration? or is it a "living" value that PP will update every ride?

2.) Do you have ~ values for CdA summarized anywhere, e.g. what are normal for certain positions/bikes? I know my position could use some improvement and I'm curious how it stacks up, especially between my bikes with relatively different frame geometries.

3.) Do you have any recommendations to further improve my profile? Out & back, coast down, et c.? Are there instructions for doing this on PP?


Thanks for your time!

Tim

[Velocomp]

1) CdA is static and is related to rider's height, weight and ride position. Most riders ride in the same position most of the time.

2) We don't have a CdA table that we publish

3) If you do an out and back ride, you will be able to fine-tune your wind setting even more.

4) Coast downs aren't available in PowerPod.