DCRR (Dynamic Coefficient of Rolling Resistance) - PowerPod Lite V3 - Gravel / Mixed surface riding questions - New user

Post Reply
chbowman101
Posts: 3
Joined: Wed May 26, 2021 9:34 am

DCRR (Dynamic Coefficient of Rolling Resistance) - PowerPod Lite V3 - Gravel / Mixed surface riding questions - New user

Post by chbowman101 »

Good day!

I've poked though a lot of posts and there are lots of "confirm my calibration" posts, and some mention of offroad / gravel / MTB riding, etc. I've not found this specific question though on how DCRR functions (and if it specifically is on ALL current firmware versions of the PowerPod, specifically the PowerPod Lite v3).

My goal is to use my newly purchased PowerPod to consistently (honestly not all that concerned about "accuracy", more about consistency) measure output so that I can pace properly over long climbs, and mixed surface rides. In reading through how PP deals with mixed surface, it looks/sounds like DCRR was put in place to more quickly compensate for road/trail surface changes. My questions are around how I should expect this to manifest in real world conditions and what I should expect in regard to limitations, etc.

So, as mentioned above, I'm not all that concerned if the PP says I'm pushing out 200w or 220w or 180w .... as long as its consistently off in a predictable way so that I can use the data to pace myself better (I suck at doing it via heart rate). I want to maximize how consistent that error is. I'm not interested in needing to validate frequently (or even monthly) a calibration just to gain another 2-4% accuracy. I'm a plug and go kinda guy and I accept the fact that my devices may be a little off due to that (as long as they are consistently off). 90% of my rides are mixed surface that include asphalt, smooth to rough gravel and single track mtb trails (all on the same ride).


Direct questions:
1) Does DCRR function on the PP Lite v3 (and at what firmware version). If not, what upgrade cost is there to obtain this.
2) Is DCRR really the answer to consistently measuring power output over varied terrain on the same ride or am I barking up the wrong tree and should be looking at more manual adjustments via isaac or something (I'm hoping this (lots of manual adjustments in isaac) isn't the case, cause I really don't want to fool with it). I tend to do events that are remote, meaning I don't have a feel for the course conditions other than a GPX file that the organizers push out. So I can't exactly put in new settings for each ride anyway that would be meaningful in any way.
3) I assume I should be calibrating on standard (mostly smooth) asphalt following the "card" instructions that are packed with the power meter. My goal to be to use this same stretch of road to perform any new calibrations should the unit need it after updates / etc). My goal again is consistency. Is this a false assumption?
4) How quickly should I expect the DCRR function to respond to changes in terrain? Noting that what I'd read said that it was measuring 800 times per second but I'd assume there is some computational lag involved. If transitioning from asphalt to gravel (or the opposite) should I expect the reported power to my Garmin head unit to be accurately compensated for within a few seconds, a few minutes, 15 minutes, etc?


This is my planned operational process. Is this within the "it'll work well in terms of providing consistent measurements" category?

1) Secure the PP Lite v2 via "out front" garmin/gopro mount and fixated in such a way that it will not be moved on a regular basis.
2) Wake up my ANT+ speed (on front wheel) and ANT+ cadence sensor (on pedal arm) sensors. Turn on Garmin 520. Turn on Heart Rate monitor.
3) Pair PP to Garmin and follow basic calibration process outlined on the setup card in the box riding on smoothish asphalt in a wind protected (treed) area with almost no traffic (low speed ride up a slope until it reaches 100w(%) in the seated position not changing gears.


Process for regular rides:
1) wake up cadence and speed sensors
2) click the PP button once
3) turn on Garmin and confirm connection with sensors and heart rate strap.
4) go ride and not think twice about calibrating again on a regular basis and trust the numbers I'm seeing to be consistent ("right or wrong" doesn't matter too much to me, just that they be precise (ie, consistently write or wrong in the same direction over varied terrain)).



Sorry for the long post ... but these are the things I think about and rather than bug the email support folk (who have been great by the way), I figured I'd stick this out there to see who else follows this general line of thought, and, to see if the developers feel this is the intended use case for this power meter and that my expectation are in line with reason.


Thanks!!! :D
Velocomp
Velocomp CEO
Posts: 7793
Joined: Fri Jan 11, 2008 8:43 am

Re: DCRR (Dynamic Coefficient of Rolling Resistance) - PowerPod Lite V3 - Gravel / Mixed surface riding questions - New

Post by Velocomp »

Lots of questions!

1) DCRR is a standard feature in all units, including PPL. It responds within 5 seconds to measurable differences of road roughness.

2) DCRR does a good job of responding to large changes in rolling resistance, such as those found when going from smooth asphalt to chip seal.

3) As you point out, the most important thing to achieve is consistency of results. I would not recommend adjusting ride files manually in Isaac; that introduces a level of variability that likely will be unpredictable from ride to ride.

4) Your startup procedure is the same as mine :D
John Hamann
chbowman101
Posts: 3
Joined: Wed May 26, 2021 9:34 am

Re: DCRR (Dynamic Coefficient of Rolling Resistance) - PowerPod Lite V3 - Gravel / Mixed surface riding questions - New

Post by chbowman101 »

Great, thank you for the information!!


Now that the easy stuff is out of the way ....

You mentioned that DCRR does a good job at large changes in surface. I use the same bike for road and gravel and single track .... and , well everything pretty much.

Should I be fooling about using the PowerHouse App to customize my weight/bike weight, wheel size, bike type, etc.? I change out wheel sets to something with low rolling resistance road only tires) if I'm doing a fondo type event (all asphalt) or something?

I also toss the racks on and run panniers for camping at times. How should I best account for the massively increased drag involved with panniers (sometimes I run front and rear, sometimes only rear ... sometimes bike packing bags ... etc).

DCRR sounds like its geared at estimating resistance based on road "feel" ... and I'm guessing its not going to really tell the difference between a tire change? To be honest it prob. doesn't matter all that much on the tire changes, but still would be nice to know.

The MUCH bigger aspect though is the rack/pannier situation. The bike gets wide, and heavy. Should I be using the PowerHouse phone app at that point to edit the "Bike Type" (assuming I would pick "mountain bike or 29er MTB as it seems like the least aero choice), and overall bike weight? There is also NOT an overall circumference on the "Tire Circumference" that matches my wheels (my gravel wheels are 700c with 47c gravel rubber) and there seems to not be any 29er tire options (I run MTB tires on the gravel bike (2.1's) when I do a lot of single track or events that are just awful in terms of road quality, as mud, single track, trail, etc).

Should I be even fooling with the PowerHouse app (which oddly isn't free on the Apple app store, its 99 cents)? Or should I just follow the calibration procedure above and forget about the rest? If I understand how opposing force PM work ... it seems weight and aero profile would be a really big deal, but maybe in practice its not as much as I'd think.

Comments?? =)


(and thank you!!)
User avatar
lorduintah
Posts: 642
Joined: Fri Jan 11, 2008 9:37 am
Location: Plymouth, MN

Re: DCRR (Dynamic Coefficient of Rolling Resistance) - PowerPod Lite V3 - Gravel / Mixed surface riding questions - New

Post by lorduintah »

I would think that for some of these changes - if you are expressing hyper curiosity or wanting exact differences based on bike configuration - you might consider changing the speed sensor for each of the big changes you have expressed concerns about. That way, the panniers and weight/CDA impact might be reflected in the power differences required for these kind of changes.

If you are really diving into this as far as you seem to be - PPL should be upgraded to a regular PP, too.

The PP device recognizes some of these configuration changes - if you change Speed sensors - so a different speed sensor for wheel size changes, one for the camping configuration.

Use an average set of values in each if you are changing road types. Whatever becomes the most economic path, but still sensitive to what ever you want out of the tool.
chbowman101
Posts: 3
Joined: Wed May 26, 2021 9:34 am

Re: DCRR (Dynamic Coefficient of Rolling Resistance) - PowerPod Lite V3 - Gravel / Mixed surface riding questions - New

Post by chbowman101 »

Thanks for the response lorduintah.

I'm not sure I'd really call it "hyper curiosity", really just trying to learn the best way to use the tool at this point. Knowing that the "different bike" detection is handled through sensing differences in Speed Pods makes perfect sense. I'd suspected that but hadn't dug into it. It also tells me a lot about how I may want to proceed with my processes for handing changes.

I spend maybe 70% of my time on this bike "naked" (no racks, etc) maybe 20% packed up in various ways and probably the rest of the time with road wheels on it. The speed sensors are cheap (I use the Magene ones) so a second one for my "road" wheelset would be in order perhaps, just not sure its worth the effort and cost to do so.

Knowing that the differences are primarily chosen (or recognized) through detecting the speed sensor ID and activating that profile is very handy to know, thank you again for pointing that out.

I think my strategy for now will simply be to "recalibrate" on the occasions that I swap bike configs and update the bike weights via the PowerHouse app on my iPhone. Still curious if the "Bike Type" in the Powerhouse Settings actually moves the calculation for aero drag any. In reality, when I toss the rack and panniers on the bike its always a little different anyway, so practically speaking , I'd probably want to do a 5 minute calibration ride again anyway.

As long as I remember to calibrate on the same stretch of road near my home each time (shouldn't be a problem as I tend to do a quick ride the day or so before a venture out to make sure I've not done anything silly like forgetting to anchor my bags down correctly ... don't ask) I think I should get acceptable precision for my desires.

Again, thanks for the conversation everyone!
Post Reply