AeroPod, PowerPod and Newton

Hey guys. I've been riding with a PT Pro+ wheel for about a month now and love the real-time CdA data.

However, power readings from the PT fluctuate quite a lot--much more than when using the iBike alone--and that makes holding a watt target difficult for me. I regularly see 50+ watt fluctuations on the bike from reading to reading. Is there any way to smooth this out? I'm not really interested in instantaneous peaks while on the bike; instead, I use it as a pacing tool and leave other analysis for when I get home.

So, any ideas on how to smooth out data from the PT?

We aren't responsible for the behavior of competitors' products

One of the things we did with the iBike is provide smoothing filters that calm down the watts jumpiness. The PT doesn't have those filters and so their readings are, in fact, more varied.

Probably the best thing to do right now is to turn Pin "off" when you're doing interval training. When you do you'll be getting the iBike numbers on your screen, which have the smoothing.

You can display the power on your Powertap by using a 2 or 5 second interval averaging. The fluctuations on your power tap can be reduced by holding a steady rpm, rather than watching your wattage. As you realize, the power displayed by your powertap is the real thing, while the IAero is a calculated figure.

samisrour wrote:You can display the power on your Powertap by using a 2 or 5 second interval averaging. The fluctuations on your power tap can be reduced by holding a steady rpm, rather than watching your wattage.

My cadence and effort are steady: 110 rpm @ 200 watts, not even a tempo effort; just a steady pace on a flat road. And I still get huge moment-to-moment power swings. Do others have this issue? Is the 5 second interval averaging on the PT available when displaying on the iAero?

samisrour wrote:As you realize, the power displayed by your powertap is the real thing, while the IAero is a calculated figure.

Don't even get me started on this. Both the PT and iAero give calculated figures. The PT isn't necessarily the "real thing"; it just uses different sensors and more simple equations to give it's calculated results.

I have the same issue. It's related to the fact that the PT hub calculate power every second, not at every crank revolution. But the PT computer have the option to smooth the displayed numbers. So if this option exist in their computer, I guest it's something feasible for the iBike since he got a bigger processor (I guest!).

I wrote a post about it few month ago:

http://www.ibikeforum.com/viewtopic.php?f=25&t=656

I know that Velocomp should not be responsible for the behavior of competitor's product. But I think that issue (averaging the power displayed) is the last thing to do to convinced PT owner to upgrade their computer to iAero. As Norm said, without this it's very difficult pace your effort. So I'am actually thinking about to get both computer on my bike for this single issue even if I hate the idea to put this ugly yellow thing on my bike.

Velocomp wrote:One of the things we did with the iBike is provide smoothing filters that calm down the watts jumpiness. The PT doesn't have those filters and so their readings are, in fact, more varied.

Is there any chance we could have the iBike smooth the Pin display while it continues to record the raw Pin data in the ride file?

Velocomp wrote:Probably the best thing to do right now is to turn Pin "off" when you're doing interval training. When you do you'll be getting the iBike numbers on your screen, which have the smoothing.

I understand and that makes sense other than loosing the continuous CdA. I guess I'm really wanting a new TT-focused power display screen that's based on the user interval screen: avg power at the top; current smoothed power in the middle (perhaps alternated with distance); and on the bottom alternating time, HR, cadence, and CdA.

I actually have a love/hate relationship with the alternating data, especially when there are more than two alternating figures. The data I'm looking for seems to never be on the screen when I glance down so I tend to either glance up and down rapidly until I get the data point or I watch the screen until it comes up. Neither seems like a very good practice, but I guess I'll just have to live with it like everyone else until the iBike gen iV comes out with it's wide-screen, data-galore display.

I thought about including cadence for the Usr intervals, but then it go to the same point that you just brought up, too much information circling through. . . it'd be like trying to watch CNN with a stock ticker at the bottom.

The one thing we have to try and do is make the iBike screens easy to use for everybody. If we tried to make every request happen, we'd end up with a computer about the size of a mini laptop on our handlebars. As for your request of seeing cda when you are time trialing, the best way to do this is to find your optimal position before the time trial. Find what you can hold that is the most aero and where you can put out the most power. If you are holding that position then you will not be gaining or losing any time during the actual time trial. But the prep work needs to be done ahead of time so you go into the race knowing what your cda is.

coachboyd wrote:I thought about including cadence for the Usr intervals, but then it go to the same point that you just brought up, too much information circling through. . . it'd be like trying to watch CNN with a stock ticker at the bottom.

Roger. I have the same issue, which is why I usually leave CdA off.

coachboyd wrote:As for your request of seeing cda when you are time trialing, the best way to do this is to find your optimal position before the time trial. Find what you can hold that is the most aero and where you can put out the most power.

That's my intention. The PT is on my trainers, so it won't even be available in the actual TT.

As for the prep work, it'd be nice to avoid a lot of trial and error since continuous CdA and Time Advantage are available on the bike. The unsmoothed Pin data from the PT was making it hard for me to figure out the best position while on the bike (trading less power for less drag and more speed), but I suppose I should be watching CdA and Time Advantage instead when fine tuning my position.

Hey Boyd, what's your procedure for finding an optimal TT position? Do you try to adjust it on the road or do you run a series of trials and then do the analysis at the house? Which variables do you try to optimize? (Yeah, we're obviously looking for the best time; but weather and road conditions make it hard to compare efforts from one day to the next.)

coachboyd wrote:The one thing we have to try and do is make the iBike screens easy to use for everybody. If we tried to make every request happen, we'd end up with a computer about the size of a mini laptop on our handlebars.

Here's a data point based on an informal sample. A lot of people I ride with only care about 3 things when on the bike: (1) power, (2) heart rate, and (3) cadence. That would be a really nice screen to have -- all the basic data with no alternating displays. Speed is almost never a concern, so feel free to ditch it if needed.

On the user interval screen, average power changes very slowly so it would be a candidate for an alternating display: CdA perhaps?

Norm wrote:Hey guys. I've been riding with a PT Pro+ wheel for about a month now and love the real-time CdA data.

However, power readings from the PT fluctuate quite a lot--much more than when using the iBike alone--and that makes holding a watt target difficult for me. I regularly see 50+ watt fluctuations on the bike from reading to reading. Is there any way to smooth this out? I'm not really interested in instantaneous peaks while on the bike; instead, I use it as a pacing tool and leave other analysis for when I get home.

So, any ideas on how to smooth out data from the PT?

For info, I was a pretty handy sprinter but decided to move into the booming TT scene. My problem was that I was able to randomly hit 1kW + spikes in races without realizing it and always went way to hard at the start and as a result my pacing skills were abysmal a year ago.

I focused on micro pacing with the best resolution possible with my SRM when doing specific intervals and now I can nail the required wattages and keep my NP and AP within a few watts if required with no more silly spikes in TT's unless I actually mean to do it.

You really have to try and use the PM to tune your RPE and then your pacing will improve. It's hard to do but is worth it as you can go quite a bit faster if you can pace well.

cheers


Steve

Norm wrote:

coachboyd wrote:The one thing we have to try and do is make the iBike screens easy to use for everybody. If we tried to make every request happen, we'd end up with a computer about the size of a mini laptop on our handlebars.

Here's a data point based on an informal sample. A lot of people I ride with only care about 3 things when on the bike: (1) power, (2) heart rate, and (3) cadence. That would be a really nice screen to have -- all the basic data with no alternating displays. Speed is almost never a concern, so feel free to ditch it if needed.

On the user interval screen, average power changes very slowly so it would be a candidate for an alternating display: CdA perhaps?

I'd prefer power with just an indication of whether your above or below average and forget the rest. Too many numbers just gets confusing when your on the rivet. Customized screens would be perfect (well I can wish).

cheers

Steve

I have to agree with Norm. Power, HR, and Cadence, non-alternating would be great as those are how most workouts are prescribed by coaches and training books.

We're looking to see if we can add to 309 a feature that will smooth DFPM readings. Stay tuned...

Velocomp wrote:We're looking to see if we can add to 309 a feature that will smooth DFPM readings. Stay tuned...

Thanks John! Velocomp shows, yet again, that they're the most responsive company in the industry.

Norm wrote:

Velocomp wrote:We're looking to see if we can add to 309 a feature that will smooth DFPM readings. Stay tuned...

Thanks John! Velocomp shows, yet again, that they're the most responsive company in the industry.

The most responsive company with the best cycling computer!

Thanks John!

We have never thought the iBike is perfect so we will never stop trying to make it better. The great discussions in these forums is one of the best ways we have to learn what we can and need to improve.

We have a beta version of 309 with DFPM filtering.

Please email me at jhamann@velocomp.com if you'd like to try it.

Boyd has checked it out and gives it two thumbs up...

Here some observations about the filtering in the beta firmware 309 :

- It's off topic, but I have to say it: The absolute wind speed is great !

- To me, the DFPM filtering in FW309 seem to me a 5 seconds average applied to both the displayed power and the recorded power. There a difference between both and it had been discuss on the google "Wattage" forum. Here's the unanimous response: Filtering displayed power is good since it make pacing effort more easy; Filtering recorded power is not good since it make your raw data less acurate (for example, in WKO, having a filtered recorded (5 sec) data will decrease the 5sec mean maximal power). So having a filtering applied only to the displayed power would be better.

- By the way, the actual smooting of the recorded power make the comparaison between PT and iBike (wih the iBike software) a perfect match... My estimation, half of the small difference between PT and iBike power is simply due to the the more versatile nature of the PT data.

- Now, about the type of filter for the displayed power. I thought first that 5 sec would have been the perfect choice between smoothness and responsiveness. After few ride with the FW309 filter, I have to say that 5 sec is not enough. Here, for displayed power only, more smooting are maybe necessary (10 or 15 sec, and I guest that maybe some triathlete would like 30 sec since some of them take this option with the PT computer). So the ideal would be to be able to chose between the type of smooting (none, 5sec, 15sec or 30sec), like the PT computer. Otherwise a 10 or 15 sec averaging would be already more usefull than the "actual" (beta!) 5sec.