AeroPod, PowerPod and Newton

This evening I got out on a ride which included the Bear Road hill. I was a bit slower this time, but the result is essentially the same as previously. I have attached two ibr files, one for the whole ride and one for the Bear Road section only (which occurs at 24 km in the ride). Interestingly I wa...

I was wondering that as the PP can detect ‘side to side’ and ‘front to back motion’, could the acceleration associated with this movement be easily subtracted from the acceleration value used to calculate power and slope?

I've just been out for a quick test ride which involved riding up a nearby hill (elevation gain of 39 m over 600 m, 6.5%) 5 times. The hill has a fairly constant gradient and I tried to ride it at the same speed (14.5 km/h) the entire way up for each effort. 1. Seated (14.6 km/h 258 W based on gradi...

John Thanks for the PowerStroke key, very generous of you, I will download it and will definitely post the results. I was thinking that the extra acceleration could be taken into account if it can be differentiated, otherwise the calculated power is presumably based on the total acceleration and the...

So I have just been out and I did a couple of 'tests' and to be honest the results aren't very encouraging. The first was a short 500 m hill with an average gradient of 5.2%. I rode it four times, seated, standing, seated and standing, each time I tried to ride it at a similar speed, this occurred a...

John I think the Google Earth numbers are wrong for that section. Based on Ordnance Survey elevation data for that section noted above the elevation gain is ~23 m (from 96 m to 119 m), this also corresponds with the PP barometer, my Garmin barometer and my perception riding it! This section is ~200 ...

The problem isn't so much the inaccuracy, although the 35% discrepancy in the 400 m section posted above isn't exactly great! The problem is consistency and it seems as though the reported value is more and more inaccurate as the slope increases and gravity is the dominant factor (~90%). Then the ac...

John, I was out today riding and I was thinking about this problem. I work with accelerometers to measure ground vibration, so have a basic understanding of them. We use triaxial accelerometers with a manufactures sensitivity of 1,000 mV/g, however we do get these calibrated regularly to ensure we g...

Hmm, I am still not convinced! You are using the reported slope of 13.8% to calculate my power for that section, if that is the actual gradient then my power would rightly be ~500 W. However over that distance of ~400 m I have only ascended ~40 m, going from 30 m to 70 m above sea level, see the ima...

Again thanks for taking the time for a detailed reply I now appreciate that the power value is a function of total acceleration (and speed etc.) only, and not the slope value itself. However there still seems to be an issue for me here, and that is that the reported power for me uphill appears to be...

I'm quite possibly missing the point!

My understanding is that the reported power value is partially a factor of the slope value, which on steep hills when traveling slowly, is not as accurate as it usually would be on less steep hills travelling faster?

John thanks for your detailed response, I think I understand what you are describing, but I have to say that I find that a bit frustrating, if unavoidable and I'm not convinced I am getting solid power measurments; basically the steeper the hill the less accurate the reading. Is there no way to fact...

I am just looking back at other ride files and am seeing this issue crop up quite often. basically the PP is significantly out in the gradient used to calculate power. I have attached another ride file with several hill efforts. 1. Around 15 km for 1 km, the PP average gradient says 13.2% but the ac...

I posted the other day about how I felt the PP was overestimating my power output uphill due to a tail wind. Following positing it seemed that actually the numbers were correct, however I still was a bit surprised I was able to ride at ~450 W for 5-minutes, quite a bit higher than I thought I was ca...

I have saved the effort only ibr file attached to this post.

It would be really useful if I could add the power to the first 50/60 s, is that possible?

Edit:

Scrap that, just found the repair for missing cadence feature, great stuff!

Excellent! I rode a similar hill yesterday and got similar numbers, albeit with no particular wind of note, which gives me confidence! Thanks for your replies. Edit: Actually the first 50 seconds of his effort the power reading was 0 W, which was a bit annoying, i assumed the PP was not picking up t...

Thanks for your reply, maybe I am better than I think!

So does riding at 15 mph with a 15 mph tailwind mean that as my relative wind speed is 0 mph the only opposing forces are gravity and friction? Would there not be a supporting force too, or if there is would that be negligible?

Would the Powerpod overestimate watts when riding uphill with a tailwind? I’m pretty sure my Powerpod is correctly calibrated, at least more or less, but I do notice that when riding uphill with a tailwind watts shown are higher than if there was no wind or a headwind and also higher than I would ex...

I too regularly notice downhill watts being vastly over estimated. Often I will see the PP saying 300/350+ W when riding relatively easy downhill, and based on exertion and HR I would expect to see considerably less than 200 W. My position is always the same too, certainly no different than how it v...

1) We don't disclose how we implement our technology 2) I appreciate your conservatism. It's up to you whether or not you update FW; just be aware that, if you don't, you cannot get the potential benefits of doing so 3) Your ride file does not show evidence of excessive road vibration; your watts a...

The FW update adjusts the rough-road detection algorithm so that it does not over-react when TT bikes are riding on rough roads. How does the PP know that you are riding a TT bike as opposed to any other bike? Would the PP not over-react when other bikes on rough ground too? Generally I don’t like ...

Time to update your PP firmware! • Corrects an issue with TT bikes where reported watts might be too high • Corrects an issue with Fat Bikes where rolling resistance might be too low You can access this firmware through the Isaac command "Device/Check Online for Firmware Update..." What d...

Ok, thanks for the reply, good to know.

How much do I need to 'worry' about this value? Having had the PowerPod for the past few weeks I have been checking the calibration post ride, particularity after out & back TTs. The wind scaling value seems pretty consistent and I am happy with that (~1.4), however the Riding Tilt (%) value cha...

I have a profile that has been set using the check calibration analysis following an out and back ride with a set CdA value (0.29, TT Bike position). If I now want to 'tweak' the profiles CdA from 0.29 to 0.27, as I think it may have been set too high during the out and back ride, should I hold the ...

OK, that makes sense then, thanks.

I have attached some screenshots to this now. 1. this is the ride file (cant add this screenshot, too many images) 2. this is the edit profile screen with no profiles 3. this is the edit profile screen after extracting the ride file from the ride 4. this is the switch profile screen showing the Watt...

This is the orginal ride file in question.

I just went to apply, post ride, a different profile based on a 10 km out and back ride I did today, to a ride I did on Saturday. This had the effect of reducing the average watts by ~20 W, from ~215 to ~195 W. Prior to applying the new profile I extracted the original profile from the Saturday ride...

Thanks for your reply. Yes you are right the profiles for the two rides are the same as I did today's ride without changing anything, i.e. the same profile as yesterdays ride. I was looking at using the 'Check Calibration' tool on today's out and back ride which suggests the following changes: Aero ...