AeroPod, PowerPod and Newton

I've been on I think four rides now since I got the PowerPod this week. After initial calibration things seemed mostly OK, but I haven't gotten one ride without serious anomalies since.

I am using the K-edge mount, off to the rider's left of the stem to stay clear of cables, and pretty flat as I use a heads-up display and prefer the computer about level with the ground. I've got the powerpod rocked forward as far as it will go, and screwed down tight using a screwdriver on the GoPro screw. After each ride I've done an "analyze ride" in Isaac and sent the updates to the PowerPod. I've also set my weight, bike weight, tire size, etc.

I continue to see, at some point during each ride: power clearly too high on flats, power clearly too low (like, 0W at a 50-100W effort, which climbs to 13W when I crank the pedals at about a 200W effort) on descents, riding alone being misidentified as drafting, and so on. The last two rides I haven't removed the PowerPod from the mount, but have brought a laptop out to the bike in the garage to ensure I'm not re-mounting the pod at a different tilt.

I do have a DFPM I can put on this bike for calibration, but it requires swapping bottom bracket, crankset, and chain over from another bike, so unless there's some great assurance that this would help, I would prefer to avoid it. Ideally I'd like to be able to use this thing between a couple of bikes, but now I fear that ever removing it from the mount will cause too great an upset.

Does anyone have suggestions what I can do to get consistent ride power that matches what I know my various power levels feel like from riding with a DFPM? I'd really like to keep the PowerPod, as there isn't a great way to put a DFPM on either of the two bikes I want the PowerPod on, but at this point it's not clear to me that the PowerPod is providing me any more or better information than a heart rate monitor.

I've attached my last two ride files. As I said the powerpod is cranked down as tight as it can safely go, same with the mount on the handlebars, and I have not removed it between these two rides. They have already been analyzed and adjusted in Isaac.

Your first ride takes 8 minutes for the auto calibration to click-in. However, the wind calibration is incorrect; I'm not sure how this happened.

The second ride is much better but it looks like you used the Check Calibration feature to get it right. The original ride file shows a consistent tail wind, too.

The attached profile, when loaded in to your PowerPod, should do the trick.

With the correct profile I don't see any of the issues you describe.

Thanks, any pointers on how you created that profile? I've got a one-hour recovery ride today, I'll give it a try.

The bike does have Shimano Sora shifters with the cables coming out of the sides of the shifter bodies, but that's why I placed the mount off to the left, the cables are well out of the way of airflow to the PowerPod, as far as I can tell. Maybe they're still causing some turbulence or something?

I used the Analyze/Check Calibration feature of Isaac.

I don't see any unusual wind turbulence in your ride file

Today's ride was a little better -- power on the last downhill was reasonable, I was cranking pretty hard.

However, the initial almost-flat (about miles 1 through 3) it was telling me I was in zone 2 or so even when I was just soft-pedaling enough to move the cranks while coasting. When I went to check calibration after the ride it asked if I had been drafting, as it thought I was drafting 4.8% of the ride -- I definitely was not.

Any thoughts?

For the first 8 minutes of any ride, the PP will recalibrate itself.

You reattached the PP after loading the new profile, so that is why you don't see gobs of power for the first 8 minutes.

You had a tail wind on the out portion of your ride and a head wind on the way back.

It looks like everything is fine.

The PowerPod did not move off the bike the last three rides. I did see much more power than expected at the beginning of the ride, I was expecting little, especially around 2.7 miles or so, because I was soft-pedaling as a test and it showed me 200W.

If this is expected performance then I guess I'm done.

The new profile I loaded in to your PowerPod had a "tilt" factor from the previous ride. That's why the first 8 minutes were off.

If you're not removing PP between rides then you should be OK going forward.

I set up the new Wahoo sensor this morning (uses magnets, had ordered with intent of using PowerStroke), and got the speed calibrated.

It seemed to work much better, power values I saw while riding made more sense.

I checked the old sensor and noticed a 3mm difference in wheel size. It may have been calibrated with the old tires or on a different bike with very similar wheel size. Could that be the cause of the odd results from my prior rides?

I don't think a 3 mm difference would have a material effect on things.

Post a ride file and I will check things.

Unfortunately the magnet position wasn't quite right at first so I didn't get a complete out and back ride for calibration checking but here it is.

You show a constant headwind in this 8 mile ride file. Is this correct? It does look like your earlier 14 mile ride file was in the same place, and that this file had a head wind in the same place, too.

I didn't see this until now and it's been a while, but I think yes typically the wind is the same here day to day.

OK, then I think all is well...