Ahem TiRed…

Instead of rattling around the TT thread I thought I put this here.

Calibration – So I did my calibration ride, which apart from 4 stops at lights and a turning truck, went fine.

But on completion I find myself riding around in the small ring at an RPE of about 3, 18mph pulling 350w on my garmin which is displaying power with 3 second smoothing. I’ve returned, and strava shows an average weighted power of 170w over 5m (94w average actual due to the calibration phase) which I’d actually say is about right.

It seems to display high watts – why/can I calibrate again?

Not happy – I bought this on its merit as a portable device, but I’ve found that the slighest movement affects its measurement. As I’m using a Garmin out front mount with action cam mount for it, it doesn’t have the stop to position the powerpod. This effectively means everytime I change it from bike to bike on the basis its position would be minutely different from the original calibration position, render it invalid meaning I’d have to calibrate each an every time I move it. So its not really portable at all, is it?

Not heard of one of these so I googled and found the DC rainmaker review. Any help?
dc rainmaker review

I’ve just read it again, and a different review elsewhere.

Basically, chaning it from bike to bike means calibrating again. I’m not too peeved about when it goes to the TT bike as I’d do that in the warm up out an back from a village hall or laps of Hillingdon.

But if I’ve moved it from there to the road bike and just want to get the bike out of the shed for a quick spin/training ride I can’t just switch it on an go. I have to do a calibration ride first before I can get on with things 😐

Edit, unless I revert to the original powerpod mount on the road bike, then the powerpod is always in the same position for that, and I just have to recalibrate before my TT’s. Thats easier

I understand how these things can measure wind and gradient, but how do they account for changes in body position?

Edit, unless I revert to the original powerpod mount on the road bike, then the powerpod is always in the same position for that, and I just have to recalibrate before my TT’s. Thats easier

Nope, doesn’t work. It’d be in the way of my cables and I can’t move it far enough outward as my bars are aero profile.

FFS

Hmmm and now having read DC rainmakers review means I can leave it to “heal” its self.

Calibrated for the TT bike I might then move it to the road bike. According to DC rainmaker it’d start incorrect then over 10 mins or so correct its algorithms.

Hmm dunno…

I think mrblobby is using one of TiReds powerpods at the moment too so he may also be able to help.

Never got around to it unfortunately.

Why not mark a position on the Powerpod and one on the out front bracket? Then the up down orientation will always be the same.
All sell be the Powerpod cheap and forget about it 🙂

Yes, definitely calibrate it again. Ideally do an out and back ride of about 15-20 minutesalong the same stretch of road with no stopping etc.

For swapping between bikes you’re best off keeping as much constant as possible. Separate speed/cadence sensors etc and different bike profiles. Running it on a mount without a hard stop point is always going to lead to some initial inaccuracies during swapping about until it self heals.

Personally I’d get a mount which had the stop and get the initial readings as close as possible on the road bike and get the proper tribar mount for the TT bike.

The numbers might still be a touch out after moving between bikes but they’ll be a lot closer, then the self heal thing can work its magic.

Oh, and make sure your not using smoothing on the Powerpod profile as well as smoothing on the Garmin. Too much smoothing makes things a bit funky numbers wise.

Ive got seperate speed sensors, so its realistic to move it across bikes without re calibration if i can get the power pod aligned the same?

Ive worked out – i can attach the powerpod with the words horizontal measured by sprit level and mark the mount an the pod. Once calibrated again on the road bike, i can mark it and the mount, swap it to the TT, align with spirit level and mark rhe TT mount opposite the pod. Then the Healing will help during the TT warm up…. maybe.

A few comments:
1) How did you fasten it to the mount, and which mount did you use?
I use the bolt rather than the knurled knob, to secure a tighter fit

2) How did you set it up with Isaac? TT position (CdA will be 0.25, glued tubulars and 23c tyres). This sets the Crr and CdA to the ballpark figures before you do a calibration ride.

3) I presume it paired successfully with the ONLY speed sensor on the bike (solid green light)?

4) Watch the out and back, I’ve found coming back can be longer, so pick a ride that has redundancy in it to keep going.

I’m using a Garmin out front mount with action cam mount for it, it doesn’t have the stop to position the powerpod

Most mounts have a ridge which means you should rotate the pod FORWARD until it locks against the mount. Then cinch it down with the bolt. This works fine on all my mounts except the Giant Propel – which has deeper grooves. For the Propel, I insert a 2 mm allen key into the gap and rotate the pod against that instead.

If the Powerpod is mounted firmly against the stop and pairs with the correct sensor, the tilt is loaded from the correct stored profile and there is no recalibration. If you are riding along, and you hit a bump and the pod moves, then it will recalibrate.

It is VERY sensitive to tilt, hence the need to keep it firmly attached and rotated forward (if it thinks you are climbing a hill, the gravity watts will be calculated for climbing). The sensitivity is to 0.1 degrees I believe! Don’t bother using a spirit level, you will not get the accuracy of alignment – not even close. Use the mount properly. On my handlebars (I have three bikes with the stock mount which is rotated forwards slightly, on the TT bike I push the pod fully back instead, and don’t remove it. The logo is about level on every bike.

Once calibrated, the tilt recalibration is dynamic, it will come back to the correct readings regardless of where it starts from after 8 minutes, but using a fixed mounting position is much smarter, along with it’s own sensor.

EDIT: as for Garmin, I use instant power on the garmin but dynamic smoothing on the Powerpod (default). The engineers at Velocomp have done their sums on signal processing, the real-time response is very good indeed. This includes coasting and soft pedaling, where you will see watts go to zero, even without cadence meters

I understand how these things can measure wind and gradient, but how do they account for changes in body position?

It doesn’t, and in fact studies by Velocomp showed that it doesn’t really need to. You’ll find that most riders spend most of their time in one position and swap a little (hoods onto drops, for example). The change in this CdA is about 5%. Tucking into a TT with arms resting on the bars would be a bigger issue, which is why there is a separate setting for TT bikes.

I have wggle / lifeline dual garnin/action cam mounts – no stop.

But you are saying it will recalcalcute alignment should it be wrong (the Healing DC Rainmaker talks of)?

I did use the knurked knob as ive kept the bolt for the TT bike. There was only one speed sensor – the one in the same bike when in paired them.

As a slight twist ive been reading about Garmin Sensor speed vs Garmin Gps speed which is slower. The ride seemed faster than it felt also, and I wondered if rhe speed centre had screwed rhe Watts on the Powepod. The speed sensor had no calibration or setup somin theory cant be wrong.

Re your edit inhave powerpod smoothing off, garmin at 3 secs

I have wiggle / lifeline dual garnin/action cam mounts – no stop.

Try my allen key trick, 2 mm key, slid inside the gap in the mount, push the pod forward and lock it down, then remove the allen key. I do it on the Propel all the time. Watts are consistent from the off.

I once ran 600 Watts for a club 25TT because the combo speed/cadence sensor was recording double. I’ve had no issues with the front hub mounted Garmin speed only sensors. I use them exclusively now for all except the Zwift (BLE Wahoo to ipad).

The change in this CdA is about 5%.

This will make a significant difference. It could take mine of trying to boost threshold by >10 watts.

What do you do if you don’t want to do all your training in race kit? Do you keep a separate calibration it for your rain jacket?

Sorry, bit unclear from your post but are you using a standalone speed sensor and if so is it on the front or rear wheel? Front is better as the signal is less likely to drop out leaving the Powerpod dependent on the much less accurate GPS speed reading.

Garmin speed sensor, standalone, different one on each bike.

Both mounts are rhe same so – thanks TiRed – ill try the allen key trick to get consistent spacing when swapping the pod, and re calibrate.

This will make a significant difference

Not to a weighted mean of position x time spent in position over a ride. Mine is calibrated for drops, as I spend much of my time there, particularly when the power is needed. I use mine as a target for training efforts. So if I want to ride at a reported 230 watts target, that’s what I do, when it’s reporting 190 then I push on, exactly as did with my Stages. It is accurate enough for these purposes.

And no, I don’t worry about my rain jacket. I’m not pushing out 5 W/kg in the rain 😉

Have you tried posting on the Newton/PP support forum? John Hamman (sp?) is usually very responsive. Sorry if this has been said already IHRATS 😉

For my part I use a K-Edge combo mount and it’s solid as a rock. Get it nice and level (the PP) and it settles down nicely. I swap infrequently between two bikes and have two profiles in Isaac it sometimes needs to recalibrate but settles down soon enough. For instance I swapped it from one bike to a completely different (albeit similar) one and within the promised 8 minutes it was reporting sensibly again. I’ll tweak the profile in due course.

It does all seem a bit sixth form electronics project when you think it’s not working but it does work I’m convinced! Good luck 😉

Come along early tonight Kryton. I’ll have my laptop and you can ride a calibration out and back on Hillingdon circuit. When I rode mine, I didn’t reverse direction, just kept going. I changed the angle of the arms and the powerpod adjusted to the new tilt this morning.

But I still need 320 Watts/lap to break 23:00. Looks cold and windy 😕

I’ll be leaving from Henley at 4:30 so should be there 5.30 – I had that exact strategy in mind. I already have the pod mounted and setup for calibration, just need to connect it & the speed sensor to my bikes profile on the Garmin and I’m good to go.

I calibrated it on the road bike the other day – rode out to the country and found a long enough uninterrupted road to get out & back with out stopping. It reads the downhill as power, I’d be interested to ride one of my typical training rides and see if it calculates coasting to adjust the overall ride power accordingly.

Yes it looks cold and I brought m,y 50’s so will be holding on tight – it’ll be a fast dash from the building to the start lol. See you there!

Something definately wrong here. A 3 hour moderate pace ride in Saturday measured in at 450 tss, which of course cant be he case as that would reflect 3 hours at 125% ftp.

Ive checked all the settings, rider weight, cda etc and they are all correct so ive written to the technical helpdesk for advice.

It will be your wind and aero scaling. CdA, Crr are pretty well-defined for any profile. Wind scaling is used to ensure that a circular ride with no change in overall wind has zero average. Look at check calibration in Isaac for such a ride.

So if i select a ride and run check calibration will ir download the revised content to the device?

It creates a new profile called “tweaked from…”. You can then send this to the powerpod either in the check calibration window, or via the device menu.

@ Tired;

Well, velocomp examined my file and strangely the CRR is 0.085 where they expect it to be 0.052, which elevates my FTP then watts.

I’ll be making the manual adjustment for both bike profiles and seeing how it goes…

Edit – can you explain what & why you did the calibration check you spoke of in the TT thread today?