New powermeter

Hi all,

Last week I bought my first power meter for my outdoor bike. Until now I used the Heart Rate Derived option for outdoor rides. My indoor trainer already had a power meter.

I am just wondering if i should expect major changes in my signature now I am switching to a PM to for my outdoor rides. Anyone any ideas?

Not really, as long as your outdoor PM is in line with your indoor trainer. Depending on the precision of either, you should not see a significant change and eventually, using both will even things out anyway.

UNLESS, either of your PM sources has a significant error, or if you have a left only outdoor PM and a significant L/R imbalance. A left only PM, just doubles the power from one leg and if you have a L/R imbalance of 45/55 or 55/45, that would matter.

Most PM’s have an app with a scaling factor, so you should then enter a corresponding correction number, usually a percentage.

The trick or the problem here, is that if you do get significant differences in output, you would need to figure out if it is your trainer, your outdoor PM, or a L/R imbalance.

I wouldn’t bother about ~5 Watts differences, because PM’s have between 1% and 2% precision margins anyway.

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You may find some increase as a lot of people can put out more power for longer outdoors… plenty of reasons including better cooling, different mechanics (bike moves under you), different position (eg climbing shifts centre of mass and angles, so some put out more power up hill), different psychology (eg when powering up a real hill vs a virtual one indoors)

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Thanks guys! Good points for me to look into.
Initially I was only thinking about differences in Xert signature numbers but like @wescaine stated the position on the outdoor bike is quite different probably resulting in a different power graph. E.g. when I go outside I will not be continiously pedalling like I do when I am on the trainer. I should be able to see that back in the graph (and perhaps numbers).

@Cyclopaat I did got an app provided with the new PM. Will definitly take a closer look if I can notice any power imbalance in my legs and see if needs to be corrected (in the app that is, the legs are lost already :slight_smile:).

What Wes pointed out, is indeed something you will have to figure out for yourself. For me, it doesn’t really matter whether I’m in- or outdoors, looking at power numbers.

It does matter regarding lots of other dynamics and environmental circumstances, but tbh, I have given up on riding 3 - 4+ hours indoors, so as long as I stay under 3 - and usually, my sessions are 1,5 - 2 hours - I’m fine.

My Neo has some sway, so other than not cornering, I’m also not that static on the bike as on more rigid trainers.

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Can you feedback after trying them Johan? I’m currently awaiting the Assioma Duo’s to arrive and like you wondering how going from heart rate derived vs power will alter things - my outside rides based on HR always show as harder than my indoor ones, while I suspect I do push harder outside, i also suffer from a high heart rate during physical activity (but low resting heart rate, it’s not unusual for me to have an average of 165 outside, max 185 but resting is around 60).

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The Assioma Duo’s are awesome - the only flaw is that they are a little hard to clip into, as they turn around easy. I guess no real dead-center balance point, or whatever the physics behind that is :sunglasses:

HR derived power will - at least for now / a while - be a best guess thing. Having a real power meter is the only way, but not everyone can afford that.

I would think that since your indoor rides are based on real power and your outdoor rides are best guesses, it may well be that you actually push harder at a lower HR. Indoors, with the extra burden of cooling problems and other stuff, your HR will probably be higher. I know mine is…

I can’t beat 185, as I’m too old for that shit, but 174, indoors, yes - however, my resting HR is 48 and when I sleep, it drops below 40. I’ve been woken up in the middle of the night whilst in a hospital, just to check if I was not going into a cardiac arrest :joy:

On the 30 mile I did in 2018 the peak we saw on my HRM was 192. I reckon I can still pass 200 if I was willing to take myself to the point of throwing up! :joy:

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Your PP may jump up significantly. Most riders can max out a sprint more effectively on the road.

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Will do Donna! This afternoon was the maiden ride with the new PM. Didn’t went well because calibration wasn’t done properly. Only at the end of the ride I decided to calibrate again and then it worked just fine. But the power registration for the ride was screwed already by then so I stripped the power from the ride and uploaded to Xert without power.
This weekend I will give it a retry. Will let you know the outcome. I am also very curious how my real power is compared with the calculated power from heart rate derived rides. Keep you posted!

Thanks, will make sure I keep an eye out, joys of having small feet means feet shouldn’t interfere too much and my look pedals like to spin too so nothing new for me.

Wanted pedals not crank for ease of changing with bikes, was going to go for Garmin V3 originally but read about too many issues with them and having had a bad experience with their CS team over one of their HRM’s I’m keen not to deal with them again.

Re Assioma’s rechargeable batteries: you’ll be looking for something else long before they eventually do wear out. I will probably be dead before they do :joy:

Each charge really last for 50 - 60 hours, which, depending on how often you use them, means one recharge every 4 to 5 weeks, less for most, certainly if you mix training with your indoor smart trainer.

The 4 (!) coin cells needed for the Vector 3 pedals are like 15-20 Euros each time and I had to change them every two weeks. Also because my Edge would inform me that they were running out, a warning which apparently came too early and was kinda (like always with Garmin) fixed in a SW update.

Plus, the battery compartment is poorly designed and you have to side flip the bike to get them out and fiddle to get the new ones back in. PowerTap is a lot smarter as far as that goes…

This is from Favero’s website, in case you didn’t look for it already…

B010 What battery does Assioma use and how long does it last?
Assioma uses a rechargeable lithium-polymer battery; before being integrated into the sensor, each battery is individually tested in house by Favero Electronics to ensure maximum durability and performance. The declared battery life is 50 hours. The battery of Assioma has been designed for professional long lasting applications: after 500 complete recharges, i.e. from completely discharged to fully charged, its capacity is reduced by only 20%. Note that 500 recharges are more than 25,000 hours of use! Plus, you can charge Assioma with the included charger, but also through any USB output or a common power bank.

B020 Why choose a rechargeable battery?
The advantages of having an integrated rechargeable battery are many:
• No risk of failure caused by water or moisture infiltration: in fact, there are no openable battery compartments to worry about or sealing gaskets that over time may no longer guarantee the initial waterproofing.
• Zero problems of non-contact between the battery and the electrical circuit terminals. The battery is directly welded to the circuit, and then resinated; so there cannot be any unwanted power interruptions. Whereas, this sort of issues is typical of replaceable battery systems, due to the oxidation or the movement of the electrical contacts.
• The battery charge level is monitored much more clearly and reliably than a replaceable battery; and with the Favero Assioma App you can check it at any time.
• “Low battery" is signalled punctually, ensuring you have enough time left (8 hours) to finish your race or training without problems.
• No worries to replace, buy and dispose of the batteries – for the benefit of your wallet and the environment.

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Ok, just did my first decent ride with my new PM (Stages 105 R7000, left pedal only).
First thing I noticed was it often needs calibration. Maybe because the pedal is new and needs to settle in a bit, but during this first ride I did a calibration at the start and halfway when I felt power was dropping and not inline with real power anymore.

After comparing the ride details from the ride with the PM and an earlier ride without PM (heart rate derived) I noticed that the heart rate derived numbers aren’t that far off.
Ride details with PM:

Ride details same route without PM (heart rate derived):

What the PM obviously does better is determin the Focus type of the ride.
With heart rate derived rates this is often Triathlete or TimeTrial type, while the PM recognises the power spikes and changes Focus type accordingly. In this case with PM it is Climber for the same ride.

When using an PM for outside rides is becomes clear that outside rides have such a different Power profile than Trainer rides. With trainer rides the target power can be set and the aim is just to follow that target. No big deal, just push the pedals around. With outside rides the aim an specific target power and it is really difficult to achieve the average target power. Especially when you live in in a urban area like I do where you do have traffic lights, grandma’s suddenly crossing the roads, cars that block the road, etc.

All and all I am happy after my first ride and am curious what the PM will bring me also in use with Xert.

Gr Johan B


Thanks for sharing.

Curious to see how your first outdoor breakthrough looks when you do it. Good to check your outdoor peak power (I.e. do some sprints while fresh but warmed up) and also a normal breakthrough e.g. really hammer up a long enough hill and get out of the saddle for the last bit :slight_smile:

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I was actually surprised when i took a look at the power curve of this ride how close it was to the power curve for whole 2020:

I never pushed anywhere during this ride (it was supposed to be easy endurance) but if I had done so I probably would have seen a BT.
So next time I will indeed put some some power on the pedals in these uphill sprints and see what happens :-).

That is not very likely - you do not get to 700 Watts if you are not at least trying…

This is what not pushing looks like :joy:


I came out of the saddle every now and then but I never pushed like I do and have done on my trainer (where I fall of my bike after the race is done).
So i guess it comes all down to the exact definition of “pushing” :slight_smile:

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700 Watts is pushing :stuck_out_tongue_winking_eye:

Then there might be something fishy going on with the new PM. I never pushed the whole ride. Maybe it just picked up a power spike when standing on the pedals, I dont know. But i haven’t sprinted up to 700 Watts in this ride for sure. My PP is around 900 and I know what that feels like :slight_smile:.

What does the whole ride look like? If you see spikes, while you were not sprinting up a bridge, then something is wrong.

I don’t know that particular Stages - I had a 1st gen and I only calibrated it before I left, not even every ride and I have never had to do it mid-ride…