Power Meter Confusion - In and out of the saddle readings

Equipment
#1

I just purchased a Favero Assioma Duo power meter pedals and the results have been confusing. I mostly bought these for indoor training on a spin bike to get me through the winter months.

In the saddle the results are pretty much what I would expect. 60 - 70 watts - easy spinning, ~150 watts at a tempo pace, I’m feeling it at 200 watts, and 350 - 400 watts if I push it. However, once I go out of the saddle, where I would expect to be able to really push down some watts, my power drops. My cadence drops some, but as I really put my body weight into the pedals (I’m a heavy rider at 235 pounds), the watts don’t go above 200. I would have expected to be able to go beyond my max in the saddle, especially given my weight that I would think I’m pushing into the pedals. Additionally, my hands are pretty light on the bars when I’m out of the saddle, which I think is ok form so my weight really has no where to go, but the pedals.

Are others possibly experiencing something like this? I have calibrated (zero offset) the pedals many times. I will contact tech support at Favero, but they have already explained to me how overwhelmed they are right now so their response times are very poor.

#2

I’ve had my assioma a year and never noticed this. Do you have some ride files we can check out or a screenshot? Maybe highlight where the issue is or a little arrow pointed at the trouble spot?

#3

When you stand up could you occasionally be touching the power of with your cleat ? I have the older Favero pedals and I had to file down the outside of the cleat to stop that happening and causing power to fall.

#4

Thanks for the responses. I can provide a ride file as well if you think it would help, but I thought I might take a quick video to show you what I’m seeing. Basically, in this video you’ll see me going along at 100 watts in the saddle, then I increase to 200 watts in the saddle. Then I jump out of the saddle and use all my body weight (240 pounds) into the pedals while keeping my cadence the same or higher. You’ll notice my heart rate spikes up pretty good because I’m pushing it, but the resulting power does almost nothing. It seems to go up only a slight bit and then actually drops below 200 watts. I would think with the additional effort and pressure that feels like I’m putting into the pedals, the power would go up, but it is actually much easier to get to 300 and 400 watts in the saddle. It just doesn’t make sense to me.

#5

On a geared bike many people would shift down a cog or two when standing and up a cog or two when sitting to compensate for the cadence changes (if trying to keep power constant.) When you stand up your cadence looks to be dropping a little bit (if I interpreted the numbers correctly) and resistance is unchanged so your power will drop. I think if you tighten the resistance knob before standing you won’t notice the power drop as much.

Personally, my perception of effort and cadence change between seated and standing positions. I can be spinning along at 100rpm seated, stand, and think my cadence is higher standing but it is actually 10-15rpm lower.

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#6

Great points Craig and I couldn’t agree more. I’ve noticed the exact same phenomenon you mentioned where my cadence will drop when standing.

However, I’ve seen so many times on YouTube and elsewhere when someone wants to really increase their power, they jump out of the saddle. I wish we didn’t have COVID going on because I would go try a more high-end spin bike at work and see what the results are. I want to say when I took spin classes that getting out of the saddle would increase my wattage at least 100 watts, but maybe I’m wrong. It just really feels like 240 pounds of my weight pounding down on the pedals with a heart rate of 175 and a cadence of 85 would yield greater than 190 - 200 watts.

#7

Power on the bike is force time pedalling speed, and usually calculated over a full rotation. When your cadence slows, your power will drop. Putting your whole weight on the pedals doesn’t change that, especially as you can only put your weight on it for a half-turn of the pedals, and then its back to pedalling speed, how quickly you can shift your weight to the other leg.

The other thing is the resistance - at low resistance, you cannot create high torque. Think of it as being on a bike in a really low gear. If you want to really stop down on the pedals, crank the resistance up as much as possible.

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#8

I use crank-based power rather than pedal-based, but I don’t think it’s an equipment malfunction; I suspect that it’s probably a legit power reading. When I’m climbing outdoors, I stay in the saddle 99% of the time because it’s the most efficient way to deliver power to the pedals. Standing increases my perceived effort, but my watts don’t increase when I stand.

So when do I stand? 1) When I need a quick break (again, not that the effort goes down when I stand, but standing probably engages slightly different muscles), and 2) when the gradient of the climb outruns my gearing (standing allows me to still turn over the pedals when my gear combo is too big, e.g. on >15% pitches).

Not a Favero user, but just wanted to offer the perspective that I experience essentially the same thing and suspect it’s not stemming from a problem with the power meter.

#9

Thanks again for the replies. I completely understand what everyone is saying. However, now let me throw out something I just learned that I think might make things more confusing.

My main bike is an M5 CHR recumbent bike. It is a very fast bike. I put the power meter pedals on it, calibrated it as the instructions state, and took it out for a quick ride and I was shocked. 200 watts felt very different from 200 watts on the spin bike. 200 watts on the spin bike was much harder. If I wanted to surge out 600 or 700 watts on the recumbent, I could. I don’t see that would be attainable on the spin bike, regardless of the resistance I had.

I would have expected these results to almost be identical and they are not. That is, 200 watts on the spin bike should provide the same level of exertion (heart rate) as 200 watts on the recumbent. Is my thinking wrong? As you move these pedals to different bikes are 200 watts easier on some than others?

#10

You’ll be using muscle groups in a completely different directions on a recumbent as to an upright bike, its only natural that the effort to achieve 200w will be different. Your muscles will work easier in one direction there’s also a large number of external factors which will see different results from the indoor to the external environment.

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#11

One watt is just one watt especially measured by the same power meter! Recumbent bike is a kind of cycling equipment with back support. That means you could generate a larger force than your body weight. Therefore, riding on recumbent bike with same power, you will usually use lower cadence but higher torque, then your heart rate will be lower relatively comparing with riding on spin bike. You will feel easier to get to the target watts on recumbent bike for sure, however, one watt is just one watt, you drive more fast-twitch muscle with higher torque, your glycogen consumed faster.

#12

Thanks Brad. I don’t know how much experience you have with recumbents, but what you are saying is the opposite of common thoughts about recumbents. Recumbents are typically faster on the flats and descents because of the more aero profile than uprights. However, on the hills uprights are typically faster because people say that those on uprights can put their full body weight into the pedals whereas those on recumbents cannot. I can say based on experience on group rides this is almost exclusively true. I wouldn’t consider myself a Group A rider, but I can outpace most of them on my recumbent until we hit the hills. Then the uprights will start to pull away.

#13

Going back to the original post - and as Splash pointed out - if you maintain the resistance unchanged then your power output will be solely a function of cadence. Thus, assuming you are not increasing the resistance, when you drop the cadence as you stand your power output will drop. You may still see a rise in HR due to the posture change (unless cadence and power output are dropping significantly) and you may also perceive it to be harder.

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#14

He didn’t mention anything about that. I seem to be reading a reply to a different post, because it’s not flowing correctly, in terms of context and making sense. :slight_smile:

Yep, looking at the video, its cadence. You were at 85/86 rpm, Z5 HR. You stood up and went to 81rpm, with the same resistance with rpm spikes where the power matched seated and event went above. So, naturally, the power will drop with a lower cadence. HR went to Z6, so higher RPE.

Edit: spelling.

2 Likes
#15

Thanks Matt. Well put. I guess for me now is that the bottom line is the power meters feel like the wattage is just overall too low. I’ve done a static weight test and they measure a little low on power, but not so much to explain what I’m seeing.

I think I might have to risk it one time during this pandemic, put on my hazmat suit, and go ride on some spin bikes and exercise bikes at the gym that reflect power. If the results are all similar then I’ll know I’m just far more out of shape than I originally thought (entirely possible) :slight_smile:

#16

  • Fair warning, but unless you are on the Stages spin bikes, I’d not plan on using them as the “measuring stick” to check your power meters. Those bikes, especially in those environments are well known to have questionable power reporting.

  • Unless you use another quality smart trainer or different style power meter to compare, I doubt you will prove anything from your proposed test.

Is this all boiling down to you not trusting the pedals since they give you lower power than you think you are producing?

To be honest, I’d trust them above anything else you have mentioned.

2 Likes
#17

Great point and I’m aware. I’m looking for “ball park” estimates because I don’t feel the power meter is providing accurate results on my spin bike. The results seem pretty low to me, but I might be wrong or just woefully out of shape. :slight_smile: I don’t know. To keep 200 watts on the spin bike would be very difficult for me over anything beyond maybe 2 minutes.

Conversely, I can take the same power meter pedals, calibrate them, and put them on my M5 recumbent and go ride outdoors. 200 watts isn’t only sustainable, but it is done with such less effort it seems like I could hold it for hours. Those results almost seem too high.

Ultimately, I don’t know what is happening, but I expected there to be a difference between 200 watts on a spin bike vs. a recumbent bike, but not to this degree. This combined with other anomalies makes me feel something might be wrong with the power meter.

The irony is I bought the power meter to test things and to help with workouts, but I’m instead spending time testing the power meter. :slight_smile: Oh well, thanks again for the input, and I’ll see where this goes.

#18

Not sure it was mentioned, but have you made sure you have the crank length setting correct in the pedals, to match your spin bike?

And to double check, are the spin bike and your recumbent the same exact crank length? If not, you need to swap the length setting in the app (that pushes to the pedals) to get correct power info.

Ignoring the potential pedal data, you have 2 massive differences in your testing:

  1. Bike position is drastically different between upright and recumbent cycling.

    • I know it’s been mentioned and people one may be more advantageous than the other. But I just think it’s important to recognize the large difference that likely exists.

  2. Cooling: Your inside riding seems to lack a fan? Hard to say from the video if this is your typical setup and workout, but I don’t see any real cooling.

    • For reference, I have 3 of the high flow Lasko performance fans AND 2 of them pull cool air from outside. I have two blowing from the front, and one from the rear. I feel like I am surrounded by wind when I have them all running.

    • I just see you in a T-shirt with a towel around your neck. That seems like it would be extra hot and we know that will lead to higher RPE (Rate of Perceived Effort/Exertion) as well as likely limits as your core temperature elevates.

    • Outside, you are getting tremendous air flow around you that serves as a massive cooling effect.

    • So I suspect you need to analyze your cooling and make sure it is at least as maximized as you can get before calling the power meter into question.

#19

You may already have accounted for this but I once considered performing a static calibration but came to the conclusion I couldn’t get my hands on an accurate enough weight since even good quality gym plates are seemingly unlikely to have an accuracy any better than around +/- 2-3%.

#20

He did mention a test, but not many details.

Would be good to confirm the accuracy of any weight used for that purpose.

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