Hi,
I’m considering Favero Assiomas to replace my Vector pedals (which suffered from a ton of issues). My Vectors were “3” meaning that it was the dual-sided system.
Would you recommend to stick with that and go for the duos or “just” the unos (one side power)? What are the pros/cons?
Thanks
There is only one pro for a single sided product measurement - it’s cheaper.
But the con is a big one IMO - it’s only estimating your total power, not measuring it.
Assuming you have two legs, a single sided power meter solution measures output from one but not the other. It then makes the assumption that your total power output is double that being measured. That’s a very big assumption.
People can have significant differences between left and right, and it’s probably not stable either. It’s very likely to vary with intensity, position and fatigue. So you’ll never know, to any decent level of accuracy, what your power figure is. Even if the meter is measuring to say 2% accuracy, that only applies to what it’s measuring. The uncertainty of any total power figure extrapolated from that could be far worse. An instrument can only state an accuracy for what it measures. If you want to actually know what your output is you need either a total power measurement like you’ll get from a hub or spider power meter, or a pair of pedal or crank power meters.
+1
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There is only one pro for a single sided product measurement - it’s cheaper.
But the con is a big one IMO - it’s only estimating your total power, not measuring it.
Assuming you have two legs, a single sided power meter solution measures output from one but not the other. It then makes the assumption that your total power output is double that being measured. That’s a very big assumption.
People can have significant differences between left and right, and it’s probably not stable either. It’s very likely to vary with intensity, position and fatigue. So you’ll never know, to any decent level of accuracy, what your power figure is. Even if the meter is measuring to say 2% accuracy, that only applies to what it’s measuring. The uncertainty of any total power figure extrapolated from that could be far worse. An instrument can only state an accuracy for what it measures. If you want to actually know what your output is you need either a total power measurement like you’ll get from a hub or spider power meter, or a pair of pedal or crank power meters.
Very clear explanation - thank you! I’ll go for the duos!
From a training perspective, would it be relevant to do some strength workouts focused on the « weaker » leg in order to equalise both legs power outputs? (Assuming they’re different)
There is only one pro for a single sided product measurement - it’s cheaper.
But the con is a big one IMO - it’s only estimating your total power, not measuring it.
Assuming you have two legs, a single sided power meter solution measures output from one but not the other. It then makes the assumption that your total power output is double that being measured. That’s a very big assumption.
People can have significant differences between left and right, and it’s probably not stable either. It’s very likely to vary with intensity, position and fatigue. So you’ll never know, to any decent level of accuracy, what your power figure is. Even if the meter is measuring to say 2% accuracy, that only applies to what it’s measuring. The uncertainty of any total power figure extrapolated from that could be far worse. An instrument can only state an accuracy for what it measures. If you want to actually know what your output is you need either a total power measurement like you’ll get from a hub or spider power meter, or a pair of pedal or crank power meters.
Very clear explanation - thank you! I’ll go for the duos!
From a training perspective, would it be relevant to do some strength workouts focused on the « weaker » leg in order to equalise both legs power outputs? (Assuming they’re different)
I think the general consensus is that it’s not worth worrying about in most cases. From the comments I’ve seen it seems that plenty people have a fairly significant imbalance but it’s not necessarily a problem. I would imagine it’s worth looking at the cause if you think it’s due to an asymmetrical posture on the bike, perhaps due to different leg lengths or something, but if you just have a dominant leg and no pain or problems, it’s probably a non issue.
Ok that’s pretty much what I thought but thanks much for confirming 
.
Hi,
I’m considering Favero Assiomas to replace my Vector pedals (which suffered from a ton of issues). My Vectors were “3” meaning that it was the dual-sided system.
Would you recommend to stick with that and go for the duos or “just” the unos (one side power)? What are the pros/cons?
Thanks
IF you have very good leg balance, I suppose that single sided works OK. If you don’t, it gives absolute junk numbers. I am very significantly left leg dominant. As a result of picking up a second hand bike for my wife recently, I had a chance to run a Stages left-only PM at the same time as my Quarq. My Quarq has been very consistent over the years, I’ve verified it with a known weight, and it matches my Computrainer and my wife’s Quarq.
Ride 1, 22.7 miles
Quarq average power: 116
Stages AP: 128
10.3% difference.
Ride 2, 23.6 miles
Quarq AP: 156
Stages AP: 174
11.5% difference.
If 10-11% error isn’t junk data, I don’t know what is. I personally think single-sided power is a waste of time.
I went uno with the intent to upgrade when finances allow. I wanted the option of biking with power in the alps and I didn’t have dual sided money at the time. The thing I have going for me is that I was coming off of stages single sided so at least I’m working with similar numbers and I am able to use my training power numbers.
It didnt really matter what my actual power number was climbing the mountain, it did matter that I metered out my effort correctly based on my training and considering I’m going left side only to left side only, it worked.
If you are starting at dual sided and then going to single, then there is an issue.
Does it matter though? It could add a zero on the end or use completely different units but as long as it’s consistent then you can train and race at proportions of whatever number it gives out.
Does it matter though?It would not matter if your much to training if your imbalance never changed. But if your power balance changes based on fatigue, intensity, cadence, position, etc., then the number could float around by a lot.
Because left/right balance probably isn’t consistent. I am left leg dominant at high cadence, right leg at low cadence and then it also varies with intensity. I have power data that shows that a left only PM would show my power fluctuating by 20-30w simply by shifting gears while my dual PM has the power steady. As a result if I was using a left only PM and shifted gears in the middle of an interval on the trainer, it would suddenly feel a lot harder to hit a power target (because the left only was under reporting). What conclusion would you come to in that case? You would think it’s just harder to pedal at a lower cadence, which would be wrong (in this case).
Does it matter though?It would not matter if your much to training if your imbalance never changed. But if your power balance changes based on fatigue, intensity, cadence, position, etc., then the number could float around by a lot.
Good point. So does anyone with a dual sided have the numbers that show the balance does change significantly or not?
Regarding the OP specifically, if they’ve had a dual for a while then presumably they should know if it’s a factor for them or not.
Yes, my quarq shows I’m 35-65% during zone 2 rides, about 40-60% in tempo, and 45-55% at higher intensity. At no time I’m getting close to 50-50. Stages or any other single side PM is a waste of time for me. My imbalance is not an issue for me, just how I was made, I guess.
Garmin Connect shows it, but it is not easy to export and deconstruct. My average balance is around 53%/47%, but when I look at the detail chart in GC, it swings from 60% L to 57% R through the course of a ride. The best summary data I have is at a 5 mile split. I looked at a ride that had some mountain climbs, and even at the 5 mile splits, it varied from around 52% L to 55% L. That is a 6% inaccuracy swing. At the start of the ride, when I was fresh, I was 52%/48%, but then it drifted from there.
Does it matter though? It could add a zero on the end or use completely different units but as long as it’s consistent then you can train and race at proportions of whatever number it gives out.
It sure matters if at some point you switch to a real power meter and you don’t know if the difference from your historic numbers is due to training or due to the inaccuracy of the power meter. I regularly look at historic data for my mean max curve and that would be completely useless if I had data that didn’t compare.
Not only that, but my leg discrepancy gets dramatically lower at high power, and I understand this is not uncommon. In other words, your fixed offset is useless since the discrepancy varies with the duration. To illustrate this, I’ve done some further data analysis of the rides I just posted. I used one-minute power rather than max power since max power is subject to inaccuracy due to the limitations of one-second power capture:
Ride 1, 22.7 miles
Quarq average power: 116
Stages AP: 128
10.3% difference.
Quark 1 min power: 232
Stages 1 min power: 229
-1.3% difference.
Ride 2, 23.6 miles
Quarq AP: 156
Stages AP: 174
11.5% difference.
Quark 1 min power: 252
Stages 1 min power: 255
1.2% difference
Any further questions?
I think less discrepancy at higher intensity is quite common, at least for me a couple of other guys I know. I’m the extreme case, from 35-65% inbalance at lower intensity to 45-55% at higher intensity.
I say forget about the discrepancy. The Uno is fine.
Let’s assume you DO have a 5% discrepancy between your right and left, and you know about it. What are you going to do about it? How is it going to change your training or racing compared to if you had had an uno and not known about it?
It’s not. It’s not like you are going to push down harder with that one leg that produces 5% less power at certain intensities.
Even if it caused you to focus on more on trying to equalize your pedalstroke in training, it’s arguable that you’d be better off just spending that time just training as you normally would on the bike, and getting both legs stronger.
I’m not an expert on powermeters though, so I’m open to changing my mind if someone has a convincing argument about how the double pedal power will impact training more than single.
It can depend on what you are using it for. I have a bike I just use for commuting on - not training. I have a single sided meter on there just to get some reasonably accurate TSS for my commutes, more to make sure I am not over training when I commute outside than anything else. On my road bike and my race bike I have double sided meters and would not really want to entertain a single sided meter.
There is only one pro for a single sided product measurement - it’s cheaper.
But the con is a big one IMO - it’s only estimating your total power, not measuring it.
Assuming you have two legs, a single sided power meter solution measures output from one but not the other. It then makes the assumption that your total power output is double that being measured. That’s a very big assumption.
People can have significant differences between left and right, and it’s probably not stable either. It’s very likely to vary with intensity, position and fatigue. So you’ll never know, to any decent level of accuracy, what your power figure is. Even if the meter is measuring to say 2% accuracy, that only applies to what it’s measuring. The uncertainty of any total power figure extrapolated from that could be far worse. An instrument can only state an accuracy for what it measures. If you want to actually know what your output is you need either a total power measurement like you’ll get from a hub or spider power meter, or a pair of pedal or crank power meters.
Why does it matter?
Asked Coggis this and he said it doesn’t
As long as it’s consistently off or accurate
It’s not like you are going to push down harder with that one leg that produces 5% less power at certain intensities.This is exactly what is happening. Those who have a dual-sided PM can see it in their data. And it changes with fatigue, cadence, and position too. So, a single-sided PM might show wildly fluctuating power (±5% is not out of line) when actual power is actually quite stable. Or the opposite. The thing is, actual power could be 10% off from displayed power on a single sided PM, and that might matter to people.