Running a single sided Assioma and I honestly can’t justify spending 430€ to make it double sided.
It is ~10 watts off at 250watts compared to my neo2 and the power measurement might be a little more erratic than a dualsided version. But over an interval it evens out and barely makes a difference.
Considered getting the upgrade kit once, looked at the price and never thought about it again.
I had a single sided Garmin Vector for years and loved it. When it was time for a change, I switched to the dual sided P2, and am happy with these as well. Buy yourself something else with the extra $$.
If you’re worried about left/right leg imbalances find a gym with wattbikes and do a few workouts, you’ll be in formed about any imbalances. A lot of people are talking about Stages dropping their prices but check out 4iiii’s they’ve reduced some of theirs also. I’ve used single sided (4iiii’s) for years and they’ve worked brilliantly.
Zero regrets (4iiii left-side 105 crank). The three bikes on which I install it are all Shimano circa 2005 (one Dura-Ace, two Ultegra), but they all work with the 2018 4iiii 105 crank because they are all Hollowtech… thanks Shimano for making a standard and sticking to it!
I don’t really like moving it from one bike to another even though it only takes a few minutes.
Maybe I have a leg imbalance, maybe I don’t. I really don’t care… I’m still able to do structured training and pace myself on non-training rides, and that’s all I really care about.
Doing single leg drills during TR workouts is kinda awkward 
Both sides (hah get it?) are making great points here. I think also, deep down my fear would be that nagging voice in the back of my head saying “what if you have a 40/60 % imbalance?” I’ll never know with a single sided. Maybe ignorance is bliss.
I have Faveron Assioma Duos. With the exception of the first few rides after I bought them, I’ve never looked at the data comparing my left-right balance, so I wouldn’t buy dual-sided for that. Is the dual-sided more accurate? I’ve never had a single sided, but I can say that I frequently compare the Assiomas with my Kickr Core and there is usually a 2-3 watt difference at the most. So I’m very confident in the accuracy and consistency of the numbers I get and that is valuable to me.
I had a left side stages PM. It was nice, but my l/r split varies with power, and the imbalance can be 5% and up. I sold it after about 9 months. Maybe I the future I’ll get a quark or something else dual sided, but for now I’m fine having no PM on outside rides.
Yes, regrets.
Like many I started my powermeter career with Stages. Rode them on my bikes for about 1.5 years. Then I got a dual sided pm. And I started noticing huge differences, especially when riding longer or when riding SST intensity (which happens to be my main race intensity, as well). The key moment was when I compared two race files from the same event. Same course and so. The one sided wattage did not make sense.
I got so intrigued that I bought an additional pedal pm to get a real L/R balance. What I noticed, my weak right leg would fatigue quicker. And this was also the explanation why it cramped more often. I spent an entire winter to fix this imbalance and was quite successful with that.
What really annoys me, should have bought a dual sided right from the beginning. I consider FTP tests and zones and these things as highly irrelevant. However, understanding what wattage I can produce under which conditions is the real value in a pm for me. The more quality data you have the better. I’ve lost over a year with the one sided because I got crap quality data from it.
I am very happy with my 4iiii Precision left-sided power meter.
Very accurate and it improved my training over the 2-years so far.
Highly recommended.
Single, no regrets.
Fortunate enough to own 2 actual power (hub, spider) units and 2 left side (stages) - no regrets or concerns and the left side get the most use by a large margin. While I prefer the actual power in use (quicker readout, for example) the left side still get the job done.
It’s funny reading this thread you can walk away with no solid answer. Most who have single seem perfectly fine with it, those who have dual seem perfectly fine and can justify the extra cost. You get a small percentage that found out they do have large imbalances and they benefit from a dual. My opinion hasn’t changed, if you get a consistent number then that number is good enough to train with. If I come across a good deal on a dual (maybe used) then I’d probably go for it. If I come across a good deal on a single then I’d go for it. For me, if I ever buy a new dual PM I’d go with the Assioma Pedals at their price point.
In 2015 I got a gen2 stages, it was a nice introduction to training with power but there were no other positives besides the price (which wasn’t even that low). I dealt with water ingress and dead batteries for the whole time that I had the unit. At about the one year mark the unit completely died on me at my team training camp, I had to pay to replace/upgrade to the gen3. I used the gen3 for a year thn upgraded to Quarq. I never looked back, the Quarq has followed me across three bikes and I regularly swap it between my bike in Europe and the US.
The two vs. one sided power doesn’t matter that much but if I can have a quality, reliable unit like the quarq and it happens to measure total power it’s just a bonus.
I have a Cinch meter on both bikes for consistency (left only power). I find it annoying that in order to hit challenging numbers or even maintain steady wattage I have to focus on pushing harder on my left side.
Can’t wait for SPD power pedals. Get dual sided power.
Yes, I find it jumpy for live readings. I have Vector 3s. Considering upgrading.
Was in your situation a few months back. I went to my local gym and did some tests on a Wattbike with a dual power meter.
After 3-5 workouts I learned that my pedal L/R ratio is 49:51. Based on that I decided that I don’t need a dual sided power meter.
A week later, I bought the Favero Assioma Duo (a dual side power meter) because trying to rationalize these bike upgrade purchases is impossible and I just want to have a good peace of mind and don’t worry about inaccuracies.
So, I don’t need it but I bought it anyway and no regrets.
Get dual-sided if you want to compare to your friends. Single-sided is perfectly adequate for training and racing.
Probably important to remember that consistency matters most in training - accuracy is pretty worthless except for comparing across bikes/PMs/performances. If you have an imbalance, it shouldn’t matter as long as it is consistent. With a L-sided only PM, you might not get numbers that you can compare favorably on Strava but you will be able to index your workouts perfectly fine and compare outdoor performances without any problems.
Full disclosure, my first PM was a dual-sided, but I quickly realized that the dual-sided data was pretty worthless if the goal is to get faster, not measure more watts. Since then have three x 4iiii installed with zero problems and love them.
No regrets here, I bought the Stages gen3 Shimano this past Christmas on a holiday special. I was aware of some discrepancies from others and reviews and quite honestly, power readings and accuracy is pretty close for my needs.
I’ve been using a stages left side power meter for more then three years. Absolutely no regrets, and great value.
When I start measuring my run stride length to compare left and right discrepancy, then I’ll insist on a dual sided PM. But that won’t happen any time soon, and doesn’t need to in my opinion!