I changed from single sided PM (Powertap P1S and Stages) to a single set of Vector 3 dual sided pedals. I have noticed absolutely zero difference in my performance.
(Interesting to note though - I had the Vector pedals replaced under warranty. The original set had me at a 50/50 L/R balance. The new set are 46/54 L/R. Which is correct? Again - zero difference in my performance.)
I’ve been wondering how people can even be assured that dual power meter pedals read the same and give an accurate left/right balance.
I have a Stages and I’m pretty happy. It’s consistent. IMO, mostly you need a good test on your power meter and then you’ll know you are training in the right zone. Most Importantly you need to know when you are above and below threshold and you should be able to confirm that with RPE as well.
I’ve ended up going with a left sided meter, and I don’t think about having one for the other side. I actually was in your boat when purchasing the PM. I wanted a spider based meter for left and right metrics. But have been more than happy with having just the left sided meter for a few reasons.
Power meters provide metrics, at the end of the day it’s a tool that lets you measure and see progress. It’s considered real dub if you just went to the gym and lifted weights without ever looking at what weight you’re actually lifting. I see a power meter in the same light (if you’re serious about building your fitness then having any baseline and process to measure progress is good).
Less complexity: sometimes dual sided meters can cause extra complexities (ie gp lama did a video on a stages left and right meter where using the combined power was causing issues/drop outs etc). The same can be said about some of the shimano power meters.
Less cost: I know this isn’t an issue for you but saving that extra money and putting it into a trainer or something else (like your varia: which I have and love by the way, can’t recommend enough), getting an actual bike fit that will help you ride more, longer, and build your fitness. I always try and maximize my time on the bike and rides through finances because you’ll always remember some sweet rides with friends but not really remember the fact that you had dual sided power on a gravel ride with buddies.
There are some downsides to having a left sided only (ie power imbalances (every one varies we’re not a perfect 50/50 split, lack of pedal technique/smoothness, general efficiency (all of these things can actually be overcome by doing one legged hill repeats up moderate climbs where both feet remain clipped in but one foot does the power dumping (there is a good podcast on this as well, forgot the name but if I remember I’ll edit and share the link).
In my honest opinion I think single sided is good enough for most people (even froome rode single sided for a very long time. That being said if you’re very serious about using a dual sided meter, going into the metrics, want absolute power (want to know about pre-existing imbalances) etc then I would say go for a double sided meter.
Hope this helps a little bit, and if you decided what did you end up going with?
I’ve never heard of anyone doing anything actionable with their left/right balance.
The bottom line is that you need to know your threshold. You can find that with any type of power meter and some basic testing. Once you know threshold you can find your zones.
No training needs to be to the exact watt. You get the effort above or below and in the desired zone and do the work.
The big picture view is whether you are training the aerobic system or the anaerobic - above or below that threshold. You cross calibrate that with RPE and how it feels.
I think sometimes people make this too difficult.
Four bikes, four power meters, all single sided, no regrets.
Vector on my road bike has been wonderful, Stages on my gravel is shit, 4iiii on my XC bike (newer to me) has been great, and Cinch on my Enduro has been great.
I know there will be some inconsistencies between them, but they will be close enough for my purposes. If I added in an extra variable of dual sided, it would be worse.
I started my PM ownership with a Power2Max single sided. Migrated to Powertap P2 with bike change and different BB spec. The dual sided was neat. Fortunately for me, I was always very, very close between legs, like always within 1%. After many years of riding, it was just natural. A little over a year ago I got a pair of Favero and went single sided knowing I’m never very far off. As a matter of fate, my P2’s started having problems last fall after almost four full seasons. I communicated with manufacturer and sent them back for service. They stated right side crapped out and couldn’t fix, but I could operate single side just fine, or they’d discount me on new pair of dual sided. I just had them service the one that was functional and didn’t think twice. If you think you are so far off it’s impacting you, try dual sided. Gives you the chance to correct (or at least try). Otherwise, single sided and save the money to buy new tires.
yes, if buying for the first time my first choice would be a spider based total power unit like Power2Max or Quarq. If I had two bikes, or traveled and rented bikes, then I’d be more inclined to go with pedal based like Garmin or Assioma.
Thank you for serving. AWSOME PICTURES!!!
My first power meter (currently on my TT bike) is a single sided Favero BePro S. It would be interesting to know what power my right leg puts out; I suspect it is more than the left (or at least that’s what I tell my self, my excuse for my power reading being too low 
). I wasn’t (still aren’t) disappointed with it, so I had no hesitation in buying a single sided 4iiii for my road bike last year.
I would buy the double sided model in case one side stops working, you will still get useful data. Dont buy the Garmin Vector 3 like I did because the right pedal does not work properly half of the time. Next time, will buy dual-sided Stages hoping that the product is more bug -free than Garmin Vector 3.
Gaëtan Boulanger
Why buy half a power meter?
Half the price.
Just bought a new bike with a double sided power meter and sold my old left side stages one. I’ve found I’m stronger in my right leg by between 2 to 5 percent. The more tired I get the worse it gets.
So it seems in my case the old meter was ready low.
You could export the data and import it into something like Excel. Plot it against power, cadence, and crank torque.
I wonder if the cohort of left side power meter users would have L/R thigh circumference ratios different from users that train with whole power.
No regrets with either of my 2 left crank pms.