Never heard of a big power diff between left and right leg. Cycling friend found it useful after injuring one leg. But single sided PM is more than adequate for most of us unless you are PRO 
. Also from my limited experience, PM are rarely used in races as you don’t have time to check
People are fussed because the left only options cause discrepancies in many cases.
- The L/R balance on a spindle/spider based system is made up.
- The L only crank systems can vary a lot as your legs fatigue.
- If you use left only to hit power targets, it’s easy to find yourself favoring your left leg.
- If you have an imbalance that varies a bit, it will be multiplied in some way.
My experience is that I own a left only crank based unit that’s been incredibly stable over time. The unit has it’s limitations. (5-10% variation in my case).
If you want to use a single sided setup you need to take the above points into account.
Don’t really see the point of dual sided. However, a friend did suggest to me that you could get dual and put one pedal one of your other bikes. Obviously everyone has more than one bike!
I think this is worthy of repeating, I definitely favor my left leg when trying to hit certain numbers. Especially prevalent on anything above FTP in my experience. I wonder if certain workouts would be easier to maintain with a dual sided meter?
I’ve noticed on my rides the pedal imbalance can be up to 46/54 either side. Sometimes left, sometimes right, sometimes 50/50, mostly about 1 to 2% either side.
I don’t fuss about this in terms of my riding, but with only a left power meter, if I were to swing even from 47% left on one ride, to 53% the next, the power reading would vary greatly for the same actual power. If you’re riding sweetspot or beyond workout based on those numbers it’ll make a big difference to RPE.
Outside this isn’t going to worry me so much either, personally I got vector 3 peddles and thought it wasn’t worth it, 6months later with hindsight and since I’m using them on the rollers I’m glad they’re dual sided.
That is just it…imbalances usually don’t. Some are more pronounced in higher intensity sessions, some even change sides depending on intensity, etc.
Again, if you aren’t looking for much more than average power for a ride/ longer intervals, pacing, etc. a single sided option is a great affordable unit and will meet your needs. But if you are data-focused and analyze in high detail, you are better off with a dual-sided / spider-based PM.
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I think the dual sided pedal systems work by having the right pedal signal to the left pedal, then the left pedal broadcasts to the rest of the world. So you can’t use only the right side. I’m sure someone will correct me if I’m wrong 
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You are correct. Dual sided PM pedals cannot be split to two bikes.
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I would factor in the types of ride you do. For long and steady efforts where pacing is key I think is very justifiable to go for dual side although I agree that single side would do a satisfactory job.
I have a vector 3 duo which I flip between my road and tt bike. On my gravel bike I have a one sided 4iiii.
I understand that the imbalance can shift with power or with fatigue. But the premise of the OP is that you are strapped for cash and already have an accurate power meter (built into the Kickr) that measures total power accurately. Given the OP wants to do crit racing, I doubt he’ll be looking at his power meter much. (For the sake of his competitors, I hope he doesn’t.) So realistically, he will use a power meter to compute TSS or to pace his rides in non-race situations. For that a single-sided power meter is plenty.
If you have the budget, you should get a power meter that either measures total power or left and right power separately. But a single-sided power meter is not as bad as you make it out to be.
I think we are saying very similar things…I made a point to emphasize exactly what you are saying - if you are on a budget and aren’t looking for incredibly minute details (ride average power, TSS, etc), a single-side PM is a great option.
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I ride with the Vector 2s single sided pedals and they work great. You CAN artificially inflate your numbers if you focus on stomping that left leg, but you can see it happen on the screen and easily avoid doing it. Just ride as normal and it isn’t a problem. The ONE downside to single sided with TR is that Individual Leg Drills don’t work. You can ignore the ILD power targets in standard mode, but you can’t do them at all in ERG. As for the L/R balance… as long as you’re using the same meter on every TR workout, you’ll get faster. Accuracy doesn’t necessarily make you faster, PRECISION and CONSISTENCY do.
Well to conclude I realised I had a new cycle to work voucher waiting for me so splashed it on the dual sided vector 3’s and upgraded some of my groupset to duraace. After making sure the power meter read the same as my trainer, I took them out for a blast and realised (by comparing speed/power/HR) that I had been over reaching way too hard in the past when I only had speed to gauge performance outside. These are going to help me pace my outside rides significantly!
Thanks for all the insights I learned a lot from this thread
Oh yeah - the power meters report that I have a L/R imbalance of 52%/48%. I’m not that worried about it