I wanted to get a recommendation for a workout that would allow me to measure power imbalance across different power bands, cadences, etc. I have access to a Wattbike that I’ll use for the test.
I am having surgery to correct an issue affecting my pedaling and would like a before/after comparison.
Ramp Test 
Good point and I was probably overthinking it by not just using a ramp test. Will have to pick a quiet moment, as the Wattbike is in a gym and I like doing ramp tests on my own at home.
I think a ramp test is fine but I probably wouldn’t do a TR type ramp. I’d do longer stages (5-10 min) so you give your body time to settle in and then you can really look at the data afterwards. You could use even longer stages below threshold and benchmark your imbalance over multiple tests. Like,
10 minutes at LT1/Zone 2
10 minutes between LT1 and LT2/FTP (tempo)
10 minutes at FTP/LT2
5 minutes at some percentage above FTP (105%-110%)
2 minutes at 120%
You could toss any of these tests into any trainer ride and then note the results in a spreadsheet. You don’t even have to do every test all in the same ride.
I think something around 60%, 90%, 110%
60% so you can see how your doing with lower effort. I see that my L/R balance is a tad looser at the lower efforts.
90% should be something where your using all your muscles
110% see if your using one more then the other while really digging hard.
My L/R balance is 49/51 when going easier like a recovery ride. When I am pushing hard I have noticed I am closer to 50/50 my personal experence is the reasoning behind my idea on the %'s
I’d go for a long ride before you try whatever test to see what your balance looks like when fatigued
