You've nailed it! The SL 1.1 motor is the most efficient at the cadence between 80 and 90. Pedalling as fast makes the motor lively and strong. On contrary, pedalling at a low cadence makes the motor weak and inefficient.
Going with the 36T chainring sounds like a plan. However, you could consider going even more extreme, that is, installing a 32T chainring, which is the smallest 104 BCD ring of them all, used on mountain bikes/e-bikes such as Levo SL. I went totally extreme with that by installing not only the 32T ring but also replacing the drivetrain with Shimano M5100 that has a 11-speed 11-51T cassette. That conversion gave me the lowest gearing of 18 gear-inches, which is purely in the MTB domain. (I use a 116 link chain in this configuration).
The consequence is I can climb anything but my max speed at favourable conditions is 32 km/h before I max out on the cadence. I do not care! The low gearing forces me to pedal at a higher cadence, which makes the motor work efficiently, and I am less tired on long rides as I do not need to pedal hard only fast.
When the chain gets worn, I'm going back to a 36T chainring but keep the 11-51T cassette and M5100 derailleur/shifter.
Vado SL satisfies my needs in higher assistance modes. For solo rides, 55/55% (or 30/100%) assistance gives me a long range at a moderate speed. For group rides (assuming my Fearless is in the derestricted state):
- 60/60% is for riding together with normally healthy people (who are not 'snails')
- 80/80% is for riding with athletes in the gravel domain...
- But 100/100% turned out to be not enough to catch up with 'horses' riding asphalt on their gravel bikes, even with a bigger chainring
Bear in mind my bad legs can only provide some 80 W average! High assistance requires multiple Range Extenders for long rides, and I did not hesitate to buy one after another until it was still practical
Riding with the 'snails' is the most horrifying for me. I am the best to ride with them with the assistance OFF but riding without any assistance makes me exhausted...