An oft-repeated argument for mid-drive motors is that they "take advantage" of the bike's gears. How this actually happens is seldom stated, but the usual implication is that the gears are somehow amplifying the motor torque delivered to the rear wheel.
Problem is, this can
only happen when the selected gear's an
underdrive (cassette cog
larger than chainring). In fact, most ebikes are sold with no underdrive gears or a 1:1 at best, mid-drives included. (I look at a lot of ebike specs with gearing in mind. The Vado SL and Creo 2 are notable exceptions.)
Without modification, all available gears on an ebike are typically
overdrives (cog smaller than chainring). And overdrives
reduce the motor torque delivered to the drive wheel. No way around this without an internally geared hub.
As
@mschwett taught me, the entity actually "taking advantage" of the gears on a mid-drive is the rider trying to keep cadence in the motor's sweet spot for efficiency and torque.
And I'd wager (1) that most mid-drive riders don't know that that's their job, and (2) that few watch their cadence or even know their motor's optimal cadence range.
Specialized University put out a video urging their riders to keep cadence above 70 rpm, but I wonder how many ever see it? I just stumbled on it by accident.