Vado SL and Vado SL 2 assist levels

[Jeremy McCreary]

Does anyone here understand the algorithm that controls this effect in the VADO SL family motors? How does setting percent ranges to tune each mode in the Specialized App actually work?

You might be interested in exploring the basics of this user-tunable power-sensing pedal assist system (PAS) with an interactive graphical model I recently posted.

Visualizing and exploring the power-sensing PAS in Specialized mid-drives — an interactive graphical model

For our more math-minded Specialized mid-drive riders, here's an interactive graphical model of your bike's tunable power-sensing pedal assist system -- hereafter, just "PAS". The model doesn't cover complex PAS responses to transient events like starting out or approaching PAS cut-off speed...

forums.electricbikereview.com

I call this PAS "power-sensing" because measured real-time rider power (Pr) is the main determinant of mechanical motor power (Pm), all taken at the crank. Of course, that makes Pr the main determinant of total power (Pt = Pr + Pm) as well. In a mid-drive, Pt is the mechanical power delivered to the rear wheel before drivetrain losses.

This highly sophisticated PAS surely uses other sensor data like wheel speed and cadence to finesse special situations like starting out, strong accelerations, and the approach to max assisted speed (e.g., 28 mph in the Class 3 mid-drives). No one outside Specialized knows those details.

But Specialized does tell us how the PAS uses Pr to control Pm under routine riding conditions, and that's what I modeled above. Given all your questions, I think you'll find the long introductory text worthwhile. Much of the clearly defined terminology comes straight from Specialized.

You can use the sliders below the graph to set the model for your bike and then explore the implications of changes in assist mode tunings. Pay special attention to the concept I call "saturation". See the intro for details.