Ultra Tuning: Decoding the Voltage Section of Torque Tab

[ProphetZarquon]

First, thanks for the detailed reply!

As a quick Wikipedia check will show, the kilogram (kg) is the SI unit of mass, the Newton (N) = kg m/s² the SI unit of force, the Pascal (Pa) = N/m² the SI unit of pressure, and the Newton-meter (N m) the SI unit of torque.

Mass and force are 2 very different things. A typical digital scale measures weight W (a force) in N but reports mass M in kg using M = W / g, where g is some reference acceleration of gravity in m/s² baked into the scale firmware. Often this g is "standard gravity", with a value of 9.80665 m/s².

Likewise, to get a convenient index B of pedal force F, with B expressed in kg, you'd use something like B = F / g. The index would work as long as you used the same g every time.

Pedal pressure and pedal force are also 2 very different quantities. To get a pressure P from a force F, you use P = F /A, where A is the area over which F is applied in m².


Agree, an exponential progression of the max mechanical power or torque associated with each PAS level would feel more natural. The teeth on the cogs of a cassette grow roughly exponentially in the same way, and for the same reason.

(Not so) fun fact: The Kilogram is no longer based on a fixed mass (such as by measuring the prior samples in Moles, as was suggested), but instead is now measured via the force exerted within a specific known gravitational field; in the process, we've not only made Kilogram calibration now require a (proprietary) device adjusted for each region of the Earth (or space), but also if read very carefully the definition now contains circular logic.

We really should have gone with Moles, despite the drift involved.

 

[ProphetZarquon]

Sorry for being pedantic, but they don't really "stack," as in being additive. They're multiplicative, with the PAS providing an upper limit of power and the Torque/Voltage providing a percentage of that.


I've seen no differences in either between Eco and Sport. All those seem to do is choose which of the 10 levels is available to be selected. If you have all 10 enabled, then there's zero difference.


Bafang has moved on from this model of motor, has changed how their newer motors are programmed. It's unlikely we'll see any changes for the Ultra motors.

Eco & Sport have dramatically different run-on times; they're definitely not operating on the same scales.

 

[ProphetZarquon]

even if you can push to the full 60 kg limit

I weigh ~108Kg at a bit less than 'ideal' weight for my height; so, just standing on the front pedal maxes out the response on every torque sensing ebike I've tried. Generally I don't want to push anywhere near that hard, but when I am, it would be nice if the power assist could continue to scale with my efforts... It doesn't; not even on the new "high torque" motors.

I'm on the lookout for a higher range torque sensor module, to mod a new spline shaft sensor with; higher torque sensors exist, but aren't available integrated into the part I need, so some fabrication will be required.

Most stuff, especially including bicycles & ebikes, is still designed for regular sized people, with those who're excessively tall, or just overweight, left to cope with stuff that simply isn't designed to safely handle us. There was even a lawsuit, but the (very slightly above average height & presumably thought they knew about being 'tall') judge ruled that being far outside normal design specifications by height, does not count as a handicap the way being overweight etc does...

Anyway, yeah, I'm huge, so 60Kg feels like a relatively mild effort for me, but I've yet to find any workaround (other than shorter cranks to limit my force output! ).