I did some assist tuning today, testing both low/high gears and low/high PAS. Here’s what I found, maybe someone can explain the mechanics better, but most of it behaves pretty much how you’d expect.
Low sensitivity reads light pedaling as nothing, medium pedaling as light, and hard pedaling as medium. It’s good if you don’t want the motor to engage accidentally with light pedaling (though cadence start usually prevents that unless you’ve turned it off). It also makes the motor feel less eager overall, but if your legs are weak, the motor might not start at all.
High sensitivity detects light pedaling instantly and treats it like medium effort, and medium like hard. I haven’t had any issues with this mode; I like how it gives quicker acceleration from a stop. Even if the watts are low, it engages right away and gives you something to work with.
Low amplification is probably the most useful adjustment for me. It lets you use a “one-size-fits-all” power mode (like 2 kW) by keeping assist moderate (around 250 W) under normal pedaling, but still leaving plenty of reserve power when you push harder. It prevents spin-out and gives smoother, more proportional power delivery. I prefer this setting overall, though on low PAS it can feel sluggish, like the system is fighting for crumbs.
High amplification gives you more power for less effort, ideal if you want to pedal lightly but still get a big boost. It works similarly to high sensitivity, but with a stronger effect. Think of it this way: high sensitivity reads your effort as ×2, while high amplification feels more like ×2.5. The main difference is that sensitivity affects how easily the system detects your pedaling, while amplification affects how much power it adds once it detects it.
Low ramp-up time gives a very quick response, instant bursts that can feel jerky, like each individual pedal stroke is being assisted. It can be useful in technical riding where precision matters, but it feels harsh on high assist levels due to the torque. It’s similar to mashing pedals up a steep hill.
High ramp-up time smooths things out, spreading assist between pedal strokes but letting the motor run off slightly after you stop pedaling. This can be managed with a backward-pedal motor cutoff. Full power delivery feels delayed at first, but it’s barely noticeable once you’re pedaling steadily.
These settings are all situational, but personally I find myself preferring the higher settings for most use cases, and not surprisingly, the defaults are already close to high.
Changing PAS levels often feels similar to adjusting sensitivity or amplification at max pas, since both affect how your pedaling effort is translated into motor power. PAS level directly scales the target power output (like saying “only give me 30%, 60%, or 100% of the available motor power”). However, I sometimes prefer fine-tuning with low amplification at high power (for example, 2 kW) instead of switching to a lower PAS mode. It feels like a more precise way to dial in assist, rather than jumping between fixed levels like 250 W or 500 W. The trade-off is that if you get tired and want to pedal lightly, you don’t have a higher assist mode to fall back on since you’re already maxed out. Also, while I did test all these settings on low pas on all gears and not just high pas, I wouldn’t do any setting adjustments (setting lower than default) for low pas, it just makes the motor extremely weak, sluggish, and unresponsive, which is why I haven’t really mentioned the low pas results. It’s definitely a very situational thing.
Overall, sensitivity and amplification work similarly, the key difference is that sensitivity determines when the motor engages, while amplification determines how much power you get once it does.
