Gear Shift Assist Pro - How it works

[Grumpy Goat]

Just came across this 2014 article thanks to Bruce. It describes exactly how the GSAP on our bikes work, so I though I would share it here.

The main excerpts:

Electronic operation

• During an upshift the system senses the movement on the shifter and when it passes a threshold, cuts fuel injection for 50–100ms to relieve torque on the driveline and enable the next gear to engage.
  
• During a downshift, the system senses the movement on the shifter and when it passes a threshold, adds enough fuel to relieve driveline torque, then readjusts fuelling to match the rev of the next gear down, which occurs over 100–150ms—basically the same principle as double declutching squeezed into a timeframe of about 1/10 second, or two virtually instantaneous blips of the throttle.
  

And here is the practical bit:

GSAP shifting (not using the clutch)

• Upshifting requires the throttle to be open with the bike accelerating (even gentle acceleration). Downshifting requires the throttle to be fully closed with the bike decelerating. Any deviation from these two rules will result in a rough shift.
  
• Works in all gears on and off road once the bike is in motion—you must use the clutch as normal to move off and also when coming to a complete stop.
  
• Once you are accustomed to the operation of the system it is particularly handy when riding in conditions which require a higher number of gear changes—for example, in urban areas or twisty mountain roads.
  

On my bike, backing off on the throttle while pressing the gear lever results in a smooth downshift. The throttle grip does not have to be fully forward to the stops.

[BC_Rob]

My down shifts are so much smoother than my upshifts. I never use it for upshifts… too crude.

[Podman]

That's interesting because I pretty much use it all the time and just use the clutch when stopped or getting into first.A fair amount of time it is quite smooth although it does give me a kick every so often. The one thing I noticed is that as I put more miles on the bike it get's better (presently at 10,733).

[L2RKE]

Mine only seems to work well if I am on full throttle for upshifts. But I don't generally ride that way, so rarely use it.

[Grumpy Goat]

So the last 2 other bikes I had / have (2014 BMW S1000R and 2019 Tracer 900 GT) both have QS up only and both are smoother than the GSAP (up) on the RS.

All three bikes shift smoother using the QS, the more the throttle is twisted while accelerating - keep the throttle in one position (static) while shifting up without the clutch and the jerk will be worst. Keep twisting the throttle gently while shifting up and the jerk will be much reduced. Twist the throttle in anger and shift up and you'll likely get the smoothest shifts.

The RS jerks in the 1-2 shifts more than the other 2 bikes, and 2-3 is less jerky. All other upshifts are very smooth especially if the rate of twist of the throttle is changing. The Tracer has the smoothest QS of the lot and the S1000R was between the two but the most violent.

Shifts with a quickshifter have to be quick.

[SoCalR1200RS]

Interesting, you found your S1000R to be the most violent. My S1000RR was always butter smooth to the point where I only used the clutch at stops. All other shifts I'd either use the QS. On the RS, I find myself preferring to pull in the clutch with each shift as the QS jerks, but as you said, it's mostly with the lower gears, and when I rev up to 5,000+ RPM before shifting. If I shift at a lower engine speed it's smoother, but still not as smooth as the clutch.

[Lee]

Interesting, you found your S1000R to be the most violent. My S1000RR was always butter smooth to the point where I only used the clutch at stops.

I was also surprised by that statement. Maybe we're not understanding what he meant.
I tried a friend's S1000RR and found the shift assist  much smoother than my R1200RS and R1250RS. It was also a little smoother than my K1300S.

[runnerhiker]

Interesting, you found your S1000R to be the most violent. My S1000RR was always butter smooth to the point where I only used the clutch at stops. All other shifts I'd either use the QS. On the RS, I find myself preferring to pull in the clutch with each shift as the QS jerks, but as you said, it's mostly with the lower gears, and when I rev up to 5,000+ RPM before shifting. If I shift at a lower engine speed it's smoother, but still not as smooth as the clutch.

My experience is like yours.  I have a 2019 S1000XR with a buttery smooth QS that is the best, I only use the clutch at stops.  My 2020 RS and my previous 2016 RS have/had QS that are abrupt in lower gears and I use the clutch a lot.

[Grumpy Goat]

Interesting, you found your S1000R to be the most violent. My S1000RR was always butter smooth to the point where I only used the clutch at stops. All other shifts I'd either use the QS. 

Oh no, I didn't mean the QS on the S1000R ... I mean the bike as a whole compared with the RS or the Tracer. The word was for emphasis. Of course you could ride it gently but that was not its nature. Twist the throttle hard and you would know the meaning of the word. I suspect the RR was even moreso.

No the QS on the S1000R was just fine.

[Ray]

Agree with the impression of the RR. In spite of ~200 HP, it's the smoothest superbike I've ever ridden. Unless one has no control over their right hand, nothing violent there. And for those who have no control, there is always rain mode to keep it peaceful.

[Masione]

I found a BIT of preload on the upshifts can smooth out the process...

[MrVvrroomm]

I found a BIT of preload on the upshifts can smooth out the process...

Preloading shifter, not sure if you're just touching it or actually putting pressure on it, will actuate the GSAP if upshifting with throttle position more than closed.

[DRS]

I am very new to quick shifters but I swear that the "throttle blip" happens at times even when I'm using the clutch. This is only at low speeds like approaching a traffic light. Has anyone else experienced this?