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.