A quickshifter is a device that allows clutchlessshifting on a manual transmission, and is commonly found on motorcycles. It can increase the safety and comfort of the vehicle since it eliminates the need to use the clutch or throttle before and after a gearshift. Since they eliminate the need to use the clutch and throttle during a gearshift, they are quicker than shifting normally and as such are a popular performance enhancement on motorcycles.
Working mechanism
Almost all quickshifters work on the same basis, a sensor detects the gear shift action, a microcontroller processes the data and cuts off ignition momentarily, resulting in reduction of load at the transmission allowing the new gear to slip into its place. However the method of sensing and reducing the load can vary.
Sensor
Most gearshift sensors work by measuring the pressure change on the shift rod. However, some sensors measure the molecular strain in the shift rod to determine the gearshift process instead of using a pressure switch. The use of molecular strain gauge is costly but more reliable and free from false readings due to vibrations since it has no moving parts.
Microcontroller
The microcontrollers generally control the ignition and/or fuel supply to reduce the load from the transmission when needed. They can be either separate from ECU or a single unit. They can provide near-perfect gearshift in tens of milliseconds.
The load from the transmission is generally reduced by cutting off the ignition and/or fuel supply in the engine, or by disengaging the clutch. Since load is reduced from transmission precisely by the microcontroller, it does less damage to use the quickshifter than clutchless gearshift without a quickshifter on a manual transmission. This process is also called unloading.
Bi-directional quickshifter
The term bi-directional quickshifter means that the quickshifter works on both directions of gearshift - upshifts and downshifts. Most quickshifters are bi-directional, so the term quickshifter is usually alone sufficient. However, exceptions are present such as 2016 Kawasaki Ninja ZX-10R and 2015 H2/R's "KQS" quickshifters which are "mono-directional" and only work on upshifts. Their primary aim is usually to achieve better acceleration by reducing the time interval between gearshifts during acceleration which results in continuous and smoother power delivery to the wheels. Examples of performance oriented motorcycles using bi-directional quickshifter are BMW S1000RR and S1000R, 2017 Kawasaki Ninja ZX-10R and H2/R, Suzuki GSX-R1000/R, Aprilia Tuono etc.
