The good old manual transmission is one of the few things which have remained more or less the same when it comes to motorcycles. Be it a five or six-speed gearbox, the method of operating a manual transmission-equipped motorcycle is more or less the same: a left hand actuated clutch, with a left foot actuated gear shift. Now, while the gear shift pattern may vary, the method of gear engagement and clutch actuation is pretty much the same.
These days, high-end bikes as well as a few premium entry-level motorcycles come with what is called an assist slipper clutch. This technological development finds its roots in motorsports, and has begun becoming a ubiquitous feature on manual transmission-equipped bikes. Now, a slipper clutch presents itself with a lot of benefits. That said, let’s take a closer look at this useful and convenient feature.
What is it?
As its name suggests, a slipper clutch allows the clutch to slip slightly, in order to reduce driveline lash and sudden, jerky motions especially when downshifting. As it would turn out, executing a smooth downshift rev match requires a lot of finesse, and doing so incorrectly can, at the very least, be quite uncomfortable, and at the worst, cause a crash due to the rear wheel locking up upon deceleration.
That being said, a slipper clutch can be considered a safety device which has the ability to smoothen the imperfect clutch inputs of beginner riders. However, it’s also a tech feature which enables intermediate riders to make the most out of the motorcycle’s transmission, especially in spirited riding conditions such as on the track, or on twisty roads.
How does it work?
While a conventional clutch relies solely on the rider’s inputs to engage and disengage the clutch discs with the pressure plate, a slipper clutch makes use of a complex design which enables the clutch to partially disengage, should the force of engine braking overload the clutch pack. Its design makes use of ramps which are machined into the inner clutch basket and pressure plate. When the engine drives the transmission forward when the clutch is engaged, these ramps force the clutch discs and pressure plate to mechanically press against each other.
On the other hand, when the speed of the wheels is a lot faster than the speed of the engine (i.e., in a sloppy downshift situation, or when shifting down two or more gears with insufficient rev matching), the ramps allow the discs to partially disengage from the pressure plate, thereby causing a slipping effect, which in turn, reduces and smoothens out the effects of sudden, jerky engine braking.
What are the benefits?
As you can see, it’s pretty clear that a slipper clutch provides a plethora of advantages, both for beginners and intermediate riders alike. Apart from reducing the instantaneous and sudden effects of engine braking by downshifting, a slipper clutch also reduces the wear and tear in the engine, by serving as a sort of damper between the transmission and engine, which would otherwise be solely dependent on the inputs of the rider. Lastly, the incorporation of a slipper clutch into a motorcycle's transmission ultimately allows for the use of lighter clutch springs. This results in a lighter clutch pull whcih translates to easier modulation of the clutch, and less rider fatigue, especially on long trips, or heavy traffic situations.
So, should you invest in a motorcycle equipped with a slipper clutch? Absolutely, if budget permits. Apart from the above mentioned benefits, a slipper clutch also provides the rider a worry-free riding experience. Plus, it also enables the rider to learn how to rev match downshift, without the drastic implications of doing so incorrectly.