KNOW YOUR R… SLIPPER CLUT TCHES
It’s only when you ride a bike deprived of a slipper clutch that you come to realise just how genius and essential these fancy sounding plate spinners are. To get a fuller grasp of how they work and who they’re aimed a at, we had a chinwag with Sigma slip
How good will a normal clutch hold up on track?
It will work as it’s designed to, but then you’ll be doing things that it wasn’t designed for: if you’re arriving at a hairpin heading down the gearbox the clutch won’t be equipped to deal with that, meaning you’ll get jerk from chain, through the clutch, and into the engine. A regular clutch is always going to be as good as the environment it’s designed for – most aren’t designed for savage track riding. Going back a few years some of our early customers on board Ducati 916s at Donington used to actually knock out their primary gears going into Melbourne loop. It’s just too brutal, unless your name is Mick Doohan and you can perfect the clutch slip with the engine yourself…
How will a slipper clutch benefit a bike?
It will make life that much easier on corner entry, meaning you can focus on yourself and lap times. It does this by slipping the clutch at any point where your behaviour is likely to make the rear wheel hop, therefore taking the stress out of the drivetrain which in turn stops the chain beating up the rear tyre. If set up correctly it will give more side grip all the way to the apex on the rear rather than the engine needing the grip to force it to turn over. You feel it as engine braking – it’s not! As you brak ke hard into a corner all the weig ght is on the front, but with the throttle closed the chain geom metry will want to pull the rear whe el off the ground; the slipper clut tch helps keep the rear wheel on t the ground and so keeps the back k wheel behind the front.
How does it work?
Each clutch has a series s of ramps, typically one betwe een each spring. When the engine e turns the wheel, the clutch operates normally, but when it’s the other way round (so slow wing down), the centre rises and pokes the pressure plate off th he clutch pack and lets the clutch h slip a little. All in all, this mea ans that the rear wheel won’t try to overcome the engine braking and will help to combat the b back wheel hopping on corner entr ry!
Would it help on the road?
Yes and no – a slipper clutch is made for a higher level of intensity than popping down to Waitrose, so unless you fancy going road racing it probably won’t work that often. Unless of course you’re a getaway rider of some description then it might just come in handy...
How should you maintain one?
The same as with any clutch. As the plates wear down, the pressure plate drops down, which will mean that the clutch
starts slipping. This is incredibly bad for the engine as the clutch isn’t being held together enough to handle the power – if this happenspp youy have a big gp problem. At the first sign of the clutch slipping, you should check the plates for wear and replace them if needed.
What difference does adjusting the clutch slip give?
Essentially, the clutch needs to be held together hard enough not to slip going forwards, and once that’s okay you can have more spring for more engine braking and adjust it to the rider’s preference. You need it to hold together enough to actually work, so we set the maximum ramp angle (how much it slips) and recommend a spring to work with it, but the end user can adjust it to suit their preferences from there on. It’s a very personal item that can be tuned specifically, like an instrument.
What’s the best way of using one?
At the end of the day, a slipper clutch is essentially there to assist you, which means it isn’t an automatic system. It will work without using the lever to shift down the ’box, but we don’t recommend that. Not using the lever will destroy the clutch plates a lot quicker so be aware of that. When you first start using one as well it will probably feel slightly alien; this is because it will feel like the clutch lever is clicking in your hand where the clutch is actually operating on the other end of the wire. It will all become natural with time, so don’t overthink it.
Do they work with modern bikes and auto-blippers etc?
Auto-blippers are incredibly helpful and are a welcome addition to performance machines, and will work extremely well alongside a slipper clutch unit if they are designed to work together. The perfect machines are more like your pre-electronic Supersport, Superstock and Superbike machines, as you really need to have either sophisticated electronics or a sophisticated slipper clutch to work at their optimum level – put them both together and they almost argue about who’s in charge.
So high performance machines won’t be running them?
Even MotoGP bikes, with all of their electronic wizardry, still run a slipper clutch. This is the best example of showing just how much of a perfect fall-back they are, as it makes life easy if you accidentally go down a gear extra or have an issue. It all depends on the electronics. If you have perfect corner specific corner entry electronics then you can have simple slipper clutch settings. Those with less sophisticated electronics, for example British Supersport, still get a lot more out of a better race slipper clutch. Over the last few years Kyle Ryde, Bradley Ray and the Gearlink Kawasaki team have done a lot of winning on them, alongside taking three championships in the Ducati Tri-Options Cup. If you’ve never ridden a bike with one, I’d encourage you to try one because it will make a massive difference to your riding.
A thing of beauty...
Simples! Even superstars like Fagan use slipper clutches.