What is Rotational Inertia?
Inertia is a "resistance to a change of motion". The more inertia an object has, the less it responds to being accelerated or pushed. You are no doubt aware that, all other things being equal, that a heavier bike will accelerate down a drag strip slower than a lighter bike. The more weight or mass in an object, the less it responds to being accelerated or pushed.
Rotational inertia is a resistance to change of rotation. The more rotational inertia designed into an object, the less it responds to being spun up. An engines flywheel is designed to use this principle to slow or accelerate an engines throttle response depending both on its weight and how far out from the center the weight is placed. The further out from the center the weight of a spinning object is placed the greater inertia it creates. This is particularly important on Supersport bikes as the FIM Supersport rules prevent modifications to the crank. You cannot then modify the crank for quicker throttle response to make up for a clutch that adds rotational inertia.
It is quite possible to have two different, in this case, clutches, weighing the same but with one giving significantly more rotational inertia than the other—for a swift demonstration fill a bucket with some water; attach a 2 metre rope, grab hold of it and spin it round. Do it first with both 2 metres, and then try it with 1 metre. The shorter length requires less effort and less speed, it has less rotational inertia, that's why we prefer to keep the heavier spring materials near the center of our clutch.
Yoyodyne Kawasaki 250cc Slippers
Will my slipper clutch require a lot of maintenance?
No, but if you abuse it then it will require some. For normal use the plate wear is negligible. In extreme situations, as an example if you never use the clutch lever for downshifts and you are racing on the GP circuit at Donington with three consecutive hairpins then it doesn't seem unreasonable to assume clutch and plate wear will be accelerated. If however you are working the clutch lever as normal, just allowing the Clutch to help maintain grip, then plate wear should be near normal. The mechanism itself and the condition of the plates should be checked more often if it subjected to regular extreme use.
Can I use my bikes standard clutch plate packs?
Yes, in most cases they are the best option, but on rare occasions, and for specific uses, there are better solutions, just have a look in our race setup page for more info.
Will the clutch bolt straight in; will I have to modify anything?
All Slipper clutches we sale will fit straight on with no modification, each clutch comes with proper instructions, the only special tool you will need is your bike manufacturers standard clutch holding tool. Any competent mechanic familiar with the type of bike will have no trouble fitting the clutch, just make sure they read the instructions as each clutch has its own idiosyncrasies.
Sigma Yamaha R-3 320cc Slippers
Do I need to change my down shifts or can I ignore the clutch lever?
The clutch is designed to stop rear wheel hopping under rapid deceleration, if you decide to ignore the clutch lever the clutch will do the work for you and will use the clutch friction plates to do the work, wearing the plates quicker if you do it all the time. If you ride normally, using the clutch lever for downshifts, the work level for the clutch is reduced and less wear occurs. Most of the time it's a case of just go out and ride.