Quote:
Originally Posted by kkim
If our transmissions are DESIGNED to be shifted without the use of the clutch, can you explain why the manufactures' owners manuals say to use the clutch when shifting gears? Not doubting your word on research, but if what you've found pertains to all motorcycle transmissions and it is an inherent design to not use the clutch except from a stop, why is it they advise you to use the clutch between shifts?
I can shift up or down w/o the use of the clutch on a motorcycle but know if any of those shifts are not perfect, the wear and tear that missed shift can cause is not worth the ease of not pulling in the clutch lever, so I choose to use it for every shift.
|
Well said.
By using a clutch you disconnect the engine from the wheels, and therefore disconnect the torque produced by the engine and torque produced by the wheels (which is here from the kinetic energy of the moving object on these wheels). If these 2 torques were exactly the same, there would be no use for the clutch at all.
When clutch-less shifting, what you do by "rolling off" the gas is actually trying to synchronize the inertial torque and engine torque by lowering the rpm of the engine to the value which is expected in the next gear while bike is going at the given speed. But this increases the load on the synchronizers in the gearbox, and makes the shift "jerky", unless you make it perfect. As far as i know the synchros are some sort of frictional device, so the principle is same as with the clutch - something is rubbing against something else.
On the other hand, if you use the clutch, and sync the engine rpm with the gear rpm, your clutch is not suffering that much (keep in mind that it was made for what it does), and your syncros in the gearbox are suffering only the load of the inertial torque of the spinning shaft with the gears on it. This gives a nice and smooth shift with the use of the clutch.
Finally, you can be really bad to your clutch by doing poor job synchronizing engine and bike speed. This wears the clutch the most, if it must handle a large difference between the two.