Good post.
Just to expand on it a little bit, if the throttle is adjusted so that the engine is neither pushing the bike nor is it braking the bike, the transmission will slip out of any gear effortlessly. Going into the next gear (on an up shift) will be almost as effortless because only the engine, not the entire bike, has to accelerate slightly to match the chassis speed.
Think of it as trying to stick a stick into a picket fence while traveling next to that fence in a car, and assuming the fence is moving but at a different speed than the vehicle: a clutch uncouples the fence so that it is far easier to bring the fence up to or down to the vehicle's speed as the stick goes in. Backing off the throttle allows the vehicle to sort of 'float' next to the moving fence and approximate the fence's speed.
It is easy to try- when moving along at a steady speed, load the shifter as if you were shifting normally with the clutch. Because the gears are loaded by the power going from the engine to the bike's driveshaft, the shifter lever won't move. Gently back off the throttle and when the engine's deceleration matches the bike's deceleration, the lever will suddenly become free and slide out of the current gear- and move into the next (upper) gear pretty smoothly. If done right, a passenger cannot even tell if you are using the clutch or not. As already mentioned, it does not work nearly as well when downshifting because the engine must be accelerated to match the speed of the vehicle while going into the next gear (lower gear).
Someone recently posted on the other forum about having ridden motorcycles for many years and never having used the clutch when up shifting. He was properly chastised of course and may have learned his lesson (that posting such things will get you slapped on the Internet) but of course he was exactly correct too- up shifting without the clutch is harmless provided it is done correctly and gently. A clutch goes a long way to making sloppy or careless shifting go smoothly; it can never hurt to use a clutch but it does take some care and finesse to up shift without it. I just do not recommend down shifting without the clutch as there is no way to make that really graceful from the transmission’s point of view.
Brian
Brian, et al... maybe a noob questions... I read this somewhere before but never found the answer. How is this possible? And why would one shift without disengaging the clutch?
All the clutch does when shifting between gears is "unload" the transmission, which is a fancy way of saying the gears aren't mashed together by engine power. You can do the same thing with the throttle; blip the throttle "off" for a moment and it will unload the trans. Usually the rider "preloads" the shifter by putting about half-normal upwards pressure on it, and the blip of the throttle makes the shift. It's not really bad for the trans; there are riders who do it pretty much every shift, and their transmissions don't seem to break any more often. I think you'd be hard-pressed to find a racer that uses the clutch for upshifts. You can do a similar thing for downshifts, but it's not the same...downshifting without the clutch can cause problems. There are racers who do that as well, but their transmissions have to be rebuilt between races.
As to why...faster shifts and laziness.
