Originally Posted by Sid Squid

It depends...mainly on the specific technique used.

A well executed clutchless change puts no more wear/stress/load on anything, and clearly puts less wear on the clutch, 'cos you didn't use it.

Upchanges:

There are several ways to do it, all essentially similar, differing only in detail and by the advantage they may give, (if you get it right that is).

Fastest change, used as if you're on a timed quarter, (ie drag racing):
Preload the lever firmly, roll out the throttle *just* enough for the dogs to be unloaded and the change to occur. With practice (ie lots of time on the strip), this can be a lightning fast change, the gear will go through very quickly, the time taken from on, to off, to on throttle is where the practice/skill lies, the further out you roll the throttle the longer it takes, the less you roll it out the harder the gear change is which takes longer too.
Downside: Wear, on everything, forks/grooves/pins/drum/dogs the lot, can be worth lots of time though, (relatively speaking, in a quick quarter), that said, as long as you don't make a constant habit of it, you won't break anything that quickly.

Lazy change, changing gear smoooooothly and unhurriedly just exactly like you would with the clutch, only...without:
Roll throttle out, lift gear lever, roll throttle back in again. If you do it right this change can be smoother than a cashmere codpiece, what you're looking for is for there to be no 'jerk' in the drive, bit of practice though and anyone can do it, the trick, (if there is one), is to only drop the throttle out to the point at which you would need it to be so that in the next gear you would neither be accelerating or decelerating from the speed at which you initiated the change, thus allows all the bits and pieces to be revolving at as near the same speed as possible thus they mesh together as imperceptibly as possible.
Downside: None, if you get it right, which isn't hard. Won't win you any drag races though.

Downchanges, Bit different this, similar principle to lazy change, that is: Smooooth.

First some things to know:
No matter what gear you're in, when the engine isn't running the speed of everything is nil, (yeah I know, blindingly bloody obvious, but hold that thought), that is; all the same speed. Using convenient figures, say that at 10,000rpm 1st gear makes the output shaft of the gearbox revolve at 1000rpm, 2nd 2000rpm, 3rd 3000rpm etc. Knowing this it can easily be seen that the faster the engine speed is, the further apart, relatively speaking, the speeds of the gearbox parts are. At 10,000rpm the relative speeds are 1000rpm apart, at 5000rpm 500rpm apart, at tickover (say 1000rpm, easy numbers see? I like that), the relative speeds only differ by 100rpm.

A smooth change occurs when the various bits that need to mesh are revolving at as similar speeds as is possible, in practice the slowest that you can run the engine is tickover, if you were to change down clutchless at as close to tickover as possible the relative parts would be as best speed matched as is possible. If you were to add the slightest smidgeon of throttle just as you go to change, this would unload the 'box and make the change easier, also it would speed the drive into the gearbox up a bit, such that it would be running at the slightly higher speed that the lower gear would demand to run at the same speed, just as in the the lazy change above.
Downside: Not easy to get right, and basically no advantage anyway, save for a useful technique to have when the clutch cable breaks at an inconvenient time, I have done several hundred miles like this, getting neutral while still rolling makes all the difference.

Originally Posted by Baph

Can't hurt to try new things :)