NightWing wrote:
Double clutching is needed on transmissions that aren't synchronized between gears, or those that have bad synchronizers.
I haven't driven a manual Vespa since 1967, but I remember that the bike can be shifted in motion by working the throttle against a pre-loaded shifting grip and nothing would grind. I had to use that technique a few times when I broke a clutch cable and was miles from home. I could even start from a stop like that. It was abrubpt and quite a jolt but it could be done. Vespas are amazing.
I haven't driven a manual Vespa since 1967, but I remember that the bike can be shifted in motion by working the throttle against a pre-loaded shifting grip and nothing would grind. I had to use that technique a few times when I broke a clutch cable and was miles from home. I could even start from a stop like that. It was abrubpt and quite a jolt but it could be done. Vespas are amazing.
As I'm sure you know, Nightwing, even in cars will full synchro-mesh gearboxes you can change gears quite seamlessly without the clutch as long as you correctly match RPM in the appropriate gear for the given vehicle speed. It's easier to do upshifting than down, of course.