I believe I've written about this in at least 15 threads on this forum, but probably never
in this section.
Yeah, it's the clutch.
Easy to fix, too.
Pull both brakes in, hard, open up the throttle (a lot), and slooowly let got of the
brakes, just enough so the bike will slowly start creeping forward. Let it go forward
a foot or two, stop, repeat 2-3 times.
Shuddering gone.