There is all torsion at the pivot.
BTW: construction like that can well made to be stable. Simplest approach: thickening the arms.
Then: use CFK.
Like here - latest successor of my bike , the Evo-R which is one of the really light, stiff and fast machines:
And here my 1st test with wood (spruce). Noticeable improvement, but torsion remains. Which tells me how large the effect of torion in the arms really is.
