Classification of bicovariant differential calculi over free orthogonal Hopf algebras

We show that if two Hopf algebras are monoidally equivalent, then their categories of bicovariant differential calculi are equivalent. We then classify, for $q\in {\mathbb{C}}^{\ast }$ not a root of unity, the finite dimensional bicovariant differential calculi over the Hopf algebra ${\mathcal{O}}_q(S{L}_2)$. Using a monoidal equivalence between free orthogonal Hopf algebras and ${\mathcal{O}}_q(S{L}_2)$ for a given $q$, this leads us to the classification of finite dimensional bicovariant differential calculi over free orthogonal Hopf algebras.