  Steinhaus conjectured that every closed oriented $C^1$-curve has a pair of
anti-parallel tangents. Porter disproved the conjecture by showing that there
exist curves with no anti-parallel tangents. Colin Adams rised the question of
whether there exists a nontrivial knot in $\R^3$ which has no parallel or
antiparallel tangents. The main result of this paper solves this problem,
showing that any (smooth or polygonal) link $L$ in $\R^3$ is isotopic to a
smooth link $\hat L$ which has no parallel or antiparallel tangents.
