In fact, for any positive $\epsilon < 1/12$ the inequality given in the $abc$-conjecture $$ rad(abc) > c_{\epsilon}c^{1-\epsilon} $$ with an explicit value of $c_{\epsilon}>0$ yields an explicit upper bound on $x^p, y^q, z^r$ in any counterexample to Beal's conjecture. By the $abc$-conjecture, there are only finitely many such $(a,b,c)$-triples.