overflow:hidden > overflow:visible

overflow:hidden > overflow:visible , works better, I use like this:

example {
 #menu ul li ul {

    background-color:#fe1c1c;
    width:85px;
    height:0px;
    opacity:0;
    box-shadow:1px 3px 10px #000000;
    border-radius:3px;
    z-index:1;
    -webkit-transition:all 0.5s ease;
    -moz-transition:all 0.6s ease;

}

 #menu ul li:hover ul  {

        overflow:visible;
    opacity:1;
    height:140px;
}