[jQuery] UI slider execute function on change or slide

Hi,
I want to make the UI slider to set a font-size to a .cica class. The
setfontsize variable works but I can not succeed to make the slider
change the value on slide.

Here is the function

$('#sizer').slider({
slide: function(event, ui) {
var setfontsize = $('#sizer:selected').text();
$('.cica').css("font-size", setfontsize + "px");
}

Here is the markup

<form action="#">
<!-- Slider -->
<fieldset>
<select name="speed" id="speed">
<option value="10">10</option>
<option value="15">15</option>
<option value="21" selected="selected">21</option>
<option value="30">30</option>
<option value="40">40</option>
</select>
</fieldset>
</form>

Thank you.