var bikeCounter = 1;
var bikeLimit = 2;
var helmCounter = 1;
var helmLimit = 2;
var itemCounter = 1;
var itemLimit = 6;

function bikeInput(divName){
     if (bikeCounter == bikelimit)  {
          alert("You have reached the limit of adding " + bikeCounter + " bikes");
     }
     else {
          var newdiv = document.createElement('div');
          newdiv.innerHTML = "<tr><td align=\"right\">Bike " + (bikeCounter + 1) + ":</td><td align=\"left\"><input type='text' name=\"bike" + (bikeCounter + 1) + "\"></td></tr>";
          document.getElementById(divName).appendChild(newdiv);
          bikeCounter++;
     }
}