function calc_mountenbike ()
			{
				steplength = document.mountenbike.steplength.value;
				if (isNaN (steplength.replace (",", ".")) == true)
				{
					document.mountenbike.steplength.value = 0;
					steplength = 0;
					alert ('Der Eintrag in der Spalte Schritthöhe hat ein ungültiges Format!');
				}		
				document.mountenbike.sizeinzoll.value = (Math.round (steplength * 0.226));
				document.mountenbike.sizeincm.value = (Math.round (document.mountenbike.sizeinzoll.value * 2.56));
			}
			function calc_fullsuspension ()
			{
				steplength = document.fullsuspension.steplength.value;
				if (isNaN (steplength.replace (",", ".")) == true)
				{
					document.fullsuspension.steplength.value = 0;
					steplength = 0;
					alert ('Der Eintrag in der Spalte Schritthöhe hat ein ungültiges Format!');
				}		
				document.fullsuspension.sizeinzoll.value = (Math.round (steplength * 0.225));
				document.fullsuspension.sizeincm.value = (Math.round (document.fullsuspension.sizeinzoll.value * 2.56));
			}
			function calc_racingbike ()
			{
				steplength = document.racingbike.steplength.value;
				if (isNaN (steplength.replace (",", ".")) == true)
				{
					document.racingbike.steplength.value = 0;
					steplength = 0;
					alert ('Der Eintrag in der Spalte Schritthöhe hat ein ungültiges Format!');
				}		
				document.racingbike.sizeracingbike.value = (Math.round (steplength * 0.665));
				document.racingbike.sizetriathlonbike.value = eval (document.racingbike.sizeracingbike.value) - 4.25;
			}
			function calc_sporttouring ()
			{
				steplength = document.sporttouring.steplength.value;
				if (isNaN (steplength.replace (",", ".")) == true)
				{
					document.sporttouring.steplength.value = 0;
					steplength = 0;
					alert ('Der Eintrag in der Spalte Schritthöhe hat ein ungültiges Format!');
				}		
				document.sporttouring.sizeinzoll.value = Math.round (steplength * 0.24);
				document.sporttouring.sizeincm.value = Math.round (steplength * 0.61);
			}
			function calc_trekkingbike ()
			{
				steplength = document.trekkingbike.steplength.value;
				if (isNaN (steplength.replace (",", ".")) == true)
				{
					document.trekkingbike.steplength.value = 0;
					steplength = 0;
					alert ('Der Eintrag in der Spalte Schritthöhe hat ein ungültiges Format!');
				}		
				document.trekkingbike.sizeinzoll.value = Math.round (steplength * 0.259);
				document.trekkingbike.sizeincm.value = Math.round (steplength * 0.66);
			}