void function calc(gear_form, bAnalyze)
{
var front = parseFloat(gear_form.chainwheel.value);
var rear = parseFloat(gear_form.freewheel.value);
var wheelsize = parseFloat(gear_form.wheelsize.value);
var gear_ratio = front / rear;
var gear_size = ( front / rear ) * wheelsize;
gear_ratio = parseInt((gear_ratio + .005) * 100) / 100; // round to 2 decimal places
gear_size = parseInt((gear_size + .005) * 100) / 100; // round to 2 decimal places
gear_form.gearsize.value = gear_size;
gear_form.gearratio.value = gear_ratio;
gear_form.gearsize.disabled = true;
gear_form.gearratio.disabled = true;
if ( bAnalyze )
{
analyze_gear(gear_ratio);
}
}
function analyze_gear(gear_ratio)
{
var sMsg = "";
if ( gear_ratio > 2.9 )
{
sMsg = "This is a high gear. It provides higher speeds, but slower acceleration.\n";
sMsg += "This gear ratio is ideal for downhill bmx tracks or some trail riding.";
}
else if ( gear_ratio < 2.65 && gear_ratio > 2.5 )
{
sMsg = "This is a low gear. It provides quick acceleration but slower speeds.\n";
sMsg += "This gear ratio is ideal for street riding or tight, technical bmx tracks.";
}
else if ( gear_ratio <= 2.5 )
{
sMsg = "This is a very low gear. It allows great acceleration but not much speed.\n";
sMsg += "This gear ratio is ideal for flatland or technical mini-ramp riding.";
}
else
{
sMsg = "This is a normal gear. It allows a balanced mix of acceleration and speed.\n";
sMsg += "This gear ratio is ideal for most bmx tracks, dirt jumping, street, and most ramp riding.";
}
var sText = "";
var sURL = "";
var sName = "GearInfoWin";
var lWidth = 500;
var lHeight = 150;
var lLeft = (screen.availWidth / 2) - (lWidth / 2);
var lTop = (screen.availHeight / 2) - (lHeight / 2);
var sFeatures = "directories=false,menubar=false,resizable=false,scrollbars=false,status=false,toolbar=false,";
sFeatures += "height=" + lHeight + ",width=" + lWidth + ",left=" + lLeft + ",top=" + lTop;
var oNewWin = window.open(sURL,sName,sFeatures);
sText += "";
sText += "";
sText += "Dan's Gear Information";
sText += "";
sText += "";
sText += "";
sText += "";
sText += " | ";
sText += "" + sMsg + " | ";
sText += "
";
sText += "
";
sText += "";
sText += "";
oNewWin.document.writeln(sText);
//alert(sMsg);
}