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Here you can Sed posuere consectetur est at lobortis. Donec ullamcorper nulla non metus auctor fringilla. Maecenas sed diam eget risus varius blandit sit amet non magna. Donec id elit non mi porta gravida at eget metus. Praesent commodo cursus magna, vel scelerisque nisl consectetur et.

            
              <div id="wrap">
  <svg xmlns:svg="http://www.w3.org/2000/svg" xmlns="http://www.w3.org/2000/svg" width="800" height="500" id="svg3906" version="1.1" viewBox="0 0 800 500">
  <defs id="defs3908">
    <filter color-interpolation-filters="sRGB" id="filter4001" x="-0.08" width="1.15" y="-0.39" height="1.77">
      <feGaussianBlur stdDeviation="18.06" id="feGaussianBlur4003"/>
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      <rect id="rect12849" width="562.5" height="112.5" x="145.27" y="425.5" style="fill:#fffcfc;filter:url(#filter4001)"/>
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    <g id="meterParent" mask="url(#mask12847)" transform="translate(196.23395,-28)">
      <g id="meter">
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        <rect y="475.5" x="564.33" height="12.5" width="2" id="use3049" style="fill-opacity:0.87;fill:#000"/>
        <rect y="463" x="627.16" height="25" width="2" id="use3051" style="fill-opacity:0.87;fill:#000"/>
        <rect y="475.5" x="689.99" height="12.5" width="2" id="use3053" style="fill-opacity:0.87;fill:#000"/>
        <rect y="475.5" x="752.82" height="12.5" width="2" id="use3055" style="fill-opacity:0.87;fill:#000"/>
        <rect y="475.5" x="815.66" height="12.5" width="2" id="use3057" style="fill-opacity:0.87;fill:#000"/>
        <rect y="475.5" x="878.49" height="12.5" width="2" id="use3059" style="fill-opacity:0.87;fill:#000"/>
      </g>
    </g>
  </g>
  <g id="layer3">
    <g id="tWheelset" transform="translate(510,220)">
      <g id="wheelset">
        <g id="wheel" transform="translate(-150,-300)">
          <path id="path5301" d="m150 100 0 400" style="fill:none;stroke-width:4;stroke:#000"/>
          <path d="M350 300C350 410.46 260.46 500 150 500 39.54 500-50 410.46-50 300-50 189.54 39.54 100 150 100c110.46 0 200 89.54 200 200z" id="path3778" style="fill-opacity:0.85;fill:#dbdbdb;stroke-opacity:0.3;stroke:#040404"/>
          <path id="path3858" d="M262.5 300C262.5 237.87 212.13 187.5 150 187.5 87.87 187.5 37.5 237.87 37.5 300l225 0z" style="fill-opacity:0.85;fill:#f60;stroke:#000"/>
          <path id="path3849" d="m262.5 300-225 0c0 62.13 50.37 112.5 112.5 112.5 62.13 0 112.5-50.37 112.5-112.5z" style="fill-opacity:0.87;fill:#fffcfc;stroke:#000"/>
        </g>
        <circle d="M 40,0 C 40,22.09139 22.09139,40 0,40 -22.09139,40 -40,22.09139 -40,0 c 0,-22.09139 17.90861,-40 40,-40 22.09139,0 40,17.90861 40,40 z" r="40" cy="0" cx="0" id="sprocket" style="fill:none;opacity:0.5;stroke-width:15;stroke:#ddd"/>
      </g>
    </g>
  </g>
  <g id="layer5">
    <path d="m-120 10 40 0c24.93 0 45 20.07 45 45 0 24.93-20.07 45-45 45l-40 0c-24.93 0-45-20.07-45-45 0-24.93 20.07-45 45-45z" id="chain" style="fill:none;stroke-dasharray:15;stroke-linecap:round;stroke-linejoin:bevel;stroke-width:6;stroke:#000"/>
  </g>
  <g id="layer2">
    <g id="tCrankset" transform="translate(210,220)">
      <g id="crankset">
        <circle id="chainring" cx="0" cy="0" r="70" style="fill:none;opacity:0.5;stroke-width:15;stroke:#ddd"/>
        <g id="crankarm" stroke-width="5">
          <path d="M10 0A10 10 0 1 1-10 0 10 10 0 1 1 10 0z" id="path12042" style="fill-opacity:0.55;fill:#f9f9f9;opacity:0.98;stroke-width:5;stroke:#000"/>
          <path d="m-110 0a10 10 0 1 1-20 0 10 10 0 1 1 20 0z" id="path12046" style="fill-opacity:0.55;fill:#f9f9f9;opacity:0.98;stroke-width:5;stroke:#000"/>
          <path id="path12048" d="M-110 0-10 0" style="fill:none;stroke-width:5;stroke:#000"/>
        </g>
      </g>
    </g>
  </g>
  <g id="layer6">
    <path id="shiftFront" d="m75.2 379.86 0-18.99 16.44 9.49z" transform="translate(144.79695,119.13139)"/>
    <path transform="matrix(-1,0,0,1,275.20305,119.13139)" d="m75.2 379.86 0-18.99 16.44 9.49z" id="shiftFrontDown"/>
    <path transform="translate(444.79695,119.13139)" d="m75.2 379.86 0-18.99 16.44 9.49z" id="shiftBackUp"/>
    <path id="shiftBackDown" d="m75.2 379.86 0-18.99 16.44 9.49z" transform="matrix(-1,0,0,1,575.20305,119.13139)"/>
  </g>
</svg>
</div>
            
          
!
            
              body {
  background: #f7f4ee;
  display: flex;
  flex-direction: row;
  justify-content: center;
  align-items: center;

  height: 100vh;
}

#wrap {
  width: 100%;
  max-width: 700px;
  margin: 0 auto;
}

svg {
  width: 100%;
  height: 100%;
}

#layer6 path {
  cursor: pointer;
  fill: black;
  stroke-width: 0;
}

#layer6 path:hover {
  fill: #f60;
}

            
          
!
            
              window.onload = function () {
	
  (function(){ 

  	// Representation of the drivetrain modules
		var crankset = Crankset(); 
		var chain = Chain ();
		var wheel = Wheel();

		crankset.init(1);
		chain.init( crankset.getChainspeed() );
		wheel.init( crankset.getChainspeed() );

		// Update/control functions. Perhaps this is just a overcomplicated way to
		// define event handlers 
		var shiftFrontSprocket = function ( d ) {
			var r = crankset.chainring.getRadius ( ) + d;
			if ( r <= 0 || r > 200 ) return;
			crankset.chainring.setRadius ( r );

			chain.updateFrontSprocket( r );
			wheel.update ( crankset.getChainspeed() );
			meter.update ( Math.PI / wheel.getAngVel() );
		};

		var shiftBackSprocket = function ( d ) {
			var r = wheel.sprocket.getRadius ( ) + d;
			if ( r <= 0 || r > 200 ) return;
			wheel.sprocket.setRadius ( r );

			chain.updateBackSprocket( r );
			wheel.update ( crankset.getChainspeed() );
			meter.update ( Math.PI / wheel.getAngVel() );
		};

		Shifter ( 'shiftFront', shiftFrontSprocket, 15 );
		Shifter ( 'shiftFrontDown', shiftFrontSprocket, -15 );
		Shifter ( 'shiftBackUp', shiftBackSprocket, 10 );
		Shifter ( 'shiftBackDown', shiftBackSprocket, -10 );

		// The terrain
		var meter = Meter();
		// How long should the pan take? Just as long as it takes for the wheel to do a half loop,
		// also PI/ang_vel
		meter.init( Math.PI / wheel.getAngVel() );
	})();
}

var Meter = function() {
	var sprite = document.getElementById( 'meter' );
	var tween = null;
	var orig_dur;
	
	return {
		init: function ( dur ) {
			orig_dur = dur;

			// Start pan:
			tween = new TweenMax( sprite, dur, {
				x: Math.PI*200, 
				ease: 'Linear.easeNone', 
				repeat: -1
			});	
		},
		update: function ( dur ) {
			tween.timeScale ( orig_dur / dur );
		}
	};
};

var Crankset = function(  ){
	var sprite = document.getElementById( 'crankset' );
	var tween = null;
	var ang_vel; // Constant after initialization
	var chainspeed;

	// As a reminder, to show what's the difference with the modular pattern
	// here a normal literal object: observe the use of 'this'
	var chainring = {
		sprite: document.getElementById( 'chainring' ),
		setRadius: function ( r ) {
			this.sprite.setAttribute('r', r);
			chainspeed = r * ang_vel;
		},
		getRadius: function ( ) {
			return parseInt(this.sprite.getAttribute('r'));
		}
	}; 

	return {
		chainring: chainring,
		init: function ( w ) {
			ang_vel = w;
			chainspeed = ang_vel * chainring.getRadius();
			tween = new TweenMax(sprite, 2*Math.PI/w, {
				rotation: -360, 
				ease: 'Linear.easeNone', 
				repeat: -1
			});			
		},
		getChainspeed: function () {
			return chainspeed;
		}
	}
};

var Chain = function ( ) {
	var sprite = document.getElementById( 'chain' );

	// Deriving the chain from the svg is hard because getClientRect and getBBox
	// do not give the result in svg screen coordinates. (How about snap's getBBox()?)
	// (Or how about extracting the coordinates from the transform property?)
	// Just type in the numbers then

	var sprocket0 = { m: { x: 210, y: 220}, r: 70};
	var sprocket1 = { m: { x: 510, y: 220}, r: 40};

	// Define the shape of the chain by calculating the 2 lines tangent to both sprockets
	var tangentLines = [];

	calcTangents = function () {
		// Calculate angle between the line through the centers of the circles and 1 of the 2 lines tangent to both circles
		var dx = sprocket0.m.x-sprocket1.m.x;
		var dy = sprocket0.m.y-sprocket1.m.y;
		var d = Math.sqrt(dx*dx + dy*dy);
		var angle = Math.asin ( (sprocket0.r - sprocket1.r) / d );

		// Now do some math to get the actual tangent lines
		angle -= Math.PI/2;
		var ca = Math.cos( angle );
		var sa = Math.sin( angle );

		tangentLines[0] =[
			sprocket1.m.x + sprocket1.r * ca,
			sprocket1.m.y + sprocket1.r * sa,
			sprocket0.m.x + sprocket0.r * ca,
			sprocket0.m.y + sprocket0.r * sa,
		];
		tangentLines[1] = [
			sprocket0.m.x + sprocket0.r * ca,
			sprocket0.m.y - sprocket0.r * sa,
			sprocket1.m.x + sprocket1.r * ca,
			sprocket1.m.y - sprocket1.r * sa,
		];
 	};
	
	/*
	 * Draw the convex hull around the two circles
	 */
	getChainPathData = function ( ) {
		var sweep = sprocket1.r > sprocket0.r ? 1 : 0;

		var d = "M" + tangentLines[0][0] + " " + tangentLines[0][1] + " L" + tangentLines[0][2] + " " + tangentLines[0][3];
		// add arc sprocket1
		d += " A " + sprocket0.r + " " + sprocket0.r + ", 0, " + parseInt(1-sweep) + ", 0, " + tangentLines[1][0] + " " + tangentLines[1][1]
		d += " L " + tangentLines[1][2] + " " + tangentLines[1][3];
		// add arc voorblad
		d += " A " + sprocket1.r + " " + sprocket1.r + ", 0, " + sweep + ", 0, " + tangentLines[0][0] + " " + tangentLines[0][1];

		return d;
	};
	var update = function() {
		calcTangents();

		// draw new calculated chain shape
		sprite.setAttribute('d', getChainPathData() );	

		// timescale tween
		tween.timeScale(sprocket0.r/sprocket0.orig_r);
		
	};

	return {
		init: function( speed ) {
			// remember original radius, to alter tween afterwards
			sprocket0.orig_r = sprocket0.r; 

			tween = new TweenMax( sprite, 30/speed, {
				'strokeDashoffset': -30, 
				ease: 'Linear.easeNone', 
				repeat: -1
			});			
			update();
		},
		updateFrontSprocket: function ( r ) {
			sprocket0.r = r;
			update();
		},
		updateBackSprocket: function ( r ) {
			sprocket1.r = r;
			update();
		}
	}
}

var Wheel = function ( ) {
	var sprite = document.getElementById( 'wheelset' );
	var tween = null;
	var ang_vel,
			orig_ang_vel;

	var sprocket = {
		sprite: document.getElementById( 'sprocket' ),
		setRadius: function ( r ) {
			this.sprite.setAttribute('r', r);
		},
		getRadius: function ( ) {
			return parseInt(this.sprite.getAttribute('r'));
		}
	}; 

	return {
		sprocket: sprocket,
		init: function ( chainspeed ) {

 			ang_vel = chainspeed / sprocket.getRadius();
			tween = new TweenMax(sprite, 2*Math.PI/ang_vel, {
				rotation: -360, 
				ease: 'Linear.easeNone', 
				repeat: -1
			});			

			orig_ang_vel = ang_vel;
		},
		update: function( chainspeed ) {
			// timescale tween
 			ang_vel = chainspeed / sprocket.getRadius();
			tween.timeScale(ang_vel/orig_ang_vel);
		},
		getAngVel: function() {
			return ang_vel;
		}
	}
};	

var Shifter = function( spriteId, callback, d ) {
	var sprite = document.getElementById ( spriteId );

	sprite.onclick = function() {
		callback( d );
	};
};
            
          
!
999px
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