ReactJS onChange function

Where am I going wrong with my onChange function? I want to be able to type in my textbox, but I keep getting the following console error when I recompile:

**Uncaught TypeError: Cannot read property 'value' of undefined**

See code below:

export default React.createClass({

  handleChange: function() {
    this.props.onUserInput(
        this.refs.name.value    
    )
  },

  render() {
    return (
      <div>
        <div>{this.props.children}</div>
        <Well style={style.well}>
          <div style={style.userContent}>

            <input style={style.userDetails} 
                   id ="userName" 
                   type="text" 
                   onChange={this.handleChange()} 
                   value ={name} />

              <Button bsStyle="primary">Update</Button>
          </div>
        </Well>         
      </div>
    );
  }
});