Angular 2 Two way binding with [disabled]

I have an input with [disabled] depending upon the ngModel of another input. Initially [disabled] is working properly but not when we change the dependant input value, the [disabled] property is not working. How to apply two binding on [disabled] property?

Following is the code snippet.

<select [ngModel]="isDisabled" (ngModelChange)="isDisabled=$event">
<option value="0">Disabled</option>
<option value="0">Enabled</option>
</select>

This model isDisabled is changed correctly. I could see the value change like this in template {{isDisabled}}. But not reflected in the [disabled] property of the select box.

<select [ngModel]="userInput" [disabled]="isDisabled">
<option value="test">Test</option>
</select>