// If you want to use image link

$image_variable = wp_get_attachment_image_src( get_post_thumbnail_id( $post->ID ), 'large' ); echo $image_variable[0];


// If you want to use your custom size

$image_variable = wp_get_attachment_image_src( get_post_thumbnail_id( $post->ID ), 'post-image' ); echo $image_variable[0];



?>