So I spent some time today trying to figure out how to set bbpress forum to have no side bar and full page width. After some looking I finally got it working with the theme Twenty Twelve doing the following:
1. Copy wp-content/themes/twentytwelve/page-templates/full-width.php to wp-content/themes/twentytwelve/bbpress.php
2. Edit wp-content/themes/twentytwelve/bbpress.php to add style 100% like this:` div id=”primary” class=”site-content” style=”width:100%” `
I found this solution here:
Thanks to serpini for posting it.