Since the maximum avatar size is now 120x120, my personal favorite for avatar sizes, I think we should also have it display 120x120 in postbit. This can simply be done so bye editing the Theme Name > Templates > Postbit > Postbit_Avatar and repplacing.
with
Code:
<a href="{$post['profilelink_plain']}"><img src="{$post['avatar']}" alt="" {$avatar_width_height} /></a>with
Code:
<a href="{$post['profilelink_plain']}"><img src="{$post['avatar']}" alt="" width="120" height="120 "/></a>