I'm using Safari 2.0 under Mac OS X 10.4 (Tiger). For any forum in RSS that I subscribe to, only 15 total posts appear. Any idea why?

For example, here's the RSS feed for Travel Technology: feed://www.flyertalk.com/forum/external.php?type=rss2&forumids=169

When I click on the above link, only 15 total posts show up. Same thing with other forums.