When the BF search is not working (like, always), you can search as frequently as you want with Google's "site search."

In the Google search box, just enter: site:www.bikeforums.net how fast can you sprint

and all the useless threads you could want will appear in the results. Here is a sample BF search result. The results will usually link to archived threads, but there is a link in them that will allow you to go to the real BF thread and reply or whatever. Here's the link in an archived page:

This is an archived thread, you can find the full version of this thread, with images, links and more content here.

If you have the Google Toolbar installed, you can enter your search string there, and hit the site search button: . This will create the "site:" search string for you.

Enjoy!