Reader Zach sent in the follow description and pictures of a homemade chain tensioner he developed.
Here is my home made single speed chain tensioner for bikes with horizontal dropouts (not track ends) I’m a big guy, 245, and felt i needed a little more security against my hard sprints. probably not doable for everyone, i just happen to work in a machine shop so this was a fairly simple task.
Nice job I would say. The design reminds me of the ones I have been looking at on EBAY. I am thinking of buying a new set for my 2008 Redline 925 since the ones that came with the bike are plastic.