In open content communities like Wikipedia and StackOverflow and in open source software projects, a small proportion of users produce a majority of the content and take on much of the required community maintenance work. Understanding this class of users is crucial to creating and sustaining healthy communities. We carried out a mixed-method study of core contributors to the Cyclopath geographic wiki and bicycle routing web site. We present our findings and organize our discussion using concepts from activity theory. We found that the Cyclopath core contributors aren't the dedicated cyclists and that the characteristics of the community shape the site, the rules, and the tools for contributing. Additionally, we found that numerous aspects about the surrounding ecology of related systems and communities may help to shape how the site functions and views itself. We draw implications for future research and design from these findings.