I use to do, what was classed as extreme sports and found that trying to obtain the 'correct' insurance was a constant problem, especially if it involved land-owner's and personal liabilities, including club or private membership.
You are quite right in saying "I don't think it's as simple as that.", because if you do not know what you are doing, then it can lead into a minefield of possible future problems.
What I would suggest is that you contact a local insurance broker who undertake sport insurance for advice, or even a major cycling magazine. You might even get some advice from the Sports Council click here