Googling produces three hits. Your bicycling reference, a business news item that is a mite too insider for my poor little economically challenged brain http://www.fiorentina2000.net/news/0600/19k.htm (Scroll down the paragraph starting with "Bayer Leverkusen") and some bbs2.fanforum thang that I can't get in to but which includes "... fears, they are not fearless. She was tender to Michael, friend to Liz and Max, combactive when she needed to be. We know that these writers make any couple a ... "

The Renaissance of the Age of Ink Horn Terms is upon us.

But more to the point, it sounds to me like it is intended to be a portmanteau word made up of combative and active and, as such, to mean combative, but with some intent to the combativeness beyond a simple desire to get into scraps.