For the most part, combatants in the SSG opt either to go with transitional armour of the late 14th and very early 15th century, or sporting equipment. Really, our range goes from 1350 - 1450 or so.
One of the underappreciated things about the surviving treatises is that they often depict details of arming clothing, footwear, and armour not shown anywhere else. Sometimes these are fanciful, figments of what equipment "could be" like, but sometimes as is the case of the Talhoffer 1459 manuscript, we get much more.
Dr. Price commissioned this harness from the Ukrainian artisans working under the trade name "Art of Steel," after a prolonged period of research and consultation back and forth. Intended for a future book on poleaxe fighting, equestrian work and maybe the occasional feat of arms, the harness includes many fine details.
A harness like this one isn't fast to develop, however. This one took more than two years of research and consultations.
Most combatants prefer to fight in transitional armour; the SCA favors it, as does the ACL/IMCF, not only because there were some interesting tourney forms during that time, but also because the blend of mobility and personal expression is almost limitless. Check out the SSG Arms & Armour members page for more on how to source, work with and acquire a harness of your own, whether it is a simple transitional or a more poleaxe-not-quite-proof-but-oh-well harness like this.