I have a 15/24 pikeman alt that I play as support mostly, sitting behind infantry and thrusting at targets of opportunity. I wear light mail (mail shirt) and use my athletics, and jumps to generate speed bonus.
I find overall its very effective, and I get a very nice amount of kills and even more assists from stunning people to set them up for a killshot by some str juicehead. The 8 athletics and light armour lets me rove behind the line easily, switching up targets, and backing out of trouble if someone rushes me.
The other style of being more of a "duelist" pikeman, wearing plate and defending yourself with fancy spin moves, not worrying about being on the frontline would definitely be more effective with a STR build.