I just started putting together a Surly Steamroller fixie for riding on the trails and have been thinking of upgrading the road fork for a Surly 'cross model. However, I have heard that the 'cross fork will raise the head tube 12mm as it's configured a bit longer than the road fork (it's really configured for an entirely different frame.)

Anyway, what would raising the head tube 12mm really do to the handling of the bike? As I'm pulling together pieces to make this bike road-ready I'm finding myself more and more theorizing about equipment combinations without any real empirical evidence. It's a dangerous racket.

Thanks in advance,