We had a pretty epic chase in a game I was in once, but we didn't use any existing rules really, we just did what seemed logical. I was chasing something whose base speed was higher than mine, but he had to slow down to go around corners and I'd catch up a little, then I'd hit the corner and slow down too and he'd get a little ahead again.... eventually during one of the closer moments I chucked a dagger at him and crit. Apparently, even though your arms and legs tend to wave around a lot when running, your head stays pretty steady! Though that doesn't really hep you huh? I guess my advice would be to ad-hoc your own rules when the situation presents itself.