In reply to VS4b:
Personally I'd replace the carbon forks as a precaution, but checking the frame visually for any paint distortion/rippling and cracks etc should be enough, and 17mph 'probably' won't have done much, anyway.
I understand that ( for road bikes at least) carbon frames and forks are plenty strong enough when loaded how they're designed to be, but crashes and knocks can load them in a way which creates weakness, so they can fail.
Well made MTB carbon frames etc are plenty tough, but with road bikes being more delicate, and carbon tending to fail without warning (when it does fail), I'd always have in the back of my mind that it might have been weakened, if I wasn't able to find out for sure with an Xray or something like that.
Post edited at 21:38