Got excited when I first read this thread's title..."Hill Speed"...I was thinking downhill...drats...well anyway, will share my thoughts.. Top speed downhill today on the Blue Ridge Brutal (75miler) was 54.2mph....wow, that was fun.

On the up hills, however, I find it helpful to alternate standing/sitting and concentrating on relaxing the quads and pulling more with the calves...all changes to muscle groups seem to help me.