I went on a group ride earlier with a new club that I haven't ridden with... I rolled with the guys that race doing the "hard" route. I/We were doing 30 (flats/false flats) for most of the time.

We hit a hard hill (23% grade - unsure of length) and my legs just went completely jello/seriously in pain.... I had to bow out and ride the route of shame home. T'was not a good day for me.