[nradov]

When going around a blind corner you have to reduce speed enough to be able to stop quickly or avoid any obstacles. This is just basic defensive driving. It's not about bikes; deer, fallen tree branches, and stalled cars are common on those roads.

[brewdad]

Exactly. There's a reason that curve is marked 25mph (or 15mph even). It's not that a modern vehicle can't negotiate the curve safely above that speed, it's that you can't see far enough ahead to safely stop for anything that might be on the road ahead. Pedestrian, cyclist, or 10 ton boulder.