This is a serious question: "how Do You determine a fun but safe appropriate entry speed for the curves on those twisty two lane back roads?" You know the ones: there is a curve sign, a "suggested" speed, and the almost certain knowledge that there is no LEO waiting around the bend.
Sure, it depends upon conditions. So here are the hypothetical conditions for your response: sunny 70 degree day; pavement dry; pavement good with no potholes and no loose gravel on the road in first three miles - though the shoulder is gravel; slight cambre in both directions from the center line; traffic in both directions very light; almost all curves are "blind" because of rock formations or trees.
Do you check your speedometer? If so, by what percentage do you increase your entry speed over the suggested one? Do you use the suggested speed as an indication of what gear you should use? Do you cover your front brake in curves? Do you believe you could stop within your sight distance? Where do you look approaching and making the turn? (Feel free to add advice or tactics which have served you well.)
Hey, there are two months or more of winter ahead of me. Time to think about riding. Hope this OP rouses some discussion and gets us all thinking about how to ride those twisties we all love in a fashion which brings us home smiling and safe.