You enter a bend near Vijlen and judge the radius on entry. Halfway through, the bend turns out to tighten more sharply than expected. What is going on here according to the book?
A bend radius is fixed on entry and does not change after that, this must be a different bend
Some bends curve increasingly sharply inward; your first assessment can become outdated
Explanation
False — trap: a one-time assessment treated as valid for the whole bend. The book explicitly warns that some bends curve increasingly sharply inward (Book p.67).