Reduced speed ahead
 

I'm just wondering, legally speaking, there's a "reduced speed ahead" sign, where that new speed limit actually begins? I always thought it was when there was the next regular speed limit sign. However there is one spot on my normal everyday drive where it says reduced speed ahead, and then no sign. Just wanted to ask before I get a ticket for doing 40 in a 25. Thanks.

You are correct, the "Reduced speed ahead" sign serves as a warning that you are approaching a zone with a lower speed limit. If there truly is no posted speed limit sign with a lower limit, pictures/proof would go a long way to getting you out of any possible tickets.