R1 vs R2 programs in mathematics
First of all, I don't give individual advice for prospective math PhD students without saying that the job market for permanent positions (including teaching positions) is terrible and likely to stay that way.  There are significantly fewer jobs than highly qualified candidates.
With that out of the way... You can get pretty much as good an education at a program ranked around 60 as at a program ranked around 20.  It's true that, at the lower ranked program, you will likely have to study some more advanced topics independently with your advisor that you might have been able to take a 2nd or 3rd year graduate course for at a higher ranked program.  But, given the job market, the qualifications of the professors are going to be pretty much the same.  You'll be able to get pretty much just as good an advisor who, if you're capable, will help you work on just as good a project, and the advisor will have pretty much just as good a network to help you promote your work and find a postdoc.
Another difference is the expectations of the culture.  At a program around 60, a student who gets a research postdoc is exceptional.  The professors will not generally push you to do that level of coursework and research until you demonstrate that kind of capability, and your peers will not be expected to do that level of research.  Some people are more likely to make an effort beyond what their peers do; others are not.  I don't know you.
However, you should also realize that, if you are capable of earning a PhD with research that will get you a research postdoc, then every program ranked around 20 will be happy to admit you.  Of course it's somewhat hard to judge the potential of an undergraduate student, but if the higher ranked programs all turn you down and you do get a postdoc after your PhD, then those programs have all made a mistake.  Sometimes that mistake is systemic and out of their control; perhaps all your letters of recommendation underestimated your potential.  This means, though, that failing to get admission to a top 25 program is an indication that admissions committees don't think you're likely to succeed to that extent.