For the Sandblast Rally moto I am giving 14/52 a try on my 450 berg. I mostly use the bike for tighter technical riding and the 13/52 combo was good for about 70 mph. I figured I'd play it safe and go one up in the front as I will be in a lot of deep sand. On a 570 15 might be fine...look forward to hearing what others ran in other rallies for gearing.
My intuition nearly makes up for my lack of good judgement.
Just installed my new trolling motor