560-580 were pretty common. When downhill got more technical than fireroads and gravel paths Azonic and Answer stepped up with 660, 680 then 710mm bars. There was a fashion for cutting bars narrower than 550 but IMO that was driven by fashion alone, even vintage bikes seem to work best with the widest feasible bars.
In the modern day I run 780mm Renthals on my modern day trailbike, I am wide in the shoulders but the difference in stability over narrow bars is the main reason. I reckon there are maybe two places I need to button off and wiggle it through trees, and I ride some damn tight and technical trails. 680-710 is the common standard nowadays on off-the-peg all rounder mountain bikes.
In the modern day I run 780mm Renthals on my modern day trailbike, I am wide in the shoulders but the difference in stability over narrow bars is the main reason. I reckon there are maybe two places I need to button off and wiggle it through trees, and I ride some damn tight and technical trails. 680-710 is the common standard nowadays on off-the-peg all rounder mountain bikes.