NOVELTY - Increasing the enzymatic accessibility of a thermally treated lignocellulosic biomass feedstock which has been thermally treated at a severity factor, where the thermally treated lignocellulosic biomass feedstock comprises xylans, glucans and lignin and is in physical forms of fibers, fines and fiber shives, where the process comprises a fiber shives reduction step.    USE - The method is used for increasing the enzymatic accessibility of a thermally treated lignocellulosic biomass feedstock which has been thermally treated at a severity factor (claimed).    ADVANTAGE - The thermally treated lignocellulosic biomass after fiber shives reduction is characterized by having an increased glucans accessibility and by forming a slurry having a low viscosity.    DETAILED DESCRIPTION - Increasing the enzymatic accessibility of a thermally treated lignocellulosic biomass feedstock which has been thermally treated at a severity factor, where the thermally treated lignocellulosic biomass feedstock comprises xylans, glucans and lignin and is in physical forms of fibers, fines and fiber shives, where (i) the fibers each have a width of 75 mu m or less, and a fiber length greater than or equal to 200 mu m, (ii) the fines each have a width of 75 mu m or less, and a fine length less than 200 mu m, (iii) the fiber shives each have a shive width greater than 75 mu m with a first portion of the fiber shives each having a shive length less than 737 mu m and a second portion of the fiber shives each having a shive length greater than or equal to 737 mu m, where the process comprises a fiber shives reduction step, where the percent area of fiber shives having a shive length greater than or equal to 737 mu m relative to the total area of fiber shives, fibers and fines of the thermally treated lignocellulosic biomass after fiber shives reduction is less than the percent area of fiber shives having a shive length greater than or equal to 737 mu m relative to the total area of fiber shives, fibers and fines of the thermally treated lignocellulosic biomass before fiber shives reduction, where the percent area is measured by automated optical analysis.