ok i bought a schwinn 210 fs just to get into shape abd see if i wanna get serious about mountain biking,anyways it has RST 191 omni's on the front,there is a hex nut underneath on each side is this to adjust them?they seem a bit soft but i also weight 250lbs so maybe i'm just to heavy,i had some roch shock judy's lined up for $50 but buddy never came through i guess...