▁making ▁contact ▁with ▁the ▁tr uck s ▁of ▁the ▁sk ate board . ▁Gr inds ▁can ▁be ▁performed ▁on ▁any ▁object ▁narrow ▁enough ▁to ▁fit ▁between ▁whe els ▁and ▁are ▁performed ▁on ▁cur bs , ▁rails , ▁the ▁cop ing ▁of ▁a ▁sk ate ▁r amp , ▁fun box es , ▁led ges , ▁and ▁a ▁variety ▁of ▁other ▁surfaces . ▁ ▁History ▁ ▁The ▁move ▁likely ▁origin ated ▁in ▁back yard ▁po ols ▁in ▁the ▁early ▁' 7 0 s ▁, ▁as ▁the ▁early ▁sk aters ▁gained ▁in ▁skill ▁and ▁confidence ▁with ▁their ▁high ▁speed ▁car ves ▁around ▁the ▁top ▁of ▁the ▁pool ▁walls ▁and ▁one ▁day ▁went ▁that ▁little ▁bit ▁ ▁too ▁high ▁. ▁The ▁tr uck s ▁of ▁the ▁time , ▁often ▁being ▁merely ▁' bor row ed ' ▁roll ers k ate ▁tr uck s ▁, ▁didn ' t ▁allow ▁much ▁contact ▁due ▁to ▁their ▁narrow ness , ▁but ▁as ▁sk ate board ing ▁gained ▁its ▁own ▁tr uck ▁manufact ur ers ▁who ▁w iden ed ▁the ▁h anger ▁design , ▁the ▁possibilities ▁for ▁expl oration ▁became ▁apparent , ▁and ▁all ▁sorts ▁of ▁moves ▁started ▁po pping ▁up ▁. ▁There ▁was ▁a ▁big ▁le ap ▁in ▁street ▁sk ating ▁starting ▁in ▁the ▁' 9 0 s ▁. ▁It ▁has ▁evol ved ▁ever ▁since . ▁Today , ▁gr inds ▁are ▁commonly ▁performed ▁on ▁hand rails , ▁lips ▁of ▁ben ches , ▁tables , ▁hub bas ▁( ledge ▁on ▁a ▁slope ), ▁on ▁a ▁hard ▁normal ▁led ge , ▁a ▁flat