CREATE TABLE table_204_535 (id DECIMAL, "pos" TEXT, "rider" TEXT, "manufacturer" TEXT, "laps" DECIMAL, "time/retired" TEXT, "grid" DECIMAL, "points" DECIMAL)

which is the only rider with number 6 grid on the chart
SELECT "rider" FROM table_204_535 WHERE "grid" = 6
SELECT "rider" FROM "table_204_535" WHERE "grid" = 6