Born in Myjava, Valach made his official debut as an amateur cyclist at the 1996 Summer Olympics in Atlanta, where he finished sixty-eighth in the men's road race by less than a second behind the peloton leader Abraham Olano of Spain, recording his personal best time in 4:56:48. During his amateur career, Valach has claimed three Slovak titles in elite national championships (1997 and 1998) until having shown his great talent and passion for sport, he turned professional in 1999 with .