Mahlknecht celebrated his first major successes at the Junior European Championships from 1983 to 1985. He started in the single-seater and together with Erwin Antholzer also in the double-seater. In 1983 he won bronze in the doubles in Montreux , but remained just behind the medal ranks in the single-seater as fourth. In 1984 in Hol and 1985 in Oberperfuss , he won the gold medal both times in the single-seater as well as in the double-seater and was thus four times Junior European Champion.
In the World Cup , Mahlknecht achieved third place in the overall single-seater World Cup with a victory in the last race in Bruck an der Großglocknerstrasse in the first season in 1992/1993 . The next winter he won the season opener in Völs, achieved three second places in the other four races and was therefore tied with Franz Obrist overall World Cup winner in the single-seater. Mahlknecht ended his career with this success.
Harald Steyrer, Herbert Wurzer, Egon Theiner: 50 years FIL 1957 - 2007. The history of the International Luge Federation in three volumes . tapeII . Egoth Verlag, Vienna 2007, ISBN 978-3-902480-46-0 , p.285-397 .