In 2018 Mountain Bike Australia released the Australian MTB Trail Guidelines which included a revision of the Trail Difficulty Rating System (TDRS).
The TDRS, which is used to grade mountain bike trails according to their relative technical difficulty, underwent a further revision in October 2020.
The Australian TDRS uses the IMBA system of classifying trails with the following additions and interpretations:
In terms of changes between the 2018 and 2020 versions of the TDRS, the following revisions were made:
A copy of the revised TDRS table which highlights the changes between the 2018 and 2020 versions, was emailed to all those who purchased a copy of the Australian MTB Trail Guidelines. A copy of the 2020 version and summary of changes is available on the AusCycling website.