In recent years considerable effort has been made here in Australia to adopt building techniques that make recreational trails for walking, mountain biking and horse riding more durable and have less impact on their surrounds than most of the trails built in earlier times. The guidelines for such construction are published by the International Mountain Bicycling Association (IMBA). Trail builders in Australia have been encouraged to adopt the guidelines through the efforts of Mountain Bike Australia (MTBA) and its subsidiary IMBA–Australia (IMBA-Au). How "sustainable" are these mountain bike trails? Several previous studies in Australia, New Zealand, England and the United States have produced results that rely on a single measurement of a trail transect profile and an assumption of where the trail surface lay when the trail was built. This paper reports on three studies over twelve-month periods of three singletracks built to the IMBA guidelines: two are in South Australia and one is in Brisbane. For each of the trails two parameters were recorded once every three months at twenty randomly-placed transect points. The parameters are (1) the transect profile and (2) the used tread width. The great majority of users on all three trails are mountain bikers with the rest being walkers. Additionally, the number of users for each trail was gathered and the rainfall at the nearest Bureau of Meteorology site was recorded. From these data the amount of wear is estimated under the recorded conditions of use and rainfall. The trail in the Brisbane study was subject to use of 31 passes per day and 1,135mm of rain over the study year and the SA trails experienced just under 700mm of rain each and 14 and 45 passes per day. Of the 60 transects in all three studies, 34 showed no change in transect profile, 18 minimal, 4 noticeable and 4 considerable or substantial. All of these last four deviated to some extent from the guidelines but at none was there evidence of gouging, deep wheel ruts or channels caused by erosion or use. Some of the used tread widths at the transects narrowed and some widened but none of the sixty exhibited tread creep to outside the edges of the trails as built.