Vehicle volumes are regularly collected by transportation agencies, but the lack of data on bicycling suppresses progressive planning for this mode. Smartphone apps bicyclists use to record trips such as Strava are forming a new data collection resource to reverse this problem, but only a small portion of bicyclists contribute to this data source. This study matched a traditional method of counting bicyclists using pneumatic tubes at 5 locations on Austin's trail system to the times and locations of Strava data to identify how these data could be used together to approximate bicycle volumes in other places. Almost 5 percent of bicyclists counted on the trails also recorded Strava trips during the same period, more than any previous GPS-based study of bicyclist volumes. Further research regarding bicyclist smartphone apps are needed to understand how differences in app users' trip purpose and user population may affect planning. UTSOA Community and Regional Planning assistant professor Junfeng Jiao, Ph.D. and doctoral student Greg Griffin, AICP have submitted this research for peer-reviewed publication.