To understand a bicyclist’s route choice is difficult, given the many factors that influence the attractiveness of different routes. The advent of low-cost GPS devices has made route choice analysis more precise. Bikeshare, with instrumented bikes, allows for better assessment of revealed route preference of a large subpopulation of cyclists. This study used GPS data obtained from 9,101 trips made by 1,866 users of Grid Bikeshare, Phoenix, Arizona. This unique bikeshare system relied on Social Bicycles’ onboard telematics, which allowed nonstation origins and destinations, and operated on a grid street network. The system enabled unique route choice analysis. The trips studied included only direct utilitarian trips. Circuitous trips that could have included multiple destinations or could have been recreational trips were removed. The analysis focused on facility use assessment and route choice behavior. The results were compared between two categories of bikeshare users: registered users and casual users. Registered users made shorter trips on roads with low volume and preferred bike-specific infrastructure. A path size logit model was used to model route choice. Riders were sensitive to travel distance, with little deviation from the shortest path to use more bike-friendly infrastructure. Travel on the bike-specific facilities was equivalent to a decrease in distance by 44.9% (compared with 53.3% for casual users). Left turns imposed higher disutility than right turns did for casual users. The proportion of one-way segments, annual average daily traffic values, and length of trip had a negative influence on route choice, and a number of signalized intersections had a positive influence on route selection. The results were also compared with those of earlier studies.