Barra is essentially one ring road, the A888, that loops the island in about 14 miles. The road is paved, narrow, and gentle in gradient — perfect for cycling, with bike rental available in Castlebay. There is a small island bus service (the W32) that runs a few times a day, useful for connecting Castlebay to the airport and the ferry pier at Aird Mhòr.
Cars can be brought on the Oban ferry or hired from a small fleet in Castlebay (book well ahead in summer). Hitchhiking is unusually easy; locals expect to give visitors a lift.