If you can't get it to route you to the first waypoint/starting point by selecting the actual start point itself of your hike or bike route as the destination [or one on a nearby road location you can drive to] it's because it doesn't have a routable map loaded to take you there. If it has a routable map loaded and enabled the 64 should be able to navigate you on-road by vehicle to that point.
Your 64st comes preloaded with Topo US 100K which is not a 'road routable' map. From the relevant Garmin page:
• Includes updated road content, by NAVTEQ (non-routable),
• Contains detailed hydrographic features, including coastlines, lake/river shorelines, wetlands and perennial and seasonal streams.
• Includes searchable points of interests, such as parks, campgrounds, scenic lookouts and picnic sites.
• Provides elevation profile on compatible devices so you can estimate terrain difficulty.
• Contains roads, trails and highways in metropolitan and rural areas so getting to your destination is easy by creating point-to-point routes on compatible devices.
• Displays national, state and local parks, forests and wilderness areas.
So you'll need to load a routable map such as a City Navigator or some other a routable map, or create a series of waypoints from your current location to the start point of your route for use with your 100K Topo.
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