We have suggested parking in Dungloe, but any of the towns along the coast are a good start/finish spot.
Donegal is an area that is growing rapidly in popularity as a holiday and leisure destination, but at first look may seem bereft of much in the way of biking.
So, what about us poor bikers, stuck up there for whole weekends or weeks at a time? TrailBadger's advice is to purchase a few of the Ordnance Survey maps, plan a route, and just get out and explore!
Much of Donegal is soft, peaty ground, meaning that it is not normally possible to engage in much by way of open mountain or single-track, but the scenery on the coast is truly fantastic, and the county is riddled with hundreds of tiny roads and rough tracks, all of which make for a great day out, and particularly an all-day epic. If you are a down-hiller, forget it, but the XC stuff is brilliant.
If exploring, it is not a great idea to head out without a map, as many of the bog roads lead to dead-ends half way up a mountain, but with the map, you can put together a route that links as many of these together as possible, and gives great continuity for a great day out.
Depending on where you want to ride, the maps you will need are Discovery Series 1, 2, 3, 6, 10, 11. That covers the whole county.