North Donegal Coast
From Letterkenny you ride east to the famous Glenveagh National Park before climbing the shoulder of Muckish for great views of the area.
You take in the beautiful Fanad Peninsula before turning south to reach the Gaeltacht in Gweedore – one of the most popular spots in Donegal.
From Gweedore this route visits mighty Mount Errigal (which you can skip to save 18km on the day) before following the coast south as far as Burtonport, near Arranmore Island.
There are regular ferries out to the island. You then return to Letterkenny passing along the spectacular south side of the Glenveagh National Park.