In reply to Palomino1hills:
You could also try Nick Crane's "Atlas Biker" isbn 1-85509-210-7 .
I'm afraid I've not read my copy so can't offer an opinion.Old school 1980s rigid fork, hardtail, rim brake bikes so probably rather comparable to modern gravel bike. The Cranes did some properly adventurous cycling expeditions though and there may be some tough going on their itinerary.
PS I understand that regulations/security on the trail from Imlil to Toubkal now require local guides to be employed.
Edited spelling
Post edited at 20:26