Updated January 12, 2025 The Gigante de Piedra 2025 is a formidable mountain bike ultramarathon held annually in Castellón, Spain. Renowned as one of the toughest MTB races in Spain and possibly Europe, it challenges participants with a grueling 200-kilometre course featuring approximately 6,500 meters of elevation gain.  Strambecco rates the event as one of Spain's…