The Trofeo Calvia, which is the opening race of Challenge Mallorca, takes place in the Serra de Tramuntana mountain range.
It spans 155 kilometers and features a 3,100-meter climb.
There are no steep climbs along the route, but rather a series of snaking and rolling ascents.
McNulty spent the last 60 kilometers of this time-trial mode ahead of the pack and crossed the finish line alone, elated to capture his first win for the UAE Team Emirates.
His victory stands out because it was not measured or paced according to any scientific method.
McNulty won this race on a gut feeling as he forgot to put on his heart rate monitor before the start and his power meter broke down 20 kilometers into the race.
Without any gadget to guide him, the 23-year-old survived the winding Mallorca hills, and with just over 60 kilometers to the finish line, he broke from the pack and managed to build up a one-minute lead.
McNulty held onto this lead as the chasing pack behind him tired and achieved his first win as a World Tour competitor.
After winning, he uploaded his ride to Strava and, along with a laughing emoji, captioned it: “Great day to forget the heart rate strap and for the power meter not to work.”
Analysis showed that McNulty had covered the race at an average speed of 37.2 kilometers per hour.
McNulty is now aiming to continue his triumph as he plans to race in the Tour De France and the Vuelta a Espana this year, two of the grand tours for cycling.