Roglič switched bikes with around 20km to go on the shores of Lake Como and on his team-mate Antwan Tolhoek's bike, crashed on the Civiglio descent. He lost 40 seconds to his rivals including race leader Richard Carapaz (Movistar) and Vincenzo Nibali (Bahrain-Merida).
"Actually, I'm bleeding the most here from the face but it's not so hard, so luckily, I don't pedal so much with the face," Roglič joked.
Roglič was the race favourite in the first two weeks but appeared isolated at times in recent stages. He stopped to change bikes at 20km remaining on stage 15, the team saying that their car was behind, so he was forced to take the bike off of Tolhoek.
"I actually didn't have my bike so everything is a little different and I was a little too fast in the corner, but I was happy we did that, so not a big deal," he added.
"Yeah, not the best, but also not the worst, so at the end, I'm happy with it.
"Unlucky? Yeah, it's true, but like I said, it's still some days to go.
"I'm OK, I'm happy that I finished the stage and now I'm looking forward to tomorrow's rest day!"
Roglič chased back on along the shores of Lake Como, rejoined, but Simon Yates (Mitchelton-Scott) and then Nibali attacked. Carapaz joined Nibali, and they joined earlier attacker Hugh Carthy (EF Education First), holding 17 seconds at the top of the climb.
"They went good but I actually think that they weren't so much in front at the top of the climb, so yeah, what can I say? It's still a long race to go," said Roglič.
"Yeah, it's true [I lost time], but like I said, it's still some days to go."
Team sports director Addy Engels said that he stopped so he could pee and that is why he was not there with the team car to give Roglič his spare bike. Tolhoek had to take a spare bike from Movistar to continue.
"We supplied him with a few bottles and we needed quick break to take a pee," said Engels. "The moment we got into the car, I don’t know what happened, but we heard on the radio that he needed a new bike. In terms of timing and bad luck, it was the worst that could happen.
"I don't know [what was wrong with his bike], it was not possible to pedal with it any more because the derailleur was off the bike, so it was necessary he had to change his bike," team-mate Tolhoek said.
"I first had to get on the bike of Movistar and then on my own bike."
The Giro d'Italia stops for its second of two rest days tomorrow. It continues with six days, four in the mountains before the time trial finish in Verona.
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