Dennis, 28, began his WorldTour career with the Garmin-Sharp squad of Jonathan Vaughters but left the team midway through the 2014 season after they agreed to allow him to break his contract to move to BMC.
He helped the team to back-to-back team time trial victories at the World Championships, and in 2015 he won the opening time trial of the Tour de France and wore the yellow jersey for a day.
In the past couple of seasons, Dennis has sought to expand on his qualities against the clock and target the general classification in stage races, including the Grand Tours. At this year's Giro d'Italia he wore the pink jersey, won the stage 16 time trial, and finished 16th overall, though nearly an hour down on winner Chris Froome.
It's a path he is set to continue at Bahrain-Merida, where he will act as a secondary option away from the team's figurehead Vincenzo Nibali, much like he has done with Richie Porte at BMC over the past year or so.
"I am extremely excited to be joining Bahrain-Merida for the next two years. The organisation has been upfront and honest about their plans and objectives for me the entire time, which is really positive. As I know, we are working towards the same goals," said Dennis.
"I’m looking forward to working with a team that is going to invest in my future and I am very keen to see what we can achieve together. I would like to thank all at BMC for a great past four years where I felt I made good progress in my career and I can’t wait to continue that progress with Bahrain-Merida."
Dennis is the latest in a string of departures from BMC, who came close to folding before eventually being saved through a merger with CCC Sprandi Polkowice. He is also one of many new arrivals at Bahrain-Merida, who are refreshing their roster after nearly two years of existence.
Damiano Caruso and Dylan Teuns are two fellow BMC riders joining Dennis next year, while the team have also signed sprinter Phil Bauhaus and lead-out man Marcel Sieberg, along with British neo-pro Stevie Williams.
"Making this announcement makes us all very proud," said Bahrain-Merida general manager Brent Copeland. "Rohan adds a great value to the team, not only as one of the world's best time trialists, but we believe his ability to race in the general classification of Grand Tours is where we want to invest in and we are all very excited to be able to work together.
"Rohan is a true professional in all areas and we feel his professional mentality fits our team perfectly. His enthusiasm and exciting way of racing will definitely bring something special to the team. We welcome him and we’re excited to be able to support him through all his success he deserves with us."
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