The 25-year-old Buchmann will be tasked with securing a top-ten placing while Sagan and Majka will be on the hunt for a stage win to meet team KPI's.
"I think I am ready. It is an honour the lead such a big team like BORA-hansgrohe at a Grand Tour, but I’ll do everything to meet the teams’ expectations, Buchmann. "I prepared very conscientiously and the whole season went well so far.
"This will be my biggest challenge so far as a cyclist, but I feel I am at my best. I did everything to arrive here in perfect shape, now we need a little bit of luck to come through the Vuelta without any crashes or other setbacks."
Sagan, who on Sunday finished 10th overall at the EuroEyes Cyclassics Hamburg, is still suffering from the after-effects of his crash at the Tour de France as he prepares for a testing defence at the UCI Road World Championships in Austria.
“I decided to race the Vuelta this year, as it fits perfectly into my preparations for the World Championships in Innsbruck," Sagan said. "We’ll have to see how my crash at the Tour still affects me, but I feel I am on a good way back to my best.
"There are a lot of interesting stages at the Vuelta. We have a really strong team here in Spain, and a lot of cards to play when it comes to stage wins and of course, I’ll also try to take one as well.”
SBS will broadcast all stages of the 2018 Vuelta a España.