Factory Yamaha’s Jorge Lorenzo, who was not present at the Malaysian GP following a surgery on his finger, published via Twitter: "I don’t know what to say on a day like today ... Only that you will be missed - rest in peace Marco."
Lorenzo’s team mate, Ben Spies, shared: "Super Sic rest easy..."
Nicky Hayden posted: "Sometimes life just don't make sense... RIP #58 you were a star on & off track we all going to miss you."
Cal Crutchlow’s post: "RIP Marco Simoncelli! A great rider and all round nice guy. My thoughts are with all his family & friends. I will never forget today... #58"
Former full time and two time wild card entry this year, John Hopkins, said: "God Speed #58 Simoncelli... Your fighting spirit will live on forever!"
Two time replacement rider this year, Damian Cudlin, shared via Titter: “Terrible news. Marco’s gone. Sad day for motor racing and all the llives he touched along the way. Won’t forget you, mate.”
Kenny Roberts and his family sent the following sentiment: "The entire Roberts Family is deeply sadden by the news about Marco. We wish to send our condolences to his family, friends, fans and MotoGP. We will never forget him!"
Jeff Belskus, the Indianapolis Motor Speedway Corporation President and Chief Executive Officer, shared: "We are deeply saddened at the passing of Marco Simoncelli. He was one of the most charismatic figures in the World Championship and had a fantastic future ahead of him in MotoGP.”
“Marco was one of the most popular riders at the MotoGP event at Indianapolis, as his talent on the motorcycle and his ability to connect with fans both were very special. We extend our sincere sympathies to his family, team and fans."