Four-time British champion Keith Farmer has announced his retirement from racing following "two relatively big crashes" this year.
Farmer had originally planned to retire at the end of the year.
He had been competing in the National Superstock Championship but was offered a ride in the Superbike class by iForce Loyd & Jones BMW for the Silverstone meeting.
He said: "I have had a tough year but that's just racing. I have realised that it is time to walk away.
"I've had 10 good years of racing in the BSB paddock riding for some of the best teams."
Farmer won the National Superstock 600 title in 2011 and National Superstock 1000 successes came in 2012 and 2018 - he also won the British Supersport title in 2017.
He added that he made the decision to retire earlier than planned following the crashes, with "one taking out Takumi Takahashi which I am sorry for and the other smashing myself to bits.
"I count myself extremely lucky to have been given these opportunities and with these I have won four British titles.
"I will still be watching and keeping an eye on everything, and maybe next year I could start something new."