Nick Bowdler was best BBAR last year; riding at an average speed of 27.206 mph over three seperate events; a 50, 100 and a 12 hour. he managed 287 miles in the 12 hour. he’s a supremely fit and strong cyclist.
i generalise, but time triallists tend to rely on leg strength and big gears. Nick seems to take this a stage further.
He uses a 76 tooth chainring. Cadence is around 60 rpm, with a 170 inch gear.