Paige Robinson, 24, and 47-year-old ex-Army officer David Ferry are each charged with casing death by dangerous driving of cyclist Graham Pattison.
He was struck and died of his injuries on the A689 between Sedgefield and Wolviston in July 2020 following an incident between Robinson, who was driving a Ford Fiesta, and Ferry in an Audi TT.
Each blames the other for acting aggressively towards them, and told the jury neither saw Mr Pattison, a 49-year-old father of two.
During the trial at Teesside Crown Court, Robinson told the jury that Ferry swerved very close towards her causing her to veer left and right in the lane as she tried to correct herself.
She said she was “petrified” she was going to collide with Ferry and was concentrating on where he was, so did not see Mr Pattison on his bike until he hit her windscreen.
Robinson, of Geranium Close, Billingham, denied her boyfriend who she was with was annoyed with the Audi but said they had been singing to N-Dubz on the radio.
Defending himself, Ferry, of Granville Terrace, Redcar, claims he was being “aggressively harassed” by the Fiesta including tailgating, rude gestures and flashing its lights which he said he tried to ignore.
He said he also did not see Mr Pattison or the collision saying he would have stopped to offer first aid.
On Wednesday, their defence barristers made their closing speeches to the jury, who are due to retire soon to consider their verdicts.