The collision involved two motorbikes, a Honda and a Kawasaki, not a van as previously reported by Lincs Police, at 3pm on Sunday 1st June on the A631 Gainsborough Road at Hemswell.
The rider of the Honda remains in Hull Royal Infirmary in a critical condition and his injuries are described as life threatening.
He is aged in his 50s and is from South Yorkshire.
The 48-year-old rider of the Kawasaki received minor injuries.
Police are urging anyone who witnessed the collision, who has not yet given their details to call 101 or the collision hotline on 01522 558855.