The man from Leeds, who is aged in his twenties, was airlifted to Leeds General Infirmary and is in a stable condition after the incident on the B6451 at Norwood near Otley.
Another male cyclist, also from Leeds and aged in his twenties, suffered minor injuries in the collision, which happened at around 1.40pm on Monday, May 26, around one mile from the Sun Inn on the Otley side.
The livestock carrier was driven by a man in his 40s from the Silsden area.
The road was closed to allow collision investigators to examine the scene and reopened at around 7pm.
Police are asking for anyone who stopped at the scene of the incident to contact them if they have not already done so.
They are also to hear from anyone who was travelling along the stretch of the B6451 from Otley to the Sun Inn, who saw either the green livestock carrier or the cyclists before the collision and anyone who witnessed the incident.
Anyone with information can call North Yorkshire Police on 101, asking for traffic constable Steve Wright at Harrogate Roads Policing Group.