The pair were travelling along Lowfield Lane from Kirkby Fleetham in the direction of Great Langton on Sunday lunchtime.
As they approached South Lowfield Farm they were in a collision with a car, which left the scene.
The car involved in the accident around 1.25pm is described as a dark hatchback.
Police are asking anyone who notices recent damage to a car matching that description - possibly to the driver’s side - or has overheard someone talking about the accident to contact them.
They also want to hear from anyone who saw or has dashcam footage of the car in the moments leading up to the crash.
Call PC Lee Stephenson on 101 or email [email protected]