John Scotson was fatally injured after the scrambler he and pal James Glover were riding careered into a metal barrier at twilight.
It is still not clear which of the two men were at the controls of the vehicle and who was riding pillion.
The pair had taken the blue 250cc off-road bike for a test ride at around 8.30pm on Monday and, after driving around the Lowton area, ended up making their way into Pennington Park. Police say they were riding along a bridleway when they tried to negotiate a left-hand bend and collided with a metal gate across the path.
Mr Glover, who is 23 and from the St Helens area, broke both a leg and a hand and also sustained a minor facial injury.
He found his friend unconscious with severe head injuries and contacted a friend who in turn called for an ambulance.
A search of the area was carried out and shortly after 11pm the two men were found.
Mr Scotson, 27, from Newton Road, Lowton, was pronounced dead at the scene by paramedics and a post-mortem examination was due to take place at Wigan Infirmary last night (tues).
Mr Glover remains at Wigan Infirmary and is to be quizzed further by traffic officers about the accident.
The deceased's partner, Kate Collier, was today said to be overcome with grief and was being comforted by relatives. Mr Scotson also leaves a two-year-old daughter, Leah.
Officers would not comment today on whether the two riders had been wearing crash helmets.
Sgt John Brennan, of the Wigan, Leigh and Bolton Road Policing Unit, said: "This was a tragic incident in which a young man lost his life.
"At this stage, it is unclear exactly what happened and I would appeal to anyone who might have seen these two men riding this motorbike at about the time of the collision to come forward and help us."
Anyone with information about the collision is asked to call the road policing unit on 0161 856 7201.