Mr Bradley, from Kilrea, Co Londonderry, was killed after the car he was driving crashed into a wall and then plunged into a reservoir near Castlewellan.
SDLP MLA John Dallat said he taught at Ryan’s old school.
The politician said there was shock and disbelief and shock in Kilrea at his untimely death.
“This was the tragic loss of a very good young man who was extremely popular with everyone,” Mr Dallat said.
“He had friends in all communities and across Ireland.”
Mr Bradley was in his 20s and was a member of Magherafelt and District Motor Club.
Club chairman James McKeefry said the club was devastated.
“I was competing with another crew at the event when I received the word,” he said.
“We went immediately out to be with Ryan’s friends and family.
“It is devastating for anybody that knew Ryan and anyone from a rallying background. It is just devastatingly sad and we will try and help everyone through it.”
The rally began just before 10:00 BST on Saturday from the centre of Castlewellan.
About 70 crews headed the short distance to the first test at Lough Island Reavy and were due to go to Katesbridge, before returning to Castlewellan Forest Park for service.
The accident happened as Mr Bradley was taking part in the first stage of the event at about 11.30 am.
Police divers recovered Mr Bradley’s body. His co-driver was taken to hospital, but he was not thought to be seriously injured.
As a mark of respect, Rathfriland Motor Club organisers cancelled the event.
In a statement they said: “The thoughts of Rathfriland Motor Club, and everyone involved with the event are with the family and friends of the deceased at this time.
“As with all incidents of this nature, an investigation is now being carried out by the PSNI and appropriate local authority.
“Rathfriland Motor Club together with the sport’s governing body, the Motor Sports Association (MSA), are co-operating fully with the investigation.”