John enjoyed a good career between the sticks - making over 400 appearances - earning four promotions with the likes of Cambridge, Preston and Lincoln City.
The Reds' new Goalkeeper Coach expressed his excitement at joining Lee Johnson's coaching staff, "I'm really looking forward to working with Lee Johnson and the rest of the staff and players," said John.
"It's a genuinely exciting time for everyone connected with the Club. We have got some really talented players, including our goalkeepers, and I can't wait to get cracking for the new campaign."
