The R25/4 course has been amended to avoid the 20mph speed limit in Llandovery and has been given the 'R25/4 (emerg)' course title. Here is a Garmin course of the approximate route:
https://connect.garmin.com/modern/course/266084325
R25/4(emerg) Course Description:
Start at southernmost point of the northern entrance splay of the layby S side of A40 immediately S of Llanwrda (OS 146 GR711312). Proceed SW on A40 to Llangadog r/a (2.5 miles). Take 2nd exit (straight on) (CIRCUIT START) to continue SW on A40 through Manordeilo , Rhosmaen to Llandeilo r/a (7.5 miles).Encircle roundabout taking 3rd exit to continue NE on A40 via Rhosmaen, Manordeilo, to Llangadog r/a (12.5 miles). Encircle r/a taking 4th exit (to complete 1st circuit). REPEAT CIRCUIT (via Manordeilo, Rhosmaen Llandeilo r/a, encircle r/a taking 3rd exit to continue NW on A40 to Llangadog r/a (to complete 2nd circuit (22.5 miles)). Take 2nd exit on A40 to continue NE past ( Abermarlais caravan park) passing Brownhill Farm to pass opposite Start point to FINISH at Northern end of field entrance gateway approx. 400 yards before A482 junction (Lampeter). (GR 710312) 25.08 miles.