Shange shattered the 19-year-old national record in the men’s 20km walk previously held by his coach, Chris Britz.
The 24-year-old athlete, who broke the SA 3 000m mark on the track in Pretoria last week, finished second at the Lugano Trophy in Switzerland on Sunday in 1:21:50.
He improved Britz’s former mark by 31 seconds and chopped more than two minutes off his own previous personal best.
Elsewhere, 41-year-old Van Dyk won the men’s wheelchair race at the New York City Half-Marathon in 48:54, crossing the line 17 seconds ahead of second-placed American Joshua George.
Lusapho April took fourth place in the elite men’s able-bodied race in 1:01:21, just five seconds outside his 21km personal best, in preparation for next month’s Boston Marathon.
Kenyan Leonard Korir won the race in 1:01:06, edging out countryman Stephen Sambu in a sprint finish.