Green’s Dictionary of Slang

(Aus.) a bicycle.

1928		Geraldtown Guardian (WA) 26 May 2/6: He had his bicycle stolen [...] In its place was an ancient ‘mangle’ which he found almost beneath his dignity to mount.
1932		Camperdown Chron. (Vic.) 2 July 8/2: The possession of a ‘grid’ or ‘mangle’, as cycles are popularly known, is the ambition of almost every youth.
1941		Baker Popular Dict. Aus. Sl. 45: Mangle, a bicycle.
1949		Centralian Advocate (Alice Springs, NT) 15 July 5/3: Gaily he hopped on the old mangle and tootled across to the East Side.
1953		A. Buckeridge Jennings’ Diary 61: I’ve had enough of pushing this old mangle.