We don't have synonyms for bikie yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are bike, bixie and birkie.
"A luxury waterfront flat believed to be owned by a Hells Angels bikie in Sydney was searched by police this afternoon. — Dylan Welch, Sydney Morning Herald, February 19, 2008"
"A luxury waterfront flat believed to be owned by a Hells Angels bikie in Sydney was searched by police this afternoon. — Dylan Welch, Sydney Morning Herald, February 19, 2008"