In a bid to boost cycling numbers in Brisbane the city's public transport boss Adrian Schrinner has challenged Main Roads Minister Mark Bailey to make helmets optional.

On Thursday morning Cr Schrinner posted on Twitter that he was delighted with the use of Brisbane's CityCycle bike share scheme, with more than 1.9 million trips since its introduction in 2010.

Public transport boss Adrian Schrinner says Brisbane' could benefit from voluntary helmet laws. Credit:Michelle Smith

A reply from Melbourne PR agency MediaWise said if helmet laws were relaxed trips would soar.

"It's not rocket science, just how the rest of the world succeeds in bikeshares," the tweet said.