MELBOURNE'S bicycle share scheme needs an injection of $2 million if a cheap-helmet initiative set up by the previous state government is to continue.

The $5 million Melbourne Bike Share scheme was launched in June but was hampered by Victoria's compulsory helmet laws.

In the first months, few riders used the 500 blue bikes placed at stands across the city.

To encourage more riders, the former government in October put subsidised $5 helmets on sale at 7-11 stores and at vending machines in a three-month trial.

Each helmet sold ultimately costs taxpayers $13. So far 5700 helmets have been sold.