Melbourne's first ever public bike hire scheme is underway with the roll-out of the first 100 bicycles - although the government will not say how many people are expected to use the scheme.

The distinctive electric-blue bicycles will be available at 10 docking stations across the CBD. Subscribers will be able to join the scheme for $50 a year, $8 a week or $2.50 a day. Users will then be able to take the bicycles for 30 minutes without charge.

MAP: Melbourne Bike Share stations

But Roads Minister Tim Pallas, who launched the scheme at Melbourne University this morning, would not say how many people the government expects to use the scheme.