Torontonians roll down Yonge Street toward Nathan Phillips Square on Bike to Work Day. (Dwight Friesen/CBC)

A debate is underway at Toronto City Council over whether to lose one lane for vehicular traffic on Jarvis Street in order to create two bike lanes.

The idea is part of an overall $6-million project to revamp Jarvis. The bike lanes would cost up to $100,000.

Mayor David Miller supports the bike lane idea and the redesign.

So does Cliff Seymour, an ardent cyclist in the city.

"Going down Jarvis very bad," said Seymour. "You've got to be careful."

The debate comes at the official start of Toronto's bike month.

Nathan Phillips Square, in front of city hall, was swamped with cyclists on Monday morning for the 20th annual "Group Commute" breakfast.

The plan is to narrow Jarvis from five to four lanes. The north-south street is one of the rare ones in Toronto that has a middle lane that changes direction during the morning and evening rush hours.

Eliminating the middle lane would create space for two bike lanes.

Coun. Karen Stinz pointed out there are 27,000 cars using the road during rush hour every day. Compare that, she argues, with 20 to 30 bikes.

Another councillor, Doug Holyday, thinks the bike lanes are a waste of money, given there are others in the city, he says, that are barely being used.

"That's very much like bike carriers on [TTC] buses. I've yet to see a bike on one of those carriers. Now, how much more money are we going to spend on the speculation that people are going to start riding their bikes for transportation [and not for] recreation here in the city of Toronto?"

But Miller says cycling must be a real choice for people in the city.

"Transportation is not about moving cars, it never has been and never should be. Transportation is about moving people," Miller said during the debate.

The mayor thinks redesigning Jarvis Street would cause minimal inconvenience and rejuvenate the neighbourhood while allowing cyclists and drivers to share the road.