Room For Debate uses controversy over NYC's bike lanes to bat the question around. Caroline Samponaro provides basic numbers:

Since the city added 250 miles of bike lanes in the last four years, New Yorkers have voted with their pedals. During that same four-year period, daily cycling counts have more than doubled. It's this growth -- cycling is up 109 percent since 2006 -- that lets us know how effectively bike lanes make for more bicyclists.

Sam Staley is the most negative:

Getting bike acceptance levels up to those of models like Amsterdam and Copenhagen takes more than striping lanes. It takes a focused anti-car policy that dramatically increases the costs of using automobiles.

Felix Salmon urges patience.