Lane and parking reductions have become common practices in major American cities, notably for the installation of bike lanes. Proponents argue that these measures increase safety and reduce greenhouse gas (GHG) emissions. However, evidence supporting this argument remains elusive, especially considering the sprawling nature of American cities. I explore this question by leveraging Montreal’s natural experiment, which aims for 15% of all trips to be made by bicycle by 2030, supported by a half-billion-dollar budget. Specifically, the city is rolling out the Express Biking Network (EBN) to connect each neighborhood through protected bike lanes. Utilizing the first deployed axes and the city-owned bike sharing data, I estimate that the added bike lanes have increased bike ridership by 30% within 300 meters of the new lanes, decaying to 20% in the 500-meter buffer; the 10% increase in speed and distance is believed to be a driving factor. Contrary to popular belief, this increase does not come at the expense of nearby bike lanes, which instead experience a positive spillover effect, underlying that these are additional bike riders. However, if the objective is to offer a sustainable transit mode, it is crucial to determine whether these additional bikers are shifting from the public transit network. To this end, I find weak to no evidence that the additional bikers stem from the subway network. Our triple difference-in-difference analysis —using seasonal variations to neutralize work-from-home effects suggests an insignificant 1% decrease in subway ridership. Finally, while I cannot establish causality, I observe a 15% reduction in car usage, which could explain the increase in bikers. In summary, my research underlines that, despite having a harsh climate and challenging terrain, as is the case in Montreal, protected bike lanes can significantly boost bicycle usage with a negligible impact on the public transit network.