Abstract 
Understanding how Citibike trip durations change throughout the day can give insight into the patterns of bike use, potentially suggesting how morning and evening commutes impact rides or when people choose to take longer rides. Looking at Citibike rides in June 2017, a Mann-Whitney U Test was performed on trip durations categorized by hour of the day, specifically comparing trips that start in the commuting hours of 8 AM and 5 PM to every other hour of the day. The test was used to find whether these commuting hours distributions of trip durations are significantly greater than the other hours of the day. The results of the test revealed that 8 AM had a significantly greater distribution than only the hours between 11 PM and 9 AM, while 5 PM was found to have a significantly greater distribution than every other hour. 
Introduction
Citibike is a bike sharing program in New York City that allows users to unlock a bike from one of hundreds of Citibike stations across the city, ride the bike, and return the bike to any station. Citibike has made a portion of its data publicly available, which describe every individual bike ride back to 2013. \cite{nyc}
The data associated with each trip include categories such as trip duration, start and stop time, start and stop location, age and gender, and several other descriptors. Focusing on the trip start time and trip duration of each ride, it may be possible to understand traffic congestion as it relates to bike rides during peak commuting hours in New York City. Finding which hours of the day average trip durations are longest can help generate insight into either how bike riding behavior changes throughout the day or how bike rides are impacted by traffic. \cite{data}
Data
The data used in the analysis included only the 1,731,594 Citibike trips that occurred in June 2017. After removing outliers, each trip duration was converted from seconds to minutes, and then given a column to denote the hour in which the trip began based on the trip start time.