The purpose of this research was to investigate the estimation accuracy of annual average daily bicycle (AADB) traffic volumes when both daily and monthly adjustment factors (DFs and MFs, respectively) were used. Daily bicycle volume data for a full year were collected at 12 permanent count stations during 2010 in the city of Vancouver, British Columbia, Canada, and used to calculate adjustment factors for bicycle traffic. The factors were applied to estimate the AADB traffic volumes at other count stations where data were available for most of the year. A comparison between the use of MFs and seasonal factors showed that the results supported the superiority of using MFs. Detailed error analyses showed that the lowest errors were attained when the developed factors were applied to the volume data of 2010, which was the same year of the development data. For estimating the AADB with only 1 day of bicycle volume data, daily bicycle volumes were multiplied by both DFs and MFs. A disaggregate error analysis estimated the amount of error attributable to the use of DFs versus MFs. Almost 15% of the estimation error of the AADB could be attributed to the use of DFs, whereas 11% was attributed to the use of MFs. Nevertheless, the overall error of using the two factors together was about 23%. The paper also provides insights on the days and months for collection of data on bicycle volumes. Those insights could improve the design of data collection programs for bicycle traffic.