In order to provide reference for urban road planning and design, a traffic survey was conducted under the interruption of roadside bicycles. The influences of the number of roadside bicycles on average travel speed and cars' saturated headway of adjacent lane were analyzed, and the models between them were established respectively by regression method. Based on established models, suggested adjustment factors were given to calculate possible capacity of urban arterial road segment, and case study was conducted. Thresholds of the number of roadside bicycles were presented to evaluate LOS (level of service) and set separate facilities on urban arterial road segment. Results show that average travel speed decrease and cars' saturated headway increases with the increasing of the number of roadside bicycles, and the quadratic function relations between them is observed. The greater the number of roadside bicycle, the higher road design speed, the smaller the adjustment factor, indicating that the influence of roadside bicycle on road capacity is greater. The higher the design speed, and the lower the threshold of the number of roadside bicycles when LOS is the same, showing that the effects of roadside bicycle on traffic operation is greater for urban road segment with higher design speed.