- Riding side-by-side within a single marked travel lane increases visibility, deters unsafe same-lane passing by motorists, and makes the group more compact. For more information, see Why Cyclists Ride Two Abreast.
- Two abreast (double file) is the preferred, default formation for group cycling.
- Avoiding more than two abreast facilitates rotation and passing by other bicyclists in the remaining space within the same lane, provides more room for maneuvering and provides shy distance to the centerline, which helps following motorists see what’s ahead and avoids unintentional encroachment by bicyclists into the adjacent lane.
- Riding between lines of bicyclists increases the chance of wheel overlap, which causes crashes when a front wheel touches a back wheel. Staying in a predictable line reduces this risk.
- Riding three or more abreast is useful when stopping and restarting at intersections to maximize throughput, if the lane is sufficiently wide. Cyclists should return to no more than two abreast after leaving the intersection.
- Riding single file:
- Increases the length of the group
- Encourages same-lane passing
- Can increase the risk of collision if motorists try to pass where the usable pavement width does not allow safe passing of the group with traffic present in the adjacent lane
- Can be useful to facilitate passing as a courtesy under safe conditions (wide pavement, no junctions)
- Cyclists should choose carefully when to go single file; see “Handling Road Characteristics.”
- Changing group formation on the road requires time, distance, planning, and cooperation.
- Don’t expect to make frequent changes in formation.
- Always look back and yield before moving laterally.
- Announce and signal maneuvers.
- Make movements slowly and predictably.