According to a recently released study conducted by an international team of scientists in Belgium and the Netherlands, traveling at speeds outdoors dramatically changes safe spacial requirements.
Without taking into consideration wind speed or direction, here are examples of the space that would need to be maintained between cyclists and between pedestrians to keep people safe as they bicycle or walk directly behind someone:
OVERTAKING ANOTHER CYCLIST: In order to safely pass another cyclist when there is no wind, one must start to move over at the same distance that is required to keep out of the slipstream of the cyclist ahead. The cyclist trying to pass must ride in a straight line outside of the slipstream. So assuming you are riding at a fast speed and on the right side of the road, you would have to travel in a straight line in the adjoining lane starting when 66 feet behind the cyclist in front in order to catch up AND continue in the adjoining lane in a straight line for 66 feet after passing before moving back into position in the right lane.
Given all the above, there is little chance that a group ride can be conducted safely. Furthermore, wind conditions were not taken into consideration within this study, which would likely change the safe spatial requirements. Please be responsible and ride solo or with members of your household.
Without taking into consideration wind speed or direction, here are examples of the space that would need to be maintained between cyclists and between pedestrians to keep people safe as they bicycle or walk directly behind someone:
- PEDESTRIANS: each pedestrian must walk 13 to 17 feet behind the person directly in front in order to keep themselves out of the slipstream (air containing molecules released by the preceding pedestrian.)
- CYCLISTS: at slow speeds: such as cyclists traveling at 8 mph, each rider must stay at least 33 feet behind the cyclist in front of them, to keep themselves out of the slipstream (air containing molecules released by the preceding cyclist.)
- CYCLISTS: at fast speeds: such as cyclists traveling at 16 mph, each rider must stay at least 66 feet behind the cyclist in front of them, to keep themselves out of the slipstream (air containing molecules released by the preceding cyclist.)
OVERTAKING ANOTHER CYCLIST: In order to safely pass another cyclist when there is no wind, one must start to move over at the same distance that is required to keep out of the slipstream of the cyclist ahead. The cyclist trying to pass must ride in a straight line outside of the slipstream. So assuming you are riding at a fast speed and on the right side of the road, you would have to travel in a straight line in the adjoining lane starting when 66 feet behind the cyclist in front in order to catch up AND continue in the adjoining lane in a straight line for 66 feet after passing before moving back into position in the right lane.
Given all the above, there is little chance that a group ride can be conducted safely. Furthermore, wind conditions were not taken into consideration within this study, which would likely change the safe spatial requirements. Please be responsible and ride solo or with members of your household.