Epidemiologist Rides a Bike

By now, some of you may have heard of the Dutch/Belgian study whose authors recommended that fast runners maintain at least 10 m distance and fast cyclists maintain at least 20 m distance from others in their “slipstream”. It received a lot of media attention, enough that runners and cyclists felt a bit demonized.

The researchers used existing wind tunnel measurements to computer simulate how far droplets traveled after being coughed, sneezed or exhaled by a fast moving person.

There were many limitations to this study. Mainly, the study was about droplets, not infectious particles, and none of the authors were medically trained. Many medical experts have responded that the study in no way addresses the risk of spreading infection. There are many more factors to consider. Droplets disperse much differently outside than inside and are subject to the effects of temperature, humidity and wind currents; all can significantly reduce or eliminate the ability of the virus to reach and/or infect another person. Finally, the work has not been peer-reviewed, something we require in the scientific world for anyone to make any serious claim about the results of anything. Anything less than that is just conjecture.

As SRCC’s resident doctor of epidemiology, I still strongly recommend that you ride solo or only with those with whom you cohabit. If for some reason you simply must ride with others, exercise extreme caution. Only ride with one or two people whom you’ve frequently ridden with before in order to reduce the risk of accidents. This will also make it easier to ride side-by-side or stagger. Choose quiet roads as they lower your chance of car/bike incidents. Stay out the hospitals as much as you can.

Keeping the number in your group low (one, two or three max) directly lowers the risk of transmission. It also helps avoid having to ride in someone’s slipstream. And riding in larger groups may not only be risky, it sends the wrong message to the rest of the community about cyclists.

So how far away is good enough to be safe and beyond the reception of someone’s virulent personal droplets? Scientifically, we simply don’t know. Obviously, the further apart the better, and certainly no closer than 2 metres. For a given distance, the above-referenced study indicates that side-by-side is less likely to lead to transmission than riding single file. No shit Sherlock.

Never forget why we’re doing this. We’re not doing this so we don’t get sick, we do this so we don’t get other people sick. And step one in that is: don’t get sick.

These days everyone needs to do their part. And when we’re seen, we need to be seen doing our part. Simply, group riding is verboten. Don’t be a douche, doctor’s orders.

Wash, rinse, repeat.

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