Suicide Swerve

Last night, Ted and I discussed this unlikely report of a cyclist’s accidental death. The cyclist, 20 year old Justin Price, was riding to work in the shoulder when, according to witnesses, he suddenly swerved into the side of a passing tractor trailer. Although the truck driver, Kerry Williams, heroically tried to avoid Price, Price hit the truck. Price bounced off of the side of the truck, but he apparently didn’t have enough — police say Price swerved back to the truck again, after which he, sadly, perished after he ended up under the trailer.

Anybody who reads news accounts of road cycling traffic collisions frequently find mention of these inexplicable “suicide swerves,” in which the hapless driver is just driving along when that maniac on a bike inexplicably swerves right into the car.

Those who share the road with traffic realize what probably happened: the motorist passed with inches to spare, or they move over a little to pass but then merge right into the cyclist’s space on the road before the pass is complete. In either case, the results can be tragic for the cyclist, even if the cyclist did everything right.

Amelie Le Moullac was killed two weeks ago when, according to those with the windshield perpsective, she “swerved” into the side of a truck in San Francisco. The presumption of guilt on the cyclist has prompted local bike advocates heap heavy criticism on the SFPD for their cursory investigation. In Santa Cruz, the police reported a cyclist swerved into a passing gravel truck in 2007, when the accident reconstruction for the subsequent civil suit showed the truck driver likely hit the cyclist in this fatal collision.

Because these reports putting blame on the cyclist are so common, many people — Ted and I included — sardonically refer to these reports as a “suicide swerve.” A subset of these — the infamous “Single Witness Suicide Swerve” or SWSS — comes from the days of Usenet and possibly predates even that. The SWSS refers to a crash with a single surviving witness — the driver of the motor vehicle — who swears to a credulous investigator that the cyclist just swerved right in front of the driver. The presumption of guilt on the cyclist is reflected even in our traffic collision statistics, which show a majority of bike-vs-car collisions are caused by the cyclist.

During this online discussion, we discovered some people take exception to our use of the word “suicide.” Suicide is, after all, a serious and sensitive topic for many people, and some thought the term was used as click bait. We explained the usage, however, and our friends understood. Most cyclists probably don’t have a death wish, but just want to get from point A to B. The idea that cyclists intentionally swerve into the sides of passing trucks is, frankly, offensive, yet many investigators seem to believe that’s how we behave.

Yes, there’s stupid behavior that will kill you, and I’ve seen plenty of it in my part of California. I’ve watched cyclists try to squeeze into a too small space on the road, and I’ve occasionally been the idiot party myself, both on bike and in the car. I’d wager, however, that many “swerves into traffic” are instances where a passing driver doesn’t have room to pass, or passes with only inches to spare while expecting superhuman agility on the part of the cyclist to hold his line.

I applaud the San Francisco Bicycle Coalition demands for better investigations of bicycle fatalities in their city.


  1. It’s a tragic problem, this is of the reasons I have a bike camera, mostly to document aggressive drivers and incidences similar to this one where someone passes, then swerves into the bike lane, if there is one, and forces a difficult choice for a cyclist. I’ve been hit by trucks pulling lawn trailers at least three times, my left arm has a repeating scar that servers as a metric reminder to me, by the time it heals it’s overdue for another accident.

  2. I wonder how much of the “swerve” is actual motion due to the slipstream of a vehicle that’s passing too close (either a direct effect, or the cyclist losing his or her balance due to it), and how much is the perception of motion by witnesses because the motor vehicle (especially a truck) is so much larger than the cyclist, so witnesses think that the larger vehicle is going straight.

  3. I think it must be partly due to the fact that you have to balance your weight and steering slightly to the right to turn left when going straight and with the vehicle being so close this is enough to clip you and pull you in. Either way it’s probably a lot of selective memory if they’re even looking

  4. Even the most seasoned cyclist will startle a bit when a car blows by too close. I try to “internalize” my startles and avoid reacting physically with a swerve or wobble, but depending on how sudden and scary things are, nobody can just fully clamp that stuff down all the time. I wonder how many of these “swerves” were commited by cyclists who had just had the crap scared out of them? When its a matter of inches…

  5. Good point about the “perception of motion.” Cars and trucks normally wobble some on the road. They’ve navigating a seven to eight foot wide vehicle down a 14 foot lane, so weaving 12 to 24 inches to either side isn’t that remarkable. A cyclist moving four inches to one side to avoid broken glass or a drain, though, is perceived as out of control and swerving all over the lane.

    Related to stop signs, too: Cars traveling at 45 MPH slowing to 15 MPH at a stop sign or right-turn-on-red is law abiding, but a cyclist traveling at 15 MPH slowing to 10 MPH for the same motion is a dangerous scofflaw, when in fact both are breaking the law.

  6. As Amelie’s mother may I say that your comments about our beautiful daughter possibly committing suicide are not only false, they are cruel and insensitive to her family that grieves. Please have some human decency and remove her name from this posting.

  7. Ms Jewitt, I feel horrible that I caused you unnecessary grief. The point of this essay is the exact opposite of what was apparently conveyed. In no way did I mean to suggest that any of the cyclists risked their own lives. Instead, I intended to highlight the common attitude on the part of law enforcement that the cyclists, including Ms Le Moullac, are responsible for these collisions, when in fact the police often don’t investigate any of these collisions. As I note in the conclusion, I applaud the San Francisco Bicycle Coalition in their efforts to bring the responsible parties to justice.

    I apologize for the misunderstanding and have rewritten the essay to clarify my meaning. You have my sincere condolences.

  8. Depending on wind conditions, speed, and proximity of the passing vehicle the observation of Brian Ogilvie holds a lot of merit. On windy days a passing truck creates a large ‘shadow’ or ‘lee’ when it passes. A cyclist compensating for a crosswind which is then suddenly removed will veer in the direction in which he was compensating … It would be like leaning against something and then having it pulled away. Add the slipstream effects of speed and or low pressure zone of an open undercarriage, which are significant for large trucks passing too close and you have the potential for tragedy. I’ve experienced this myself. Luckily for me, it has only happened on a wide shoulder where I’ve had enough space to react.

  9. When the truck or bus has almost overtaken the cyclist, the air they displace tends to push lighter vehicles (like bikes, but you feel it in a car too) to the side. The natural response is to steer back toward the middle of the road. As the big vehicle passes by, so does the displaced air, and there’s a suction effect which pulls the left-steering / leaning cyclist toward the bigger vehicle. If the truck is passing close by, there’s not much time for the cyclist to re-correct and steer away. And, if the truck moves right too soon, cyclist will get clipped by the side or back corner of the truck or trailer. Big vehicles, and much faster ones (pushing more air to the side) need to pass further away.

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