A sharrow is a pavement marking that shows a bicycle symbol topped by two chevron arrows, painted directly in a travel lane shared by cars and bikes. The name is a blend of “share” and “arrow.” Unlike a bike lane, which gives cyclists their own dedicated strip of road, a sharrow simply signals that cyclists belong in the lane and reminds drivers to expect them there.
What a Sharrow Looks Like
The marking is hard to miss once you know what to look for: a white bicycle icon with two stacked chevrons (like a sergeant’s stripes) pointing in the direction of travel. Cities typically paint sharrows in a repeating pattern every few hundred feet so both cyclists and drivers encounter them regularly.
Placement follows federal guidelines from the Manual on Uniform Traffic Control Devices. On streets with parallel parking, the center of the marking sits at least 11 feet from the curb. That distance is deliberate. It positions the symbol outside the “door zone,” the roughly 4-foot swing radius of an opening car door that is one of the most common causes of urban cycling crashes. On streets without parking where the outside lane is narrower than 14 feet, the marking center goes at least 4 feet from the curb or pavement edge.
What a Sharrow Is Supposed to Do
Sharrows serve two goals. First, they guide cyclists toward a safer lateral position in the lane, pulling riders away from parked cars and gutters. Second, they alert drivers that the lane is shared, which should theoretically encourage more cautious passing.
A sharrow does not create a bike lane. It does not restrict motor vehicles from the space. It does not change the speed limit. It is, in practical terms, a reminder painted on asphalt. Cyclists riding on a sharrow-marked street have the same legal right to use the lane as any other vehicle, but that right typically exists whether or not the sharrow is there. Most state traffic codes already allow cyclists to occupy a full lane when the lane is too narrow to share side by side with a car.
Where Sharrows Work Best
Sharrows are generally considered appropriate only on low-speed, low-volume streets. The National Association of City Transportation Officials recommends that streets designed for comfortable shared use have motor vehicle speeds at or below 25 mph and total traffic volumes at or below 3,000 vehicles per day. The most comfortable shared streets go further: target speeds of 20 mph, volumes of 500 cars per day, and no more than 50 vehicles per peak hour. That works out to fewer than one car per minute passing through.
On busier or faster roads, sharrows become increasingly inadequate. When traffic volume climbs above a few thousand vehicles daily or speeds exceed 25 mph, cyclists need physical separation, whether that’s a painted bike lane, a curb-protected path, or a fully separated trail.
The Safety Problem With Sharrows
Sharrows are one of the most debated pieces of cycling infrastructure because the safety evidence is not encouraging. A study published in the journal Safety examined bicycle injuries caused by motor vehicles across different types of infrastructure. Painted bike lanes reduced injury risk by nearly 90% compared to streets with no cycling infrastructure at all. Physically protected paths (those with a curb or barrier between bikes and traffic) were associated with 23% fewer injuries. Sharrows, by contrast, were linked to worse outcomes: injuries near sharrows were roughly twice as likely to be moderate, severe, or critical compared to streets with no bike markings at all.
That finding surprises many people. How could a marking intended to improve safety be associated with more serious injuries than having nothing? One likely explanation is that sharrows create a false sense of security. Cyclists may feel entitled to space that drivers don’t actually yield, or cities may install sharrows on roads that really need protected lanes, checking a box for “bike infrastructure” without providing meaningful protection.
Motorist Passing Distance
An FHWA evaluation in Chapel Hill, North Carolina, measured how close drivers passed cyclists before and after sharrows were installed. On downhill sections, the average gap between a passing car and a bicycle shrank by 7 inches after the sharrows appeared, dropping from about 85 inches to 78 inches. On uphill sections, the gap stayed roughly the same, changing by just 1 inch. Overall, drivers passed about 3 inches closer after the markings went in. The researchers found no evidence that sharrows encouraged drivers to give cyclists more room.
Sharrows Compared to Other Bike Infrastructure
- Sharrow (shared lane marking): Paint on a shared lane. No physical separation, no dedicated space. Lowest cost, weakest safety evidence.
- Painted bike lane: A striped lane reserved for cyclists, typically 5 to 6 feet wide. Associated with up to 90% fewer injuries compared to unmarked roads in some studies.
- Protected bike lane: A bike lane separated from traffic by a physical barrier like posts, planters, or a raised curb. Provides the highest level of comfort and is associated with fewer and less severe injuries.
- Shared-use path: A completely separate trail for cyclists and pedestrians, away from the road entirely.
The gap between sharrows and even a simple painted lane is enormous. If you’re a cyclist choosing a route, a street with a painted bike lane is measurably safer than one with sharrows. A protected lane is better still.
How to Ride on a Sharrow
If you’re cycling on a street marked with sharrows, the most important thing is your position in the lane. Ride over or near the sharrow marking itself rather than hugging the curb or weaving close to parked cars. On a street with parallel parking, that means keeping roughly 11 feet from the curb, which puts you well outside the door zone. This position also makes you more visible to drivers approaching from behind and discourages dangerously close passes.
You may feel pressure from drivers to move to the right, but on a narrow lane (under 14 feet wide), there is not enough room for a car to safely pass you within the same lane regardless of where you ride. Taking a position near the center of the lane, often called “taking the lane,” forces drivers to change lanes to pass, which actually results in a safer passing distance than squeezing by in the same lane.
If you’re driving and encounter sharrows, the marking is telling you to expect cyclists ahead and to change lanes when passing, just as you would for any slower vehicle. The sharrow does not give you permission to pass closely within the same lane.