Lane width and vehicle width

A 2011 Toyota Camry (what I’d consider a typical mid-size sedan) is 71.7” inches wide. That’s just a hair under 6 feet, so for the sake of simplicity let’s just use 6 feet. Large SUVs are about 6.5’ wide. That’s just the vehicle dimension. What’s not taken into account is the side-view mirrors. Again, for simplicity and to err on the safe side, I’ll say that the mirrors are in the vicinity of a foot wide each. This adds approximately 2 feet to the width of these cars- therefore a mid-size sedan is now about 8 feet wide, and a large SUV is about 8.5’ wide. When we get to extremes, a HUMMER H2 is 81.2” wide, which is approaching 7’ wide. Typically the larger the vehicle, the larger the mirrors.

No matter what you drive, understanding the full width of your vehicle is critical to passing a bicyclist safely. The mirrors of many vehicles are very close in height to the widest point of a bicyclist, which is the handlebars. If you are towing a trailer, it’s also important to remember that your trailer may be wider than your vehicle, and that with a trailer your passing distance increases by the length of the trailer!

How does this affect a bicyclist? A typical travel lane on a 2-lane road is about 11 or 12 feet wide. Sometimes they are a little narrower, but 12 is about the most you’ll find on any road with designated lanes. Again, erring on the safe side a pair of wide flat handlebars are about 28-30” wide.

Most experienced riders (and there's no good way to tell an experienced rider from an inexperienced rider when approaching from behind) ride about 1-2 feet to the left of the edge of the pavement or the white line (and it's difficult to ride a perfectly straight line.) The reasons for this are many- the edge of the pavement is often where glass collects, drainage grates may be located, or where there is broken pavement or gravel from driveways. Riding further into the lane also increases visibility, as a motorists behind should be able to see us better and earlier if we're in their line of sight.

So, let’s do some math:

A cyclist riding 2 feet from the white line takes up 39" (3.25') of designated lane- the handlebars being the widest point, and the wheel being centered between the 30" handlebar. 2' + 1.25' = 3.25'

A typical sedan takes up about 8' of lane.

Now for some laws: In Virginia, the law states that you must give 2' between your vehicle and the bicyclist (we're trying to make this 3', but so far have been unsuccessful.) In Maryland and many other states, the law states that you must give 3'.

Back to the math- if a lane is 12' wide (again, a maximum), a bike takes up 3.25', a mid-sized sedan takes up 8', and you should give a minimum of 2' clearance: 8+3.25+2 = 13.25. The narrower the lane, the more critical the numbers. In other words, to pass a bicyclist with minimum safety, you should at least be over the lane lines with the driver's side tires.

To pass a bicyclist without giving enough room for them to safely navigate an obstacle, or to make an attempt to pass a cyclist without being clearly in another lane (oncoming or same-direction) is unsafe and extremely dangerous for a bicyclist.