How wide is a bike lane?

What you see is not always what you get.

I was reading an article about bike lanes recently, which claimed that the newest bike lanes in San Francisco (on Kirkham Street) were 6 feet (183cm) wide, which is the new city standard.

It also claimed that most of the existing bike lanes in the city were 5 feet (152cm) wide, which I’ll admit, I thought was cracked. I ride in a lot of bike lanes in this city, and I would eat my helmet if they were all 5 feet wide. Time to take out the tape measure!

After stopping in various awkward places around my commute, I concluded that bike lanes are the opposite of trees: the older they are, the narrower they are.

  • On Arguello and Sacramento north of Golden Gate Park: 4 feet (122cm) travel width
  • New JFK bike lanes within Golden Gate Park: 5 feet (152cm) travel width
  • According to the article above, the new Kirkham bike lanes: 6 feet (183cm)–I didn’t measure

The protected bike lanes on JFK Drive rarely feel crowded.

My feeling is that the narrowest 4 foot lanes are by far the majority within San Francisco right now, although admittedly I don’t ride as much South of Market, and they’ve striped a lot of lanes down there in the last few years. If the lane has a marker reading “BIKE LANE” or a picture of an un-helmeted bike rider you’ve hit a 4 foot lane for sure, although some of them have been repainted with a helmeted rider. I would guess the odds of these lanes being restriped to a greater width are pretty slim. Most of the attention right now is rightly concentrated on creating new lanes and expanding the network.

Why does it matter? Two major reasons: car doors and traffic.

In the new JFK bike lanes, 5 feet of width is plenty: they’re right against the curb and cars park on the left, they’re protected from the door zone with a buffer zone, and so there is plenty of space for me to ride alongside my son, or for another rider to pass us.

In the 4 foot lanes in the city, and even some of the new 5 foot lanes things can get hairier.

At the dotted line, the cyclists move left and the cars turning right (if there were any) move to the right before heading into the intersection.

These lanes are primarily to the left of parked cars, and an opened door can easily cut the bike lane in half, giving a rider an effective width of a 2 foot (61cm) to 2.5 foot (76cm) travel lane. Dooring incidents are relatively low on weekdays as San Francisco drivers are conscious of bike commuters. Dooring incidents are rampant on weekends when out-of-towners drive into the city and leave their doors hanging open in the bike lanes for no apparent reason, maybe to air out their cars. It’s a mystery, and they get angry when we ask them, politely, to stop blocking traffic.

These lanes are also striped to merge at intersections, allowing cars to turn right and bicycles to move left, which is why San Francisco doesn’t have the right-hook issues that other cities do. As long as everyone signals it is a little complicated but works fine: when the line becomes dashed, turning cars move right and bikes pass them on the left to go to the front of the intersection. (Moving forward in the intersection is a safety move to prevent a car further back in queue from turning right in front of a bicycle moving straight, the dreaded right-hook.) But this merge dance results in cars blocking the right half of the bike lane: once again, the bike lane effectively narrows to half its width whenever a car is turning right. Cars can’t usually pull right up to the curb for a right turn as they would when parking, or they’d run over the corner and pedestrians, so they’re partially in the bike lane.

When a bus moves into the right lane for pickups or turns, it takes some guts (and a narrow bike) to move to the left as suggested when heading straight.

Why does this matter? Most bikes can effectively navigate a 2 foot bike lane, but cargo bikes like our Kona MinUte can be more problematic; the bags on the side hang out several inches when full, making the bike up to 25″ (65cm) wide. I prefer to keep them in the folded position while I’m riding even though they can hold less that way. Then the bike is 16″ (40cm) wide, which is no problem (or I can fill one but not the other.) Matt typically keeps both filled but is actively looking for a better replacement for the stock bags due to their width. Can you put FreeLoaders on a MinUte?

I also had real problems getting the Yuba Mundo through these pinch points when it was visiting. For a long time I couldn’t figure it out: long-tail bikes are basically the same width as other bikes and we were using the front Bread Basket for cargo, so we didn’t have the MinUte rear bag problem. Why was I feeling caught at intersections all of the time and forced to stop behind turning cars (blocking other bikes behind me)? I hated taking the lane from the bike lane when the kids were on deck; cargo bikes are slow to start when laden, and drivers understandably get a little annoyed when riders swing in and out of the bike lanes. And I was the only bike doing it.

I only recently realized that my issue was the Mundo’s Side Loaders. To keep heavy loads off the ground or carry bicycles or give kids a place to rest their feet, the Mundo has two bars sticking out from each side of the rear deck, so the frame’s total width is over 20” (51cm). If you add a pair of full GoGetter bags, the bike’s width increases to over 35” (90cm). I didn’t even have the GoGetter bags, and 20.5” isn’t that much wider than an ordinary bike, but it was changing the way I rode. And yet: I didn’t feel like the Bread Basket in front, at 19″ (48cm) was the problem, even though it was almost as wide. And Yuba notes that the Side Loaders are supposed to be no wider than the rider’s feet on the pedals. Was it just that I couldn’t see the wide load in back?

Why does it matter? We are trying to figure out a new family bike, and width is apparently an issue. Most family bikes and cargo bikes are much wider than an ordinary bike. My problem, even if it was just perceptual, was the same problem people have with child trailers in San Francisco: at 28”-32” (70-82cm) they’re often wider than the space available in the bike lane, and as a rider, you can’t see whether they’re going to make it through. We have an additional issue: no trailer on the market would fit through our narrow basement door, which when opened is just shy of 28″ wide.

Could I handle a wide bike in normal bike lanes, when I arrived at intersections where the lane is cut in half? Would it be easier if the load were in front where I could see it? These are San Francisco problems, but they’re real for us.


Filed under commuting, San Francisco, traffic

4 responses to “How wide is a bike lane?

  1. I was thinking about this yesterday especially when we rode 24.6 miles across town with three cargo bikes loaded to the gills with kids and stuff (and tiny bikes). Family Ride will have to comment because her bike was way more loaded than mine, but I think the Dummies managed surprisingly well through tight squeezes and the like. If I haven’t super stuffed the Freeloaders, I don’t feel but a few inches wider than a normal bike, and that’s just the little bit that the foot rests for the 2yo’s Yepp seat stick out. It’s fairly nimble that way.

    Maybe FR and I can do some bike lane investigating of our own here in Seattle.

    • I’d be interested to hear about the width of bike lanes in other cities. When I rode the Dummy I didn’t feel like it had any width issues, but I wonder if that would still be true when hauling kids’ bikes or if Wideloaders were installed. And I suspect width would be a real issue with the new Sidecar, although perhaps it would be worth it to carry a box spring!

      • My new WideLoader makes my Big Dummy wide! Actually, I can’t tell if the WideLoader is wide on it’s own, but when I put both balance bikes on the same side, with handlebars together, they stick out quite a bit. Narrow bike lanes are iffy and the sidewalk is a pain in this case. But with one balance bike on either side I feel very trim.

        I’d love a Sidecar! But I suspect that is strictly taking-a-lane kind of add-on. And har har har, my box spring carrying days are over.

  2. GRJim

    I’ve ridden my Xtra in the city a lot and am not entirely following what’s happening to you on the Mundo on the road but I kind of skirt the seams, if you will and don’t pay a huge amount of attention to the lines/lanes if it means I’ll be put in danger. BTW this is with one wideloader on the L pushed in a bit, so I’d say it’s a little wider than the Mundo side loader.

    Mind you I’ve been riding there for 20+ years; I think you’ll just get used to finding a golden thread through traffic while simultaeously getting used to the rear width.

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