In most of San Francisco’s bike lanes, people are forced to ride between parked cars and moving cars. The looming threat of opening car doors and cars entering the bike lane is unsettling enough to keep many San Franciscans from riding a bike at all.

But take the car parking out of the equation, and that same 5- or 6-foot wide bike lane can feel immensely safer. That difference is apparent at construction sites like the current one at 1844 Market Street, between Octavia Boulevard and Laguna Street, where the north-side parking lane has been replaced by a fence separating the walkway and the bike lane. Suddenly, climbing the hill towards the Wiggle has become a less harrowing experience — at least until the parking comes back.

At another construction site, half of the northbound bike lane on Valencia Street underneath the Central Freeway was recently occupied by a utility ditch, with the bike lane running along the pavement’s remaining edge. Parts of the parking lane are closed to drivers. This case is probably more subjective to the rider, but I actually felt better riding in a skinnier bike lane along the edge of a small cliff compared to riding in between cars (the space occupied by the ditch is normally the door zone, anyway).

It goes to show how a bike lane’s quality can vary widely based on something as simple as its alignment. Even without physical separation from motor traffic, I would hazard that a bike lane striped along a curb feels comfortable for a much broader demographic than one placed in the door-zone.

Take some recent examples of new bike lanes in San Francisco: the buffered bike lane on Eighth Street is about 11 feet wide, but because it’s subject to frequent incursions by cars (and runs on a street with heavy motor traffic), it certainly doesn’t feel like a dedicated space safe enough for anyone 8 to 80 years old. (There is a long-term plan to convert it to a parking-protected bike lane.)

Meanwhile, parts of the new bike lanes on 17th and 23rd Streets are curbside. Perhaps Streetsblog commenters who use them can attest: How does your bicycling experience change when you don’t ride next to the door zone?