To cyclists once bedeviled by pushy, impatient and dangerous drivers on Valencia Street, changes in the past year are stunning.

Ten months since city transportation officials shifted parking and added posts to gird cyclists from traffic, cars have all but stopped encroaching on the green bike lane that threads along Valencia between Market and 15th streets, according to data released by Mayor London Breed’s office Friday.

Trucks no longer use the bikeway as a loading zone — reports of illegal loading dropped from 159 in October of last year to two in May of this year. And cyclists can all but stop worrying about getting hit by a car door swinging open. Instances of bikes brushing up with cars in the middle of a block, where the risk of “dooring” is highest, have decreased by 95%.

The numbers show that cyclists and motorists both embrace the improvements, or at least abide by them. Ninety-eight percent of bikes observed on the corridor were in the buffered zone, and in the mixed areas where cars and two-wheeled devices interact, 84% of drivers yielded to bikes.

“The data now backs up what we knew to be true — commonsense safety improvements dramatically reduce the risk of collisions and save lives,” Mayor London Breed said.

She touted the city’s new “quick-build” policy that allows San Francisco Municipal Transportation Agency to cut through the bureaucratic morass and immediately add buffers or paint to dangerous streets.

In May, Breed told the SFMTA to double the pace of protected bike lane construction and add 20 miles in the next two years. Many roads may come to resemble Valencia, with a striped path for bicycles next to the curb and parking moved over one lane, to add an extra buffer.

“I really like it,” said Dalton Corbin, who was riding a Lyft rental bike along Valencia near Duboce Avenue on Friday afternoon. The green lane was buzzing: Parents cruised by with toddlers in kid seats. Mountain bikers hunched over their handlebars, weaving around Uber Jump bikes and electric scooters.

Jamal Gibbs rode a skateboard, clutching an iced coffee in a plastic to-go cup.

“I respect this bike lane,” said Gibbs, an Outer Mission resident, adding that he shares the path more or less peacefully with cyclists. “It gives us all a place to be,” he said.

Others weren’t convinced that engineering alone will prevent crashes, or fully shield bicycles from traffic. Some say that motorists will continue to squeeze into the bike lane unless SFMTA and the Police Department step up enforcement.

“The cars, they still stop in the lane,” said Eduardo Poot, who was riding a Trek mountain bike north on Valencia Friday.

Yet the executive director of San Francisco Bicycle Coalition praised Breed and the SFMTA for accelerating construction of the city’s bike infrastructure. In addition to the Valencia Street strip, SFMTA staff recently finished a 1-mile protected bicycle lane on Seventh Street, between Townsend and 16th streets.

The success of this first Valencia Street segment, dubbed the Street Pilot Safety Project, “makes a great case that the city needs to address the rest of Valencia Street as soon as possible,” said Brian Wiedenmeier, executive director of the bicycle coalition. The popular north-south route extends 2 miles through a bustling Mission District corridor of bars and restaurants.

Wiedenmeier and other coalition members test-ran the latest addition to the project on Thursday — a new bike traffic signal at Valencia and Duboce Avenue. It allows bikes to pass through the intersection one at a time, free from cars.

Rachel Swan is a San Francisco Chronicle staff writer. Email: rswan@sfchronicle.com Twitter: @rachelswan