It’s not entirely clear how the bicyclist — eco-friendly and healthy — became such a divisive symbol.

Drivers honk at cyclists, pedestrians yell at them, and the angry, militant cyclist flipping everybody off has become a cliche. It seems there’s anger on all sides.

The textbook case is down in Woodside, where they’ve been fighting the two-wheel wars for over a decade. It began when someone sprinkled carpet tacks on weekend bike routes, including scenic, redwood-studded Kings Mountain Road, a winding, two-lane, shoulder-less cycling favorite. It’s been on-and-off guerrilla “a-tacks” ever since.

“Putting tacks up there has been going on for 10 years,” said Mike Jacoubowsky, a lifelong cyclist and longtime owner of the Chain Reaction bike store in Redwood City.

In the most recent incident, a few weeks ago, eight cyclists incurred flat tires after someone took the time to embed the small nails, point up, near the summit to Kings Mountain Road.

In response, Woodside attorney Walter Cook, an avid cyclist, crowd-funded a $10,000 reward to catch the culprit. Cook started putting up posters in Redwood City on Friday.

“What’s curious about that is the signs come down as fast as they are put up,” he said. “Somebody’s taking them down.”

And there we have it. There’s more to this than just being upset at a bike rider whizzing past a pedestrian. This ties into the simmering undercurrent of disapproval of the cycling trend and what it all means. You can see it whenever we write about bikes and problems.

Cyber-rage mounts

Online reader reaction snowballs from people griping about cyclists going too fast to “those idiots at Critical Mass” who blow stop signs. Eventually, someone writes, “Bicyclists should follow the same laws as cars,” and the next thing you know, the entire cycling community is under attack.

Let’s look again at the Woodside kerfuffle. When the local paper, the Almanac, did a story about Cook’s efforts to catch the carpet tack vigilante, it triggered a whole string of online comments, including one that is typical of the debate.

A commenter identified as “La Hondan” wrote, “I think this is a symptom of a deeper community problem. This is not about bicyclists, motorcyclists, car drivers, horseback riders or pedestrians. It’s about courtesy and civility ... it is all about “Me! Me! Me!” and everyone else be damned.”

Forty-six readers took the time to “like” the post on the site. But that was topped by another posting by someone who identified himself as “Mr. Tackman.”

“I didn’t dump tacks, but I can see why someone might have, and they may not be as deranged a maniac as you may think,” he wrote, adding, “People do live where you ride, and I know their frustration with the explosion of cyclists in the area.”

Justifying vandalism? That sounds pretty extreme, yet 70 readers “liked” that posting.

“I thought the choice of names was provocative,” Cook said about the posts. “But Mr. Tackman’s comments clearly struck a nerve.”

Jacoubowsky thinks the divisiveness isn’t much different than what happens in our nation’s capital.

“We have become an increasingly polarized society,” he says. “We only pay attention to the far left or the far right. The centrist doesn’t get any print.”

Annoyance with racers

Granted, even Cook and Jacoubowsky admit that cyclists can be their own worst enemy. Kings Mountain Road attracts bike racing clubs.

“The big racing clubs are part of the problem,” Cook says. “If you are riding with a racing team and you’ve got some guy out front that is hammering, you’re doing all you can to stay up with the group. If you get stuck at a stop sign, you’re going to be lost to the group.”

Street racing on public roads is always a bad idea — bikes, cars or skateboards. But we all need to take a deep breath, and remind ourselves that the vast majority of people riding bikes aren’t psycho-cyclists.

“There’s a lot of angst down here about bike riders,” said Cook, who belongs to a club of mostly older riders who observe traffic laws. “I feel like if you get caught in a (car) backup it is no big deal. But if bikes hold you up, call out the National Guard.”

The reality is that cycling is a huge, growing social trend. San Francisco’s Municipal Transportation Agency says the number of people biking in the city has doubled since 1996 and is expected to grow another 157 percent by 2020.

And this isn’t just Millennials. A National Household Travel Survey released in 2014 showed that ridership by people between 60 and 79 has increased 320 percent. (There was also a rise in visits to the emergency room by older cyclists, by the way.)

So here’s the point. We understand that it’s a scary situation when cyclists roar down a narrow road at high speed, cross the yellow line and scare drivers. But most riders aren’t doing that.

Bike riding is here. It’s getting bigger, not smaller. It’s time to accept that and drop the social hand-wringing. Sometimes a bike is just a bike.

C.W. Nevius is a San Francisco Chronicle columnist. His columns appear Tuesday, Thursday and Saturday. E-mail: cwnevius@sfchronicle.com Twitter: @cwnevius