Scott Simon’s bio on the NPR website describes him as “one of America’s most admired writers and broadcasters,” and it’s tough to argue with that. As a Peabody-winning journalist with decades of experience, Simon’s credentials are unimpeachable, and as the Saturday host of Weekend Edition, he regularly shows himself to be all the things you want a radio host to be: thoughtful, avuncular, well-informed, and above all, smart.

Simon also has one and a quarter million followers on Twitter, and last Thursday morning, he asked them this:

Now, you may have had this very thought, after watching someone on a bike blow through a red light, try and lane split through moving traffic, or do something similarly irresponsible. As Simon points out in a follow-up tweet, it happens all the time.

The problem, of course, is that no matter how egregious their behavior was, the three people he observed don’t indicate that “cyclists consider themselves above the law,” any more than a pair of jaywalkers prove that pedestrians are morally opposed to crosswalks. It also takes the very broad problem of traffic violations and limits it to a single minority, ignoring the millions of car and truck drivers who flout the law every day, not to mention those scofflaw pedestrians.

What Simon did in this pair of tweets was overgeneralize about a large group based on the behavior of a few members, and then tie that group to another member with a lot of bad press—two demonizing tactics that’ve been employed pretty much forever, to attack groups ranging from corporate lawyers to Asian drivers to welfare recipients.

Numerous replies pointed out as much, the most entertaining coming from author Eben Weiss, who writes a popular long-running blog out of New York City called BikeSnob:

The rest of the exchange consisted of sympathetic followers favoriting and retweeting Simon’s posts, others responding in passionate agreement, and dozens more drawing attention to its obvious fallacy (in a generally civil tone—Weiss’ snarky retort was about as combative as it got). Simon followed up several more times over the course of the day, appearing at first defensive, then dismissive, and finally a bit chastened and almost conciliatory.

Now, there’s nothing unusual about this kind of bikers vs everyone drama, especially on the Internet: browse the comments section beneath a bike-related article on almost any broad-reaching publication, and you’ll find that few topics besides Israel, healthcare and gun control stir up as much debate.

What’s remarkable is that Simon should’ve known better. An experienced reporter with a sterling reputation for fairness, he’s one of the last people you’d expect to engage in this sort of stereotyping. And yet something made it OK for him to veer from fact into conjecture when talking about some people riding their bikes, in a way that would’ve been unimaginable in describing a professional, economic, ethnic or gender group.

After 15 million miles traveled, the Citibike program has still caused not a single fatality for either pedestrians or riders.

This exception is something I stumble across regularly though, in the media and in everyday life. Delia Ephron, the celebrated screenwriter of “You’ve Got Mail” and producer of “Sleepless in Seattle” was so perturbed by New York’s new Citibike bikeshare system last October that she wrote a 1000-word opinion piece for the New York Times, complaining that “these bicycles have made walking around the city much scarier.” It’s a bold statement, completely at odds with the evidence—as of last month, after 15 million miles traveled, the Citibike program has still caused not a single fatality for either pedestrians or riders, and fewer than 30 serious injuries, while helping to improve the overall safety of the city’s streets.

A similar bikeshare system has been proposed here in Portland, but was vocally opposed in 2011 by city commissioner Amanda Fritz, who cited the “unsafe behavior” of existing cyclists as a reason to avoid anything that might put more of them on the streets.

Even my mom has gotten in on the act, complaining several times of the menace that bicyclists pose to the citizens of Santa Barbara, where she lives. As evidence, she described once witnessing a pack of seven men on bikes, speeding down Alameda Padre Serra at 30mph in the dark, and being struck with terror, despite the fact that hundreds of cars travel that same stretch of road day and night at 35 or 40, posing a vastly greater threat.

In each of these cases, a thoughtful, intelligent observer is prodded by a mix of fear and anger to give an alarming anecdote more weight than an abundance of evidence, or even common sense. On a street carrying thousands of 3000 pound vehicles a day at 40mph or more, we focus our fears on the handful of 30 pound vehicles moving half that fast.