Bike to Work Day is May 17. The cold winter is over and the hot summer isn’t here yet, so it’s time to leave the old gas-guzzler/carbon-emitter behind and mount up. The first year you commute by bike, you’ll lose 13 pounds.

Considering how obsessed with weight loss Americans are, you’d think that would be a persuasive argument. But researchers have found no evidence that feel-good occasions like Bike to Work Day are converting people to bicycle commuting.

I have no evidence that my columns are, either, and I stopped writing about biking years ago. It was just too depressing.

The latest downer was when Lime Bike and Ofo pulled their rent-by-the hour bikes off the streets of St. Louis, declaring the venture a failure after just a few months. Only electric scooters are left.

Foraging online, I found more bad news. The best estimates are that 100 million Americans ride bikes, but fewer than a million ride them to work. For the rest, biking means an occasional Saturday in a park or on a trail.

Most of the research on bicycle usage relies on a single question in the census, which can be interpreted in various ways. But recent studies tend to agree that biking to work is declining. After a rise circa 2010 that enthusiasts got very excited about, the number of cycle commuters began to fall in 2014 – some say by as much as 4.7 percent per year.

Locally, we’re not seeing such a decline – but that may be because the numbers were already so low. In bike commuting, Missouri comes in 44th among the 50 states and District of Columbia. It’s important to mention D.C., since it comes in first.

Why are people biking less? Partly it’s economics: gasoline is cheap. Partly it’s politics; the Trump administration’s policy on global warming is to ignore it. But researchers say these are trivial factors. There’s one big reason most people won’t bike on the street: they’re afraid of being hit by a car.

Admittedly, that’s a risk. It’s difficult to establish the relative dangers of biking vs. driving; the numbers are all over the place. But obviously you’re safer wrapped in two tons of steel than perched on a bike.

Still, I think there’s something more complex going on here. It isn’t just the physical risk. People shrink from exposing themselves to the hostility of drivers.

Here we enter contested territory. When I wrote a column protesting about motorists killing cyclists, I received a letter from an indignant motorist, saying cyclists had only themselves to blame. They were reckless law-breakers. He seemed to want me to be more balanced and write a column about motorists killed by cyclists.

Which I would do – if there were any.

According to social scientists, my correspondent’s beliefs are widespread, and traceable in part to the fact that cyclists are scarce and therefore conspicuous. Of course, some cyclists behave recklessly and flout the law. Some drivers do, too. But a single cyclist pedalling past a stop sign is much more visible than a dozen drivers speeding to beat a yellow light.

One psychologist made an analogy between the way drivers talk about cyclists now and the way whites talked about blacks when society was more overtly racist. Due to a quirk in the prejudiced mind, whites generalized any fault they saw in an African American to the whole race. (“They’re all like that.”) Naturally, they minimized the faults of whites.

In the same way, many drivers imagine they’re all faultless and cyclists are all irresponsible outlaws.

Considering that when people get on a bike and go out on the street they join a minority group and put their lives in the power of a majority who despise them, you can understand why fewer people are mounting up.

What would change their minds? Poll respondents said they’d be more likely to bike if infrastructure separated them from car traffic. They weren’t talking about those “bike lanes” St. Louis is so fond of. Paint stripes have negligible protective power.

Truly protective infrastructure would be expensive, and I doubt city governments will adopt an “if you build it they will come” policy.

But here’s the good news: we already have infrastructure that separates cyclists from car traffic. St. Louis has more closed streets (285) than any other city. The inner suburbs also have many. Whether the barriers are the gates of private places or the “Schoemehl pots” of humbler neighborhoods, they bar motorists and let cyclists through.

I biked to the office for the last 25 years of my working life, and I continue to bike on errands nearly every day. I’m almost always able to find an alternate route on residential streets where cars are few and slow-moving.

Try biking – you’ll like it. One last word of encouragement: most drivers aren’t as mean as you think.