Since the gyms are closed, my wife and I have been taking a six-mile walk around Silver Spring early in the morning, physically and temporally distanced from others. Around downtown, there are little metal bars spaced out on surfaces of ledges, concrete, stone and wood, some appropriate as benches, some too low to sit on. They don’t seem to be there to divide the spaces up into separate seats but I can’t figure out what other purpose they might have. I hope that you can marshal the resources of your Answer Man team to find out.

Scott M. Paul, Silver Spring

Our story begins in 1998 in Southern California, in San Diego County, to be exact. That’s where Chris Loarie’s brother was a police officer. While on his beat, Loarie’s brother heard from a church pastor who worried that people skateboarding on church property were going to wind up crashing through one of the windows.

The reason: The skaters would build up speed on the flat pavement, then launch their boards onto raised surfaces like ledges and walls. The pastor felt it was only a matter of time before a skater or his board went flying.

How to stop this?

“I decided I would take a run at designing a product,” said Loarie, who at the time worked for a company that made electric vehicles and before that worked at firm that made those shopping carts with a wheel that locks up when you take it off store property.

What the skaters were doing is grinding — a basic trick in street skating. It starts with a move called an ollie. That’s when the skater leaps up, the board stuck to the bottom of his feet as if by magic. He brings the underside of the board or its trucks — the axles bearing the wheels — down onto a ledge or railing then slides along it.

There are as many variations of the grind as there are orchids in the rainforest — they have names like 50-50 grind, backside 50-50 grind, nose grind, crooked grind.

All share one element: the grinding of the board across a horizontal surface.

If it’s your surface — your ledge, wall, railing or other architectural element — you may not want it to be grinded upon, as the skateboard can damage the stone, concrete or metal. That’s what Loarie was trying to prevent.

Being in San Diego County, there were plenty of places for Loarie to watch skateboarders in their natural habitat. He worked at his kitchen table, carving model parts out of foam. What he first came up with was a plastic disk that could be formed to the contour of the edge and glued down. The idea was to deprive skaters of enough room to gain grinding momentum.

The plastic disks were an inelegant solution — and not a very durable one. Loarie said skaters would just chisel them off and get back to grinding.

“There was definitely some trial and error,” Loarie said. He eventually developed a metal product that is anchored into the ledge surface with pins and secured with epoxy. His company, Skatestoppers, sells devices in various shapes, sizes and materials. Some are plain, with a clean, tapered art moderne look. Others are decorative, shaped like seashells or oak leaves.

Loarie recommends they be placed about three feet apart.

“We’ll still get some who put them in at eight feet or 10 feet apart,” he said. “We just tell them, ‘Hey, you might not want to bother putting them down.’”

Today, Skatestoppers dominates the market, along with SkateBlock, a similar product from a Seattle company called Ravensforge Coneg.

As you’d expect, these little speed bumps are not popular with skaters.

“There used to be a phrase: The world is your skate park,” said Mike Mapp, a former professional skater. “You throw the Skatestoppers in there, it kind of gets sour.”

Mapp owns Ramptech, a Woodbridge, Va., company that builds and sells ramps, half-pipes and other skate-at-home products. Most of the products incorporate a rail for grinding.

“Skatestoppers are hated by skaters, and the guy who invented them, well . . . whatever,” Mapp said.

There will always be animosity between those who seek to grind and those who seek to stop the grind. Loarie said he’s been in business long enough that some of the people ordering his product were once on the other side of the divide.

Said Loarie: “I have former skateboarders who tell me, ‘I can barely stand to do this, but they just ruined my work and I’m accountable.’”

Twitter: @johnkelly

For previous columns, visit washingtonpost.com/john-kelly.