A man approaches a bicycle, handheld electric saw at the ready. He powers it on, starts to drill, and is shot in the face with a noxious spray that makes him vomit uncontrollably. This is the dream of the inventors of SkunkLock.

“Basically we were fed up with thefts,” said Daniel Idzkowski from San Francisco, one of the inventors of SkunkLock. “The real last straw was we had a friend park his very expensive electric bike outside a Whole Foods, and then went to have lunch and chat. We went out and his bike was gone.”

Idzkowski’s friend had used two locks, each $120, whose inability to stop a thief outraged him. “I blurted out, ‘why didn’t it blow his balls off?’”

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He eventually landed on a less violent and more legal innovation. “I realized there really is no solution to this problem,” he said. “The biggest problem in this industry is that people don’t know that the lock that they bought for $20 is absolutely worthless. It costs at least $100 to have at least somewhere close to where you can at least curb the chances of a thief wanting to steal your bike.”

With the right tools, Idzkowski said, a thief could cut through most locks in less than a minute. Thieves, he said, “talk in seconds: a 15-second bike, a 20-second bike, and it goes up to 30-60-second bikes, with Kryptonite locks that require two cuts, each about 25 seconds”.

With his co-inventor, Yves Perrenoud, Idzkowski created a U-shaped lock of carbon and steel with a hollow chamber to hold one of three pressurized gases of their own concoction, including one called “formula D_1”. When someone cuts about 30% of the way into the lock, Idzkowski said, the gas erupts in the direction of the gash.

“It’s pretty much immediately vomit inducing, causes difficulty breathing,” Idzkowski said. “A lot of similar symptoms to pepper spray.”

The inventors have not yet tested the device on an actual would-be thief, but have tested it on themselves and volunteers at distances of two feet (60cm), five feet, 10ft and 20ft. “At two feet it was pretty bad. It was absolutely vomit inducing in 99% of people. At five feet it’s very noticeable and the initial reaction is to move away from it. At 10ft it’s definitely detectable and very unpleasant.”

Bike thieves have had virtually free rein around San Francisco and the Bay area for years, stealing thousands every year, turning warehouses and underpasses into chop shops, victimizing residents and city officials alike. Last year the thefts prompted a 20/20 news segment, and city police estimated that eight in 10 bikes in a chop shop are stolen. Anecdotal evidence supports the statistics: on Thursday, a Mission resident told the Guardian that thieves had recently strolled into his garage and cut three bikes from their locks on the wall.

Idzkowski said their chemical had passed compliance tests and was legal, and that its variants were designed to be compliant according to the varying rules of 50 states, major cities and EU nations.

He admitted the lock was not foolproof. It could be picked, for instance – and many bike locks can be picked with something as simple as a cheap plastic pen. Idzkowski argued, though, that the widespread use of advanced disc-cylinder tumbler locks, including in the SkunkLock, meant it might take even skilled lockpicks up to half an hour of tinkering – long enough to draw attention.

A thief could also simply return to the spent lock, though Idzkowski insisted this would not be easy, because the noxious spray clings to skin and clothing.

“You’re basically just puking on yourself the entire time,” he said. “They could change all their clothes, shower, if the bike is still there come out and cut the remaining 75% of the lock. You can’t prevent a theft 100%, so that’s why we call it a deterrent lock, not a solution.

“All you have to do is be better than the bike across the street.”

Like many Bay area entrepreneurs, the SkunkLock creators are crowdfunding for their future. Pledging $99 to their Indiegogo fund promises a customer their own SkunkLock in June 2017, pending risk assessment by their legal team.