The U-lock that fell to a Bic pen
A woman walked into Bicycle Revival in Cambridgeport, Massachusetts one day in 1971 with a stolen bike and an idea. She’d been thinking, she told the mechanic, about using a large block of aluminum bent into a U-shape — something thick enough that no hacksaw could get through it quickly. The mechanic’s name was Stan Kaplan, and he spent the next several months turning her sketch into a product.
Kaplan’s refinements were practical rather than showy. He dropped the aluminum for flat steel bar stock, which resists bolt cutters where round-rod steel does not. He borrowed an idea from New York City subway vending machines: a protective bonnet around the padlock cylinder, making it harder to attack the lock’s weakest point directly. By the fall of 1971 he had produced fifty locks.
Michael Zane read about the invention and proposed a partnership. His family owned a Boston sheet-metal shop that normally made fluorescent lighting fixtures, which turned out to be exactly the kind of production capacity Kaplan needed. Zane drove a VW bus around the country, selling the locks to bike shops. A New York dealer decided to run an experiment: he chained a bicycle to a Greenwich Village signpost and left it there for thirty days. Sheldon Brown’s early Kryptonite history records the result: thieves stripped every removable part off the bicycle. The lock was still there. So was the frame. The story made national press. Zane, not a man to underplay a moment, wore a Superman costume to the Playboy offices in 1974 and came home with a product mention in the June issue. By 1987, Kryptonite was shipping more than 100,000 locks a year.
The lock’s design had one weakness, and someone found it in 1992. A journalist named John Stuart Clark published an article in a cycling magazine demonstrating that the tubular cylinder inside a Kryptonite U-lock could be defeated with a common ballpoint pen. A Usenet post that same year documented the same technique. Kryptonite did not recall anything. The information disappeared into print archives and niche discussion boards, where it sat, quietly, for twelve years.
In September 2004, a cyclist named Chris Brennan — whose own Kryptonite-protected bike had been stolen — learned the trick from a friend and posted it to a bike forum. Within days, someone had posted a video. A bike-store employee demonstrated the attack in five seconds for a New York Times reporter. The mechanism worked because a Bic pen barrel happened to match the inner diameter of the tubular cylinder closely enough to seat and turn it. Kryptonite’s anti-theft guarantee had been offering up to $3,500 per stolen bike. The company now faced the prospect of paying that sum for every stolen bike protected by one of their tubular-cylinder locks.
The replacement program covered hundreds of thousands of locks and cost the company an estimated ten million dollars. Kryptonite redesigned its line around disc-detainer mechanisms — the same family of technology Abloy had been refining since 1907 — and the tubular cylinder disappeared from their catalog.
Kaplan’s flat steel shackle was never the problem. The cylinder he’d borrowed from a vending machine, designed to be cheap rather than secure, is still installed in millions of padlocks and bike-share stations. It is still openable with a ballpoint pen. Kaplan even built a bonnet over it because he knew.
The internet didn’t invent the flaw. It just made 1992 feel like yesterday.
Sources
- Early History of the Kryptonite Bicycle Lock — Sheldon Brown — Stan Kaplan’s 1971 invention in Cambridgeport MA; Michael Zane’s partnership and VW bus marketing tour; the Greenwich Village signpost test; 1987 production figures.
- Kryptonite lock — Wikipedia — Company founding timeline, the 2004–2005 vulnerability and Bic pen exploit, the replacement program, and redesign to disc-detainer mechanisms.
- Bike Lock Fiasco — Center for Information Technology Policy, Princeton — Chris Brennan’s September 2004 forum post; the five-second demonstration for the New York Times; John Stuart Clark’s 1992 cycling-magazine article.