It's not every day that you see a major consumer brand on the defensive, but that's exactly what happened last week when the Kryptonite bike lock company, part of Ingersoll-Rand (NYSE:IR), was forced to respond to media coverage and widespread Internet chatter exposing a pretty remarkable (and embarrassing) security flaw in their well-known and well-regarded "U-locks."

Bike thieves are an adaptable bunch: If there's a lock, they'll figure out a way to pick it (or break it, or cut it, or simply walk off with the fence you had it chained to), but last week's revelations bordered on the comical. Some of Kryptonite's locks, it was discovered, can be picked in a matter of seconds using a common ball-point pen. (Video illustrating this is available online.)

It's a fairly stunning design flaw that's come as a shock to bike owners, retailers, and, no doubt, criminals. Sadly, it looks like it was also a shock to Kryptonite, which won't have details on how to collect replacement locks until Wednesday. (Check the company's website for more information.)

Bicycle locks are a relatively small part of Ingersoll-Rand's business -- the company is massive and reported $9.98 billion in 2003 revenues. Still, this news is a big blemish on a powerhouse brand. Given that, I'm somewhat surprised by the company's handling of this matter -- requiring customers to provide a registered key number, anti-theft protection registration, or a proof of purchase to claim an upgrade seems excessive.

I guess Kryptonite's motto says it all: It's a "Tough World" out there. However, it's not so tough on bike thieves, who are apparently just a flick of the Bic away from that shiny new Cannondale down the street.

Fool contributor Dave Marino-Nachison doesn't own shares of Ingersoll-Rand.