I'm cracking up over here! I guess it would have to at least be a Pinto, nobody would ever steal a Chevette or Yugo...
Until the lack of brakes causes you to get hit by a car, or crash into a pedestrian and cause severe injury.
A concealed spring-loaded shotgun hidden behind a door is, without any doubt whatsoever, intended to maim an unsuspecting person. A bicycle placed outside without breaks though? There are far too many plausible less than evil explanations for that to say with any certainty that a jury would side with the plaintiff. (Unless the shop did something particularly stupid like admit they put it there in that condition with intent to harm...)
Now, could the guy still sue? Yeah, of course. He could also sue if a perfectly normal bike that he stole gave him blisters. That would be pretty dumb, and he wouldn't win, but he could still do it. The only thing that really matters at the end of the day is "can you get away with it".
If there are better cases than the shotgun out there (and I imagine there should be if it is really so easy to sue for things like that), then I will of course re-evaluate my position.
This is the only case I could find on wikipedia. Placing a bicycle outside with no brakes hooked up is a far cry from rigging a spring loaded shotgun to the door of an unoccupied building.
It isn't even unheard of for people to legitimately (well, not legally I think...) ride bicycles without brakes, so where would you draw the line? If the police used a Ford Pinto as a bate car, could they be similarly at fault?