I managed to find two of the number by stretching it moderately - I rotated it one number at a time, hitting --39, when suddenly it moved a tiny bit and the 3 and 9 refused to budge. Then I pulled harder and rotated the first two numbers. Around 20-something, it popped open. Ideally, a good lock won't reveal this weakness - I should had to try all 1,0000 combinations.
Total time spent: less than 4 minutes. It was a Schwinn coil bike lock, by the way. Nothing against Schwinn - my last bike was a Schwinn and I was rather fond of it. But it had a lock like this, and both bike and lock got stolen, along with other stuff on the bike. So... now I understand how I might have locked it, and then it ran off.
So... using these locks to secure your bike = probably not the best of ideas. I mean, the method I used involved pulling pretty hard on the lock by putting my legs through the coil and stretching it, so both my hands could turn the numbers.