Knowing HOW to use a lock is as important as the brand of lock. About 90% of the bikes I see locked up in my neighborhood are NOT locked correctly. A U-lock needs to be attached to the rear wheel, just behind the seat tube.That lock needs to be attached to a sturdy steel pole set in concrete, not a flimsy bike rack, held together with two bolts. A second lock (which can be a "heavy duty" cable lock) secures the front wheel to the frame. Lock the bike where a crook is gonna be seen. I lock up next to the ticket booth at the movie theatre, not in the alley behind the theatre.
The best "cheap" lock is the OnGuard Bulldog U-lock. About thirty bucks. The "mini" version works well for road bikes and hybrids. The best expensive lock is the Kryptonite New York 3000 U-lock, for around seventy bucks. An eight pound Kryptonite chain is as strong as the four pound New York 3000. But, who wants to lug around an eight pound chain?
A U-lock needs to be attached to the rear wheel, just behind the seat tube.That lock needs to be attached to a sturdy steel pole set in concrete, not a flimsy bike rack, held together with two bolts.
I'm having trouble grokking this. If its just attached to the rear wheel, couldn't a thief cut the wheel? Or unbolt it (especially with the quick detach tires)? He couldn't ride it away, of course, but he'd only need to replace the tire to have a resaleable machine. Or do they just not do this?
Most of the "official" bike racks in my local neighborhood have all the metal low down -- you almost have to use a chain or cable.
The worst bike rack design I've seen is that of a nearly brand new library nearby that had a "big name" architect. I guess that architect hasn't been on a bike since he was 5. The "rack" consisted of a series of grooves in the ground into which apparently you are supposed to set either a front or rear wheel. On an adult bike this is not sufficient to hold the bike up. The groove collects rain water and debris. Next to the groove is a ring embedded in the cement. The ring is too small for even the end of a modest cable lock. I have to carry a spare lock to create a hole for the cable. Now that I think about it, I think I'm just going to use sign posts from now on.