A bike lock is one of those things that everyday cyclists do not think of everyday -- until they come out of the quiki mart to realize some miscreant has ridden away on their bicycle. If they are lucky the thief is not a good rider and will crash and the bike will be recovered nearby, hopefully not too badly damaged, but many stolen bikes never find their way back to their owners.
To prevent this, companies that manufacture cycling gear have come up with all kinds of ways to lock your bike to unmovable object in hopes of deterring crooks, scoundrels, and all around bad dudes. That's just it, deterring, not preventing. If a person wants to steal your bike -- or your car, or your wallet -- bad enough, they are going to try. The thief might not steal the bike, but he can do a lot of damage to it in trying to. The solution is to lock the bike so if the thief happens to steal somebody's bike, it won't be yours. Cynical, yes, but realistic.
The most common type of lock seen is either a chain or cable or a u-lock. The u-lock is a curved piece of metal with a removable crossbar across the bottom, hence to name; looks like a "u". Various companies make them, in varying degrees of strength, weight, and styles and sizes. Two of most popular midsize or mini u-locks (though smaller ones can be had, usually used to lock chains although they can be used seperately) are the Onguard version of the U-lock, and the Kryptonite U-lock, which is arguably "the original" u-lock to see widespread use, mostly among commuters and messengers.
THE LOCKS:
Both designs are similar in overall layout; a u-shaped shackle, a long round, barrel base, and a keyhole covered by a rotating plate to keep dirt and grit out. Both locks have a rubberized covering over the shackles and the base and came with spare keys and a mount for carrying the lock clipped to the bike frame (something I would not recommend but which is often done).
THE KRYPTONITE is longer -- 9 inches long versus the Onguard lock's 8 inch length. Interior width of the shackles is the same at just under 3 1/2 inches so the locks are very similar in that respect. The Krypto is also lighter than the Onguard, part of which may be due to it's thinner barrel.
In addition to being lighter and longer, the Kryptonite has a plastic rather than metal keyhole cover. This means that when this part of the lock rubs on your bike it won't scratch the paint. It also has a different locking mechanism -- whereas the Onguard lock (and most other u-locks) have a shackle with straight ends, one end of the Kryptonite u-lock shackel is curved allowing it to pivot like the shackle on a conventional padlock, as well as come entirely off -- but this also makes competely removing and reinserting the shackle tricky, especially through a wheel or other part of the bike.
THE ONGUARD is a little shorter, which, since the best way to carry such a lock (the manufacturers frame mount notwithstanding) is inside a backpack of messenger bag, is nice. Since some riders for around town use throw it in one's back shorts pocket where it is easily accessible, this is even nicer. The shorter length makes carrying it in a back pocket or small backpack easier. However, it is also slightly heavier, so if you're riding with this in your shorts you better cinch up your belt!
The Onguard's primary advantage is the ease of use of it's locking mechanism, in that the shackle pulls straight out from the barrel or base of the lock. It's primary difference from the Kryptonite is that barrel locks to the u-shaped shackle on four points. Look below:
The insertion point for the shackle shows a mechanism for locking it on each side. The other insertion point is identical. The Onguard has each end of the shackle secured twice.
So which is a BETTER LOCK?
Unfortunately both are pretty similar. In the end, it comes down to details -- which feels smoother, lighter, which is easier to lock and unlock, which simply SEEMS right. I've never had a problem with an Onguard u-lock and I own several including this one, but I also have been using the Kryptonite on a daily basis as my regular lock, and at work in conjuction with a chain and padlock to secure the bike. Never had a problem with it, in rain, sun, grit -- it works fine.
