Kryptonite Keeper 12 Standard Heavy Duty Bicycle U-Lock with Bracket (4-Inch x 8-Inch), Black

If you care enough to buy a lock for your bike in the first place, then you should care enough to get a lock that works better and easier than another lock, on top of giving you great security, so you will get into a habit of employing it all the time and not be lazy because the lock takes more effort to use. Lazy? Yes, and laziness is the biggest reason to not use a lock you bought to protect your bike. Just having a strong U-lock isn't good enough. You have to use it. An unused lock is the worst security feature a lock can have. Easier, with top security features is just better. You'll use this Kryptonite lock and that will save your bike more times than you will ever know. I put it in the same realm as building a better mouse trap. Having returned an On-Guard 5510 Mini U-Lock with Additional Security Cable (4 feet) to Wal-Mart where I had bought that lock, I chose this Kryptonite lock instead because, although On-Guard claims to be "obsessed" about security they sure aren't when it comes to product design. Bottom line is if you have a lock that is not as easy for you to use, then you will of course use it less and take a bigger risk with your bike becoming a crime statistic (stolen). Amazon had Wal-Mart beat on price for this Kryptonite lock, too. Comparing Amazon's service to Wal-Mart's wouldn't really help, since Wal-Mart forgot what service is years ago, and Amazon has consistently provided me with better service in all areas for many years now. Shipping for this lock, along with Avenir Tightrope Cables (12mm / 7 feet) - to make securing my bike a more complete security system for my wheels and saddle along with making more work for a would-be thief - and a Bell Dawn Patrol LED Headlight took just 4 days using Super Saver shipping, and you can't beat that. My Planet Bike Blinky "3" 3-Led Rear Bicycle Light , that I purchased at the same time, was packaged and sent along separately, but still arrived on the same day. Look for those reviews from me, too, should you like this one. This U-lock is very tough and I don't think you could easily find something that would cut through it, at least not something you could easily carry with you and go unnoticed. Seems more like someone would have to use a diamond wheeled grinder type of cutter with a power drill, at the very least, and that sure wouldn't be discrete or fail to draw attention. So while someone would not be able to easily steal your bike with this lock - if properly secured - for errands, short trips to a store, or in a busier type of place where you could even leave your bike all day, it won't be for you if you leave your bike in high-crime areas. I wouldn't trust this lock to be the only means of securing your bike at night for a long period of time or in an area with few people around and little activity during the day, as people being around and seeing your bike is one step in your security plan to make stealing your bike a less attractive option for a thief. One thing I really like about this Kryptonite lock over the On-Guard U-lock is that while On-Guard uses a dual, straight bayonet system on both sides of the locking arm to attach to the shackle, this Kryptonite U-Lock has an easier and better system to attach the locking arm onto the shackle. It's not dual, straight bayonet on both sides. One side of the locking arm of this Kryptonite lock has a short, angled part of the locking arm that helps you to guide and fit the locking arm into the shackle for that side, then you just swing the locking arm around the frame of your bike and a stationary object and clasp the other side of the locking arm (which has a straight bayonet fitting) into the other side of the shackle, then lock it by turning the key. To me, Kryptonite's is just a better design that makes attaching the locking arm to the shackle a little easier in warm, dry conditions and especially easier in cold, wet conditions. It also makes it easier to attach the locking arm to the shackle by obtaining a little leverage, if needed, for those times when you have to use a stationary object (like a pole) that is larger in diameter than some others when you lock up your bike. The dual, straight bayonet system for the locking arm with On-Guard's lock makes you press down and use compression alone (your muscle strength) for attaching the locking arm to the shackle. Kryptonite's design, with one side of the actual locking piece of the arm at an angle, lets you lock that side in and pull as well as push down on the locking arm if you need to. As luck would have it, since I have received this lock the weather has taken a turn from nice and warm to colder than a mother-in-law's kiss, with ongoing cold rain or drizzle and I have really found out just how much better Kryptonite's design and locking system works, which means it just makes it that much easier to lock up my bike. Locking up my bike properly is a habit I don't want to break. If a lock is more of a pain in the butt for me to use, like the dual, straight bayonet system On-Guard uses in their U-lock design, then I'm less likely to use it all the time, which means a thief will be more likely to take my bike. And that would make me sad. In short, you spent your good money on your bicycle purchase. Spend a little more and get a good U-lock like this one, or a stronger one if your area is more of a high-crime/high risk area, and use it along with a good cable like the Avenir Tightrope Cables (12mm / 7 feet) . Little out-of-pocket cash, but you will have a security system that will intimidate most thieves, so the opportunists will give up without even trying and the more determined thief will move on to an easier target. For those interested in Kryptonite's Anti-Theft Protection offer, yes, you can register the lock and your bike with Kryptonite. You must verify your bike's serial number and purchase price with Kryptonite plus pay a yearly fee, along with other requirements and restrictions. It is all detailed in the enclosed package with the lock, and is available on Kryptonite's website if you want to know more.

I guess they finally fixed the clamp problem, because I was able to use it the intended way. I only use the clamp when I don't have my backpack on me, so I can't speak for longevity. It does seem to be sturdy, though. The barrel turns freely when I operate the lock, given that you've inserted the key properly. No issues there. My model looks slightly different than the one pictured, and came with longer oval keys that have a solid feel to them. The lock itself is relatively heavy but that's to be expected. MUCH better than the Wally World locks. I feel confident leaving my bike alone with this lock, however, I do live in an area where bikes are not stolen that often, and I also never leave my bike for periods longer than 2-3 hours. You may want a stronger one if you live in a bigger city or leave your bike outside. ALWAYS ALWAYS ALWAYS pair a U-lock with a chain or wire lock with a separate padlock when leaving your bike for extended periods of time. I cannot begin to describe the way people at my university lock their bikes up. Despite having decent locks, they somehow manage to make it scream "PLEASE STEAL ME". Please don't be careless; you're the only one that will get burned from it. This lock is definitely worth the price. Very satisfied!

I've had this lock for almost a year now. First thing, all of the reviews complaining about the clamp being on the wrong side are just foolish. The clamp can easily be changed around via a simple bolt, and it can be made to fit any need. I've had the lock clamped to my bike the entire time and it works great and doesn't slide around or fall off. You'll also read a lot of reviews about this thing being broken. The thing is nowadays there are mini tools that can cut through just about anything, and quickly. I view this thing as more of a deterrent than a 100% full proof lock. Therefore I've used this lock combined with a thick chain lock to keep my bike secured in downtown Fort Lauderdale, and at the beach. It's always been kept outside. To put that in perspective, when I moved to the beach 4 out of 5 bikes were stolen from my building in less than 2 months... mine was the only one that wasn't. To be fair, I noticed most of the bikes had minimal security, such as small basic cable locks only, which were quickly cut (most of them were taken during the day!). Another thing is that where possible, you'll want to keep the keyhole pointed downward. I had his thing in the rain for so long with no issues, but one time the keyhole was pointed up and a heavy rain came through, and it was full of rust and pouring out just the same. Nevertheless, it's still held up and still does. But since the rain I've had the occasional complication with the lock mechanism. All in all, for the price, this is a great lock in my mind.

EDIT: Two days after I wrote the 2 star review below, my bike was ALMOST stolen. The lock showed evidence of being cut with a saw in three separate locations but the perpetrator obviously gave up before getting all the way through. Despite any inconvenience with the lock sticking, I'm very grateful I had this lock on my bike. I just ordered the same lock again as a replacement. Original review: After about of month of multi-daily use, the locking mechanism gets stuck about 50% of the time. It opens after jiggling the key a few times, but is inconsistent.

do NOT buy this lock! Today I had a very early morning and it was raining. I unlocked my bike without a problem and rode to work. Upon arrival I tried to open the lock again in order to safely lock my bike. After about ten minutes of trying to turn the key to open the lock, with extreme frustration while standing in the rain, I smashed the side of the lock on the pavement (there is now a dent) and the lock could now be opened using the key! All it took was a smash on concrete. Obviously this isn't a sustainable solution, I can't be smashing your lock every time it needs to be opened. I tried to return this piece of junk but the website is so bad that you can't submit a customer service request. I tried two different browsers, still nothing. Also the "attachment" button fails every time I try to add the receipt (even in different file formats). Googling I couldn't find the email address or a phone number to contact. Well great. I posted on their twitter page, no response yet. Eventually I found a website (Zendesk ?) that allowed me to submit my warantee request.... still waiting on a response. I don't expect I'm going to get a refund anyways because I hit the lock out of frustration. But at the very least, please don't put yourself through what I did. Don't buy this piece of garbage. I'd suggest not buying kryptonite either since they clearly do not make it easy to return a defective product.

For less than $20 this U-lock does its job. It isn't the most sturdy lock out there, if you plan to leave your bike outside for long period of time, especially in cities where bike theft is high such as SF or NY; then this isn't the lock for you (you'll probably want to get more expensive lock or at least get a locking cable). For short periods of time and in places like the park or college campus, this lock works fine. It is also a flat lock type so it is better than most cylinder locks. The bracket for me didn't work where it was intended because my frame was too big on the top, however like in one of the pictures, I put the bracket on the side and it works wonders.

In my city U-locks are still relatively rare. Most people will lock their bikes with cheap and flimsy cable locks. This basic U-lock will keep your bike reasonabily safe in a big city. Although ANY lock can be cut through, I believe you should not risk to buy a cheaper lock than a Kryptonite (right now this one is CHEAP, probably because the company is replacing this model with the newer ones). I commute 30 Km everyday between school, work, supermarket, cinema, etc., and so far my bike has survived. I often lock it outside metro stations, or around busy plazas for several hours. Selecting the place to lock your bike DOES make a difference. I attached the bracket to my frame. The lock rattles with bumps and cobblestoned streets. It's annoying at first, but It's better than carrying a backpack just for the lock. The only serious issue with this lock is that rust becomes a problem after a few months. I know locks are not made to be permanently immersed in water, but they are meant to be used outdoors. Mexico City is very rainy during Summer months (downpours occur every afternoon) and sometimes the lock can be stuck because of the rust generated after rain. A little oil does the trick, though.

I just received my Kryptonite Keeper 12 U-lock w/ mounting bracket. I read the other reviews and was worried that the mounting bracket was going to prove to be a problem. I needn’t have worried. Because of the lock’s design, it CANNOT be mounted INSIDE the triangle created by the frame tubes and must be mounted so the lock, when stored in the bracket, is NEXT-TO the frame. Here is the procedure I used to install the mounting bracket: 1) Loosen the screw on the piece of the mounting bracket that is secured to the “U” portion of the lock. 2) Select a point on the bike’s frame tube where you would like the lock to be stored. 3) Press the red button and remove the lock from the mounting bracket. 4) Place the supplied pad under the mounting bracket and install the screws. Do not fully tighten them. 5) Slide the lock into the mounting bracket and make any fine adjustments. 6) Tighten all hardware. 7) Ride the bike up the bike trail to the House of Beer (Dunedin, FL) to test the instillation.

Fácil de usar y bien sólido. Incluye un sistema de soporte para llevarlo en el cuadro de la bici que es bastante cómodo.

Le produit et un bonne antivol d'appoint pour les arrêts minutes il permet de sécuriser la roue arrière en passant dans les hauban. Ce U est un bon dispositif il coûte aussi cher qu'un câble pour une sécurité accrue grâce entre autre à sa serrure à disque il est également très intéressant de part son système de fixation au cadre qui fonctionne très bien ( petite astuce si comme moi vous avez un vtt mettez le support derrière le tub de selle ;)) Enfin bref bon antivol pour les arrêts minutes mais pas plus car pas assez sécurisée.

Looks solid, accepts by insurance companies and i still own my bicycle

Cannot be broken. Need not saying anything else.

Ottimo prodotto. Lo consiglio a chi vuole un lucchetto abbastanza affidabile e robusto. Ne avevo preso uno uguale a questo, diversi anni fa, e ancora lo uso. Funziona benissimo, anche se ogni tanto l'ho dovuto lubrificare perché si chiudesse con più facilità. Molto comodo il sistema di fissaggio che ti permette di tenerlo fermo sopra il meccanismo centrale e non nel cestino dove farebbe anche rumore e ruberebbe spazio. Nel complesso soddisfatto anche considerando il rapporto qualità prezzo.