Kryptonite Keeper Long Shackle 12mm U-Lock Bicycle Lock with FlexFrame-U Bracket

I had a long Kryptonite bike lock but lost one of the set of keys and was not happy with having one key for a lock for my bike. So I ordered this off Amazon because I could not find an affordable long U-lock in my local bike shops, and there are several in the area. I was surprised that I could keep the old U part of the lock and use it with the new locking part. Why would I do such a thing? I had a little trouble getting the plastic part on the new U off and did not want it as I was not going to attach it to my bike. I'm in a city with a lot of bike thefts and so I have a crappy looking bike and three (sometimes 4) locks, I'm not attaching them all to my bike. Ugly bike+3 bike locks*leaving bike outside=Not getting stolen in 10 years. I love the long U lock because I can get it around a parking meter base, the bike frame and sometimes the front wheel. The regular bike locks are too short to get them around whatever I'm attaching the bike to (iron fence, skinny pole, railing, etc) and my frame.

This is the third Kryptonite lock I buy and the first Keeper. The lock works perfectly. I have never had any problems with Kryptonite lock in general, and this was not the exception. The lock itself is not as heavy as other, "more secure" locks from Kryptonite, but it seems just as sturdy. I feel safe leaving my bike in a park-and-ride for the whole day. They changed the bracket and it's much easier and straightforward to attach it to the bike, but it has the same problems that that other one had. Mainly, it gets slightly loose over time, not enough to stop being functional, but enough to make it sound like all the screws in the bike are about to fall off. It is a matter of tightening it every so often, or just carry the lock in your backpack like most people do. Not a deal breaker though. Overall, the lock is five stars (the bracket not so, but compared to other brackets out there, it is on par).

The lock is very clumsy and the key to the lock is difficult to work.

I own an Austro-Daimler road bike. Most of the times I find an empty bike rack somewhere to lock it up, but sometimes I would have to lock it to poles and such. The 11.5" length is just the right size to do just that. It's not too big to be clumsy, and not too small that it fails its purpose. The length has a big advantage, you can easily lock up the front tire, the bike frame and the bike rack together. The design is quite sturdy, you can be completely confident of the security of the bike even if you're in a not-so-favorite area of your city. I only have one issue with this product, and it's the lock bracket that comes with the lock. The lock bracket fits well enough on my bike's frame-rod when I put extra padding between the bracket and the frame (the padding ships with the bracket), and tighten the screws real well. Though, after a while (say a week or so), the bracket starts getting loose and the lock starts coming in between my legs while I'm biking. Admittedly, some roads I ride on are really bumpy and I rack my bike up on the bus a lot, so the vibration may make it loose, too. Nonetheless, I'd like to see them come up with a more flexible and tighter design for the bracket. All in all, a recommended buy for your bike.

Fantastic Product and Customer service ! I have used them since college, many years ago. This model is security 6, thicker than the older one I had. The bike mount is very well designed too allow esay removal. I placed mine so I can slide it ouyt immediately as defense against muggers, (been mugged twice :( ) The company unlike most is very responsive to customers, it provides with free spare keys, and in my case sent me a spare mount for my mugged bike, where I kept the lock so I could use the lock im my replacement bike. My kind of guys !! Thanks.

Kryptonite locks are the best out on the market. I still have a Kryptonite lock from over 30 years ago. Never lost a bike yet that was locked with a Kryptonite. Yes, nothing is invincible, but this is a Huge deterrent. Easy to use, great bracket to attach to bike. These locks will last for years. I purchased this lock for a mountain Bike as it is longer which works well for the larger frame and tires of a Mountain Bike. I also use Kryptonite for my Road Bikes. Good Seller, Great Price. Quick shipping and delivery. I would recommend Seller and Product

Nice length to lock front wheel to frame without removing wheel! I have the hydraulic disc. If the front wheel is off, and you accidentally pull the brake lever, your S.O.L. and will need to carry bike to bike store for service on brake that wont retract. With this lock there is no need to remove front tire and rick the Disk Brake problem. UPDATE: 7/10/17 Lock will not open! I rode my bike all the way into town for an important appointment but lock would not open. I fought it for 30 friggin minutes! I missed my appointment. This thing really bites a donkey. What's up Kryptonite? I thought you guys were better than this....

The lock itself is great, but if you want to be able to attach it to your bike frame for storage, pick a different one. It comes with a piece that you can screw onto the frame of your bike, and the lock slides onto that piece so that you don't have to worry about carrying a big lock around. One problem with this piece is that it absolutely will not fit on a large-framed bike like a mountain bike, even with extra-long screws. The other problem is that the piece attaches to the side of the lock instead of the base, so the length of the lock must run parallel to the part of the bike frame it is attached to. Therefore, the only part of most bike frames that will be long enough to accommodate this lock is the top bar between the seat and handle bars. But to keep all of that clear of the brake and gear lines that run along the frame in that place, you have to install the lock-keeper sideways, so the lock is in the way of your legs while you ride. Basically, unless you have a bike with an extremely large but thin frame, you won't be able to use the lock-keeper to store your lock.

This lock is top notch for locking my bike. Very good price for the money.

It’s a good one for security

Very useful and sturdy

Good quality and secure feeling