OnGuard Bulldog STD U-Lock with 4 ft Cable – 13 mm Hardened Steel Shackle (115 × 230 mm) – X2P Double Bolt Lock, Z-Cylinder Core, 5 Keys & Mount Bracket

This is one of those times that online doesn't really give you a good idea of the size and weight of the product. These locks are both bigger and heavier than I expected. Not that the description is not accurate it's just that I was surprised when I opened the package. The lock works fine, seems very well made and I will feel secure using it. If my bike gets stolen with this lock on it the thief will have to be very determined or professional. There is not much more I can do in either case.

This lock works great, and (so far) protects my bike even when locked up outside my building for hours all day or even overnight. My *only* complaint is that it tends to have a little rattle when biking and going over bumps, but that is pretty standard I think. I had trouble deciding between giving it 4 starts or 5, until I remembered how much better the mounting system for this lock is compared to other comparable locks. The mounting system for this lock is vastly more versatile, allowing my many different configurations that work on my different bikes (where as the mounting systems for other locks left me with no adequate options for a couple of my bikes, and I returned those to the store). I would definitely recommend this lock to others, and have now bought several to use on different bikes (at the same time).

I really like this lock. It feels really beefy and is big enough to get around my bike frame and the bike rack. Also, like the cable so I can loop through my wheel. When I first got the lock, it seemed to big to mount anywhere on my bike, so I was kind of bummed, but then I read the instructions, and saw that it could be mounted on the seat stem. I was skeptical at first, thinking it would interfere with my pedaling, but after I installed it, I didn't even notice it. So that's a plus! I've only had two issues. (1) Sometimes it's difficult to get the base locked onto the 'U'. I did lube the lock with white lithium lube so I know its not jamming as the key turns easily. So I'll live with it. (2) The lock clip that attached to the my bike came unscrewed when I was mountain biking. I know it was tightened when I installed, but I guess all the bouncing down the mountain caused the screw to back out and the lock to fall off. I have since reattached and put some loc-tite on the threads. Hopefully this will hold.

Superb lock. It’s very big kind of bulky, kinda heavy, but it will definitely make people think twice before trying to steal your bike using this.

Does it's job. Like the wide throat vs. the more narrow ones on the market. I own two of them and I think this is the one that comes with the nifty key with the built-in light. The only complaint. There is a plastic sleeve around the "U". It is not attached to the metal. Sometimes it will slide to one side and get low enough that the lock is difficult to lock up. Until I realized this was the problem, I got very frustrated with this. Last week, I got stuck in a bank of snow up in the mountains, no shovel and we used this, among other things, as a pick/shovel to dig us out. I'm sure OnGuard didn't intend that use, but just to let you know in a pinch this thing can do all sorts of stuff!

This is a good heavy duty lock that is easy to use. One high racks I clamp the bike frame directly to the rack without the cable. For low racks and longer durations I loop the cable through the rear wheel and clamp to the rack. It cones with an adapter for mounting the lock to the bike frame, but I have not used it because it's easier to fasten it to the carrier with bungee cords.

So far, this lock has done its job. I live in an area with moderate bike-crime and commute to an area with almost none. My garage is secure, but if I'm shopping near home, I want a big scary lock that'll make my bike seem significantly less attractive to a thief than the flimsy cable-locked bike next to me. This is that lock. At the end of the day, a bike thief with the right tools can break any lock and definitely any cable, unless you're willing to invest in and slug around professional grade steel chains. I'm not. I just want my bike to look less easy to steal and this lock does the trick. I have a strangely shaped bike, so it doesn't quite get around either of my tires and the frame, so I boot each tire to the frame with mini-u-locks, run the cable from this between them and onto this u, and secure this u to whatever I'm tying up to. There's an approximately 4" diameter water pipe at work that I lock to, and the round part of this lock fits around it no problem. The construction seems very secure and the insurance scheme, while a royal pain to fill out and send in, seems legitimate. My bike is my exclusive means of transportation, so I'm willing to make the investment to keep it secure!

OnGuard make good bike locks. Sturdy, well built and easy to use. Comes with perhaps too many keys (5!) but that's ok. Faster to use than the number-code variety. The 3rd OnGuard lock I have purchased in recent years. Good value for money.

Buenísimo. No me la roban nunca más

This is a great lock! It has survived for 1 year already with -30 °C winter temperatures without the holding bracket cracking or breaking, as some have complained about it. The lock is great, but the chain is very basic; it will be cut in no time, but at least it will work as a deterrent for a person trying to steal your wheel because the other one is secured to the frame with the U-lock.

Sturdy & strong with plenty of spare keys & handy light on one main key only. Comes with cable & carrier should you need it. A little on the heavy side, but that comes with the build quality.

Mi piace. E’ solido e ben fatto. La corda poteva essere più lunga ed è vero è pesante (io lo tengo nel bauletto)ma se si vuole un minimo di sicurezza…. Poi è fortuna si sà!