The OnGuard Bulldog DT is a decent U-lock for a lower price than most options from reputable lock companies. The U-Lock is a bit larger than most, making it more likely to accommodate your bike's front wheel (removed from the front fork), back wheel, the bike frame, and the bike rack. It also comes with a mount so that you can attach the lock to your bike frame, but we didn't like it very much. The robust mount and the lock's design make it a solid medium-security U-lock. According to its manufacturer, it has a double-locked shackle design, requiring bike thieves to make two cuts on the U-lock and not just one, which adds to its security. Interestingly, we could defeat it with one cut through the shackle with an angle grinder. It lacks the protection that other U-Locks in our bike lock review provide, and depending on your biking equipment and wheels, we think you should pass on this if you need higher security.Editor's Note: We updated this gear review on January 25, 2022, to include additional information on whether this product is worthy of purchasing and other options to consider.
OnGuard Bulldog DT Review
Cons: Lacks the security of better U-locks, clunky design, mount is not our favorite
Compare to Similar Products
OnGuard Bulldog DT
$43.12 at Amazon
$51.25 at Amazon
|$53.19 at REI|
Compare at 4 sellers
|$14.99 at Amazon|
Compare at 2 sellers
|Check Price at REI|
Compare at 3 sellers
|Pros||Inexpensive U-lock, durable, good quality||Secure, includes 5 keys, price is nice||Inexpensive, more secure than many in its price range, high quality||Lightweight, easy-to-carry, easy-to-use||Lightweight, flexible, easy to use|
|Cons||Lacks the security of better U-locks, clunky design, mount is not our favorite||Clunky mounting hardware, heavy||Locking mechanism stuck a few times, lackluster frame mount||Minimal security, can be compromised with the right tools quickly||Too small, minimal security|
|Bottom Line||The Bulldog DT is large and accommodating, but if you need a U-lock for higher security needs, this one might not be the best option||This lock provides great security and versatility at an affordable price, and while not our absolute favorite, it's pretty close||This inexpensive U-lock offers versatility and security that is likely to fit the needs and budgets of many cyclists and commuters||If you're in the market for a highly portable and lightweight lock but without much security, this one has your name on it||Great for preventing the "snatch and grab" while you make a pit stop but does little to prevent a real bike thief from swiping your ride|
|Rating Categories||OnGuard Bulldog DT||OnGuard Brute STD||Kryptonite Kryptolo...||ABUS Chain Lock 120...||Hiplok Z Lok|
|Ease of Transport (25%)|
|Ease of Use (20%)|
|Specs||OnGuard Bulldog DT||OnGuard Brute STD||Kryptonite Kryptolo...||ABUS Chain Lock 120...||Hiplok Z Lok|
|Measured weight (lbs)||3.0 lbs||3.6 lbs||3.2 lbs||0.5 lbs||0.1 lbs|
|Type of lock||U-Lock + cable||U-Lock||U-Lock + cable||Chain||Reusable zip tie|
|Primary materials/thickness||13mm steel; braided steel cable||16.8mm hardened steel||12.7mm hardened steel; braided steel cable||4mm hardened steel||Steel core security tie|
|Locking dimension||U-lock: 6" x 11"; Cable: 4'||7.5" x 10.5"||U-lock: 4" x 9"; Cable: 4'||43" circumference||16.5" circumference|
|# of keys included||5 keys||5 keys||2 keys||N/A||1 key|
|Tin snips||No||No||No||Yes, requires two cuts to defeat||Yes|
|Hacksaw||Yes, eventually||No||No||No||Yes, quick|
|Bolt cutters, 36"||No||No||No||Yes, but not very easily. Requires two cuts||Yes|
|Number of cuts to free lock||1 cut||2 cuts||2 cuts||2 cuts||1 cut|
Our Analysis and Test Results
We didn't find much to get excited about in terms of security. Granted, it's a less expensive U-lock, but OnGuard gives the Bulldog DT a "70" or "high security" rating according to its internal rating system. We could agree if they are referring only to the U part of the lock. However, our testers discovered that the shackle is this lock's vulnerable spot.
The Bulldog is burly for thieves with hand tools: there's no getting through this lock with hammers, tin snips, wire cutters, or bolt cutters. Once you introduce power tools into the equation, it's over, as with all locks. What downgrades the score of this lock is how quickly we were able to cut through this lock compared to other thicker U-locks we tested. This bike lock quickly succumbed to an electric-powered angle grinder within mere seconds. The worse news? If thieves can cut through the shackle, which we accomplished much easier than expected, that disables the metal plate that locks the U into the shackle. So, in one cut, thieves can nab your bike and gear. Therefore, we generally recommend U-locks that require two cuts to the U portion, or at least a shackle that's more difficult to cut through.
Ease of Transport
If you're not necessarily "handy," installing a bike mount could be something of an adventure. Perhaps having this in mind, the designers at OnGuard created a bike mount that is simultaneously robust and easy to install, even if you're not all that skilled at that sort of thing. The low-profile mount fits on most frames and keeps the lock in place, even on some rough roads. The mount is sturdy. However, many of our testers didn't love that it positions the 3-pound lock off-center on the bike. We prefer lock mounts that keep the lock streamlined with the bike frame. If you're toting the included cable around for additional security, it will need to be carried in a pack.
While the OnGuard Bulldog DT isn't the heaviest U-Lock in our lineup, we bet you'll notice the extra three pounds of weight on climbs no matter if the lock is mounted to your frame or is stuffed into your backpack. That's just part of being a U-lock, and actually, this one is lighter than several models. It's also a larger lock, so if you ride a smaller frame (read: 50cm or smaller), you might not be able to mount this lock directly to your frame. Larger sizes mean they can fit around more objects but also more of a bear to transport.
Ease of Use
Our testers complimented the OnGuard Bulldog for how easy it was to use. There was no fighting or odd "grippiness" to this lock. Every time we used it, it came apart and locked up smoothly.
We also appreciated that this lock comes with five keys — one of which has a light on it. If you're a busy bike commuter, it stands to reason that you might misplace a key. Having four extras is excellent insurance that you won't run out of them too quickly.
What is not easy to use is OnGuard's protection policy which claims that it will reimburse you up to $1501 if your bike is stolen using their lock. What they put in the fine print is that you have to register your lock and pay to register it in order to qualify. And, if you happen to have your bike stolen and you want to collect on this policy, you must provide them with receipts for the lock, the bike, an evaluation of the value of the bike, and then proof that the lock failed (most often: the broken lock itself). As you can imagine, this isn't an easy thing to do. Because of this, we didn't add any extra points to this metric because we assume most riders will not be able to collect on this policy. Most theft insurance policies follow this scheme (OnGuard is not the only company to flash big dollar signs and then have rigid stipulations). For this reason, we don't put much weight behind these theft protection policies.
Our testers were impressed with this U-Lock that enabled us to secure our commute bikes to nearly any bike rack and use the most secure method: locking the front and back tires next to the frame with the bike rack. There were only a handful of situations where we encountered a bike rack or on the trailhead where due to the constraints of simply being a U-Lock, we couldn't lock our bike securely. But, in conventional urban settings, this lock is adeptly versatile.
The U-Lock includes a 4-foot cable, which could make this lock a bit more versatile if you live and commute in a low-risk area. However, we recommend locking both tires to the frame and bike rack. If you seek a lock for medium-risk areas, the cable isn't going to do much than deter a snatch-and-grab opportunist. Note: you cannot use the cable on its own, and once the U-lock is defeated, the cable is also defeated.
Should You Buy the OnGuard Bulldog DT?
The OnGuard Bulldog DT is ok, but its clunky design, off-center mount, and lower security (as far as U-locks are concerned) didn't entirely impress us. Since there are better options, we recommend that our biking friends spend a bit more money to get a better bike lock.
What Other Bike Locks Should You Consider?
There are plenty of other bike locks in the review that don't cost a whole lot more, but that will offer you more security and peace of mind, such as the OnGuard Brute STD. This option is wallet-friendly and offers more security.
— Rebecca Eckland
Ad-free. Influence-free. Powered by Testing.
GearLab is founded on the principle of honest, objective, reviews. Our experts test thousands of products each year using thoughtful test plans that bring out key performance differences between competing products. And, to assure complete independence, we buy all the products we test ourselves. No cherry-picked units sent by manufacturers. No sponsored content. No ads. Just real, honest, side-by-side testing and comparison.Learn More