OnGuard Bulldog DT Review

Last Updated on January 12, 2024 7 Comments

OnGuard Bulldog DT

OnGuard Bulldog DT Summary

My score:

Check price:

Shackle thickness:

13 mm


3.17 lb (1.44 kg)

Size (internal):

4.5 x 9"

(11.5 x 23 cm)

OnGuard rating:


Other Security Ratings:

Sold Secure Silver

The OnGuard Bulldog is an great, mid security lock at a budget price. In this OnGuard Bulldog DT review I will look at how secure it is, how easy it is to carry around and use, the optional anti-theft protection, and possible alternatives.

How secure is the OnGuard Bulldog Standard?

Just like it’s main rival the Kryptonite Kryptolok Series 2, the Bulldog has a 13 mm hardened steel shackle that will resist cutting, prying, jacking and all but the biggest bolt cutters.

And the recently re-designed cylinder is bump proof and resistant to picking, pulling and drilling.

It also boasts a double locking mechanism that locks the shackle on both sides. This should mean that a thief needs to cut through the shackle twice to remove the lock. However, I have heard anecdotal evidence that this is not the case for this lock and if cut once, it can be pulled apart.

OnGuard gives the lock a 65/100 security rating which they classify as “high” (from a possible “basic”, “high” and “ultimate”).

Sold Secure, the independent lock testers from the UK give it a solid Silver rating (from a possible Bronze, Silver or Gold).

However, unfortunately ART the Dutch lock testers don’t seem to provide ratings for any OnGuard locks.

The Bulldog also comes with a 4 ft, 10 mm thick cable that offers very little practical protection.

Is the OnGuard Bulldog Standard easy to carry?

At 2.43 lb (1.10 kg) the Bulldog is one of the lightest 9 inch u-locks around and you can feel the difference in weight between it and the Kryptolok Series 2 (2.85 lb / 1.29 Kg).

You could probably carry it your bag without noticing it too much, but locks get wet and dirty and I think most people would prefer to use a frame mount.

OnGuard frame mount

OnGuard frame mount

The reviews for the mounting bracket that comes with the Bulldog are generally slightly more favourable than those for the Kryptolok Series 2 frame mount. They suggest it is easier to install and stronger. However, there are also many reports of it working loose over time.

But bear in mind there are alternative ways to carry any u-lock. There are a number of third party mounts and holsters available, or like me, you could thread it through the seat rails and secure it between the seat stay and seat tube.

Is the OnGuard Bulldog Standard easy to use?

The Bulldog is slightly wider than the Kryptolok Series 2, and this should give you a slightly wider choice of things to lock it round. However, it doesn’t have the “bent foot” shackle that makes the Series 2 so easy to fasten.

Because both ends of the shackle are straight, you need to fit them into the crossbar at the same time and hold the lock carefully as you turn the key. This is not a big issue though and in fact most u-locks work this way.

You get 5 keys with the Bulldog and one of them has a light to help you find the keyhole in the dark!

Just like Kryptonite, OnGuard also offer online key registration so you can get replacements should you loose your keys. However, unlike Kryptonite, the OnGuard key registration is for US customers only.

As with all u-locks, there are a fair few complaints about the locking mechanism jamming. This can happen for a number of reasons. But keeping the mechanism clean and regularly lubricated will reduce the possibility of it jamming.

However, the Bulldog does not come with a dust cover which could protect the mechanism from the dirt and weather that can start to stiffen the movement of the discs and cause these problems.

The Bulldog DT also comes with a 4 ft long, 10 mm thick cable to help secure your wheels or seat. These cables offer very little practical security for your bike. They are a nuisance to carry, a nuisance to thread through your bike and a thief can snip through them in seconds.

You shouldn’t depend on these cables to secure your bike, your wheels or your seat. Especially if you use quick release skewers.

In fact you can buy this lock without the cable and while it may only be slightly cheaper at least you wont feel compelled to use something that is essentially only a psychological protection.

Does the OnGuard Bulldog include insurance?

The Bulldog is eligible for coverage by OnGuard’s Anti-Theft Program. If you register with the program and your bike is stolen because your lock was broken, OnGuard will pay you the value of your bike up to a limit set by the security level of the particular lock.

In the case of this lock that limit is $1501. So if your locked bike is stolen, OnGuard will give you up to $1501? Well, maybe. In fact, OnGuard’s program imposes even more conditions on your claim than Kryptonite’s program...

First of all you need to register for this program within 15 days of purchasing the lock. And it’s not free. It’s $1 for 1 year, $10 for 2 years and $20 for 3 years. This is cheaper than Kryptonite’s cover but you can’t register online. Instead, you need to post a check, also including:

  • a copy of the receipt for the purchase of your lock AND
  • a copy of the receipt for your bike OR
  • a signed and dated valuation of your bike by an authorized dealer on that dealers stationery

You are not covered if:

  • your bike was not properly locked to a solidly anchored immovable post or object
  • the object to which your bike was locked was dismantled or cut
  • the frame of your bike was cut
  • the lock was not broken or opened by forceful means
  • torches, battery operated tools, or any power tools, including hydraulic tools, were used to open or cut the lock
  • you live in New York State
  • you live outside the USA

To make a claim you need to:

  • report the theft to the police within 72 hours
  • notify OnGuard of the theft within 7 days

When you notify OnGuard you need to do so by registered mail and include:

  • the broken lock as proof of its failure
  • at least one key
  • a copy of the police report
  • your Registration Form and attachments
  • evidence you have notified your insurance company, if you have insurance

Basically the OnGuard program is very similar to the Kryptonite program. However in the case of OnGuard, you will not be covered if your lock is broken by torches, battery operated tools or power tools which seems pretty restrictive!

What’s more, this type of anti-theft protection is not an adequate replacement for either homeowners/renters insurance of specialized bike insurance, both of which offer more extensive and reliable coverage!

OnGuard Bulldog DT Review Summary

With the OnGuard Bulldog DT [Amazon], you get a dependable, mid security lock at a fantastic price.

It is one of the lightest 9 inch u-locks about, making it very easy to carry. And it is also slightly wider than many of its competitors, giving you more options when locking your bike. The frame mount is reasonably good quality and generally dependable.

But the customer service you get from OnGuard is nothing like as good as from Kryptonite. They will not replace your lock if your keys get stuck and the conditions of their anti-theft protection are much stricter. You should also remember that this lock can be broken with the largest bolt cutters.

However, overall I think is a brilliant budget lock. The price is hard to argue with and it will defeat the vast majority of thieves. This is a great choice if you have a cheap bike or live in a low theft area.

OnGuard Bulldog DT U-lock and Cable

The OnGuard Bulldog is a great, mid-security lock at a budget price.

Product Brand: OnGuard

Editor's Rating:

If you have more desirable, expensive bike or live in a high theft area you might want to think of something a little more secure and unfortunately a little more expensive!

Alternatives to the OnGuard Bulldog DT

If the Bulldog DT is not quite what you’re looking for, then perhaps these alternatives will be more suitable…

Looking for something more secure?

OnGuard Pitbull STD with cable

The OnGuard Pitbull [Amazon] is the next model up from the Bulldog. At 14 mm, the shackle is 1 mm thicker than that of the Bulldog.

And it locks in 4 places. So while the Bulldog can be pulled apart with just one cut, the Pitbull would need to be cut twice to defeat it.

This extra protection is reflected in the security ratings, with Sold Secure classing it as Gold level protection. Of course it is heavier (50 g) and slightly more expensive. But not much so. And all OnGuard locks are such good value for money, I think it’s probably worth it.

So if you’re looking for a lock that’s the same size as the Bulldog but that offers a much higher level of protection at a fantastic price, this is a great choice.

Looking for better customer service?

Kryptonite Kryptolok Series 2

The Kryptolok Series 2 from Kryptonite also has a 13 mm shackle and a Sold Secure Silver security rating.

But the build quality is also a little better and the after sales customer service is second to none.

Check out my full review of the Kryptolok Series 2. You can also compare the specs to loads of other u-locks.

OnGuard Bulldog DT Specs

OnGuard Bulldog DT

OnGuard Bulldog DT Summary

My score:

Check price:

Shackle thickness:

13 mm


3.17 lb (1.44 kg)

Size (internal):

4.5 x 9"

(11.5 x 23 cm)

OnGuard rating:


Other Security Ratings:

Sold Secure Silver

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About the author 

Carl Ellis

I've had bikes stolen in London, New York and Barcelona. Yep, I was a serial, international, bike theft victim. In 2015 I decided to stop the rot. And not a single bike's been stolen since! Brakes, yes. Bells, yes. But they're another story. Everything I learn, I document on this website. More about my story. Contact me. LinkedIn.

  • Bought the on guard lock and am very dissatisfied with it. The mounting bracket does not hold the lock and it is impossible to use. I am very unsatisfied with this lock would bot buy again or recommend this lock to anyone.

    • I have this lock and although the lock has a slightly crude feel to the mouldings 2 years of daily use later the lock still works, the bracket has survived bumping up and down pavements and most importantly I still have my bike.

  • Bought this as I wanted the extra width. Fastened it easily would n first use. Have not used the frame mount yet. No point in signing up for insurance since I live in the uk.

  • I’ve owned this lock form over 5 years now. I bought it to replace my Kryptolok Series 2 U Lock that jammed. Fortunately a kind gentleman at a nearby Home Depot used a 32″ bolt cutter to cut my Kryptolok Series 2 with easy. Unlike the Kryptolok Series 2, the OnGuard Bulldog can’t be cropped with he medium size bolt cutters that most bike thieves use.

    Any lock can jam, and I don’t hold that against Kryptonite, but the steal used in the shackle of the Kryptolok Series 2 is softer and easier to cut. The Kryptonite Evolution is a much better option then the Kryptolok Series 2, it’s shackle is far more cut resistant. But for a 13mm shackle, this Bulldog is my choice. I use mine to as a secondary U Lock in conjunction with my Kryptonite Evolution Series 4 U Lock or OnGuard Brute.

    • Hi George,

      I’m not convinced that the Bulldog is any more secure than the Series 2 to be honest. But the combination of the Evolution Series 4 and the Bulldog as a secondary lock is a good one!


      • I’ve personally cropped the Kryptolok Series 2 lock of my bike with 30″ bolt cutters from Home Depot with relative ease in less then one minute. About 3 months later, I was unable to cut the daughter’s Bulldog from her bike on campus after she lost her key and had no idea where her other 4 keys were! My friend had to help, using his angle grinder to cut it off. I was shocked my Kryptolok Series 2 cut so easily. The Evolution Series 4 FAR superior to Kryptolok Series 2 at holding off any bolt cutters.

        • Yes I’d agree that the Evolution series is far superior to the Kryptolok but I’m really surprised you found the Bulldog with stood bolt croppers better than the Kryptolok!

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