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Review: OnGuard Bulldog Mini TC Bike Lock

When my bike was stolen a few months ago, the bandits also made off with the lock. So, along with picking up a new ride, I had to look into a new locking system. As with most of my gear decisions, I wanted something light and easy to pack and carry.

The lightest and most compact locks out there are the cable locks. However, these locks are often compromised with a simple pair of bolt cutters and a quick snip.¬† So I had to consider something beefier, and decided to look at U-Locks. A U-Lock (sometimes called a D-Lock) consists of a steel bar shaped like a “U” with a straight bar locking mechanism. It is heavier than a cable system, but is much more secure. To compromise a well constructed U-Lock you would¬†really have to put some elbow grease into it, and would typically need tools like a hacksaw or pry bar.

Not willing to completely wave the white flag on a lightweight solution, I set out to find the smallest and lightest U-Lock I could. At 1 pound, 11 ounces, the OnGuard Mini fit the bill.

Great Strength to Weight Ratio

The Mini is at least a pound, and in some case 3 or 4 pounds, lighter than the other locks I looked at. Yet it does not compromise security. The “U” is made of 1/2 inch hardened steel and the locking mechanism uses a drill and pick resistant double bolt system.

Some people feel that the small overall size of the Mini might actually make it more secure. The thinking is that the limited room makes it harder to get good leverage with a pry bar type tool… which in turn makes it tougher to open with brute force. In addition, at least for me, the weight savings of this lock means I am more likely to carry and use it. Heck, I also find that because it is so light I even bring a secondary cable just so I can secure my front tire to it.

Almost Too Small

It certainly isn’t as convenient as a rolled up cable would be, but the Mini is small enough that I can fit it into my backpack alongside a laptop and rain gear – with room to spare. It is also compact enough that if you want to mount it to the frame of your bike, you have several options for doing so. This is unlike the larger U-Locks I looked at, where you would be pretty limited in how you attached it to your bike.

If there is one problem with the Mini, it is that it is almost too small. The depth of the lock limits what you can actually get the lock around. It is a perfect fit for common items like bike racks, street signs, parking meters, etc. But I’ve run into a couple of situations where I was just unable to get the Mini around the object, and then also around the frame of my bike in order to lock it up. In one case I was trying to lock my bike to a fence pole, in another it was a small tree. Both of those were uncommon situations, but it does drive home the point that you are limited in what you can secure your bike to.

Best Solution for a Lame Problem

In the end, it sucks that you even have to waste energy and money on something like a quality bike lock. But there is no sense beating your head against reality. There are losers out there who steal bikes – especially in the Boston area it seems – and unless you plan on riding around on $15 Craigslist specials, you better secure yours. The OnGuard Bulldog Mini isn’t a perfect solution to this problem, but if you are looking for a system that balances weight and security, it is the best I have found.


The smallest, lightest U-Lock I was able to find provides excellent security at a very reasonable price.


Secure. Lightweight. Easily packed and carried. Rubber coating protects your bike from scratches. Includes a key with LED light.


Small size limits the objects you can secure your bike to. Included mounting bracket is weak, you will most likely need a better solution if you plan on mounting this lock to your bike frame.

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1 Comment

  1. Kristin

    Good review. Just bought a used Trek 3700 off of Craigslist to start my new life as a mountain biker. Getting rid of the granny bike beach cruiser. And I need a small lock for the bike since it’s a small frame. Thanks for the info! Also..expat Bostonian here, living in FL. Not a whole lot of mountains, but def a whole lot of loser thieves…

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