The OnGuard Bulldog Mini 5013TC is a very strong, high quality mini U-lock, perfect for use in low to medium crime areas. After a long search that involved reading online reviews, articles, and comments on bike forums I settled on this lock as my best choice. It has worked out well.

Any U-lock, even heavy top of the line locks from OnGuard and Kryptonite, can be cut with power tools in a few minutes. Still, those power tools make a hell of a racket, and most thieves want to avoid attention. If you live surrounded by neighbors who consider bicycle theft using power tools to be entertaining performance art, the Bulldog Mini is probably not the lock for you.

For those of us who live in lower crime areas, where the thieves use manual tools, the best mini U locks (such as the Kryptonite and OnGuard minis) can provide protection equal or superior to heavier, more expensive U-locks against brute force attacks. The mini locks don't provide enough space for a thief to insert a large metal bar or a jack, so he can't apply the force necessary to quickly break the lock. The Bulldog Mini is strong enough to resist bolt cutters and the other standard attacks. Still, one should keep in mind that a thief with a good hacksaw, some spare blades, plenty of time, and a strong arm can eventually saw through the shackle of any U lock. It is best to park your bike in a location where such activity would be noticed.

All the Bulldog Mini's surfaces are covered with plastic, to prevent scratching the bike. The lock comes with a carrying bracket that attaches to the bike frame. Five flat keys are provided, including one key with a built-in light. The 3.5" x 5.5" measurement cited in the ad describes the inside of the U locking area, not the entire lock. The lock is large enough to go around a good-sized knobby mountain bike tire and a standard parking meter post. The most recent version of the 5013TC looks a bit different from the old, with a more cylindrical crosspiece and different coloring: mostly black, with some yellow. They are good looking locks.

If you buy a mini lock, consider using bicycle guru Sheldon Brown's lock strategy. (Google "Sheldon Brown's lock strategy" for more info.) According to Brown, a U-lock should go around the rear wheel and through the rear frame triangle to the parking meter or other secure attachment. The U need not enclose any portion of the frame. The rear wheel cannot fit through the triangle, so the prospective thief must cut all the way through the rear wheel and tire -- not easy to do. The alternative to this strategy is to secure just the frame.

One lock alone will not secure both wheels. Another U-bolt would be overkill where I live. I have a 4' cable that I can loop into the Bulldog and around both wheels, but I don't usually bother with it except when there is no post to which I can attach the Bulldog. Cables can be cut by bolt cutters, so they don't provide much security anyway.
5 stars

In terms of durability and strength, this is a great lock. However, the mini size, designed to cut down on the leverage space between your bicycle and the rack, also make this a challenging fit for larger framed bikes. I have a women's Giant Cypress (a hybird) and there's no way this lock will fit around the hefty frame, the wider quick-release tire and the bike rack. The lock will fit around the frame and rack alone.

If you're concerned about securing a quick-release tire on a mountain bike or hybrid in addition to the frame (say you live in a college town where kids like to steal things regardless of value just for the heck of it) you may want to consider one of OnGuards larger locks or this lock in combination with a cable lock to secure any parts that are less tempting targets yet are quick and easy to remove. 5 stars

The newer Bulldog MINI is distinguished by TWO yellow end caps and a different mounting bracket using a metal piece on the U-lock. Apart from the bracket, OnGuard claims the difference is mostly cosmetic, but OnGuard also indicates that the anti-theft insurance and guarantee terms differ between these versions. Moreover, OnGuard flatly states that the newer version of the Bulldog MINI is the one that should be purchased if this model is desired. If/when this seller distributes the new version, the photo should be changed. Note that the new Bulldog MINI list price is $35 list price, and that is the price for which it is sold at local recreational equipment stores. So paying that much (w/ shipping) for an older version might not be the best deal. 4 stars

I am very impressed with the OnGuard Bulldog MINI. It is not too heavy, but feels very solid. It comes with a large key with an LED light, and four non-lighted spares! Also has a nice mounting bracket with very user-friendly instructions and lots of pictures.

I actually use it to lock up my Segway's "LeanSteer" frame for extra protection in shady areas. I wasn't sure if it would work, but the mounting bracket is very adjustable.

Highly recommended! 5 stars

It's been only two weeks, the lock became stuck and I can't unlock it. This is the first time I buy a product from the brand, I'm really upset.


The warranty department sent me a new one after one call. Thanks to that. I wish that it won't stuck easily like the last one. 1 star