Pentagon 220 U-lock from Seatylock Review
Pentagon 220 U-lock Specs
3.3 lb (1.5 kg)
4.53 x 8.66"
Other Security Ratings:
They’ve managed to combine a super thick shackle, standard sized dimensions and high security ratings in a lock that’s not absurdly heavy.
So let’s have a look at it in more detail. In this review I’ll cover how secure it is, how easy it is to carry around and use every day and finally what the alternatives are if it’s not the right choice for you.
How secure is the Pentagon U-lock?
The Pentagon features an impressive 15.3 mm thick shackle. There are very few u-locks with thicker shackles and while (at less than 16 mm) it’s still theoretically crop-able, the patented pentagon shape of the shackle make this extremely unlikely.
In fact, we can say with a lot of confidence: this is not a lock that’s going to be defeated by bolt cutters.
The shackle is also double bolted which means that it locks into the crossbar on both sides. This provides additional protection from twisting and leverage attacks. And it also means that the shackle would need to be cut through twice (on each side) to defeat it.
The Pentagon also boasts (the pretty standard these days) anti-drilling components which makes it unlikely that a thief can simply drill through the cylinder.
All these features mean that the Pentagon is a high security lock and indeed Sold Secure have given it Gold security rating. Having said that, the Sold Secure Gold award covers a pretty broad range of security levels, so it would be nice to see an ART rating for this lock too.
But rest assured this is a very secure lock. And certainly the most secure lock that Seatylock have produced so far.
Is the Pentagon U-lock easy to carry?
At 3.75 lb (1.5 kg), the Pentagon 220 is by no means a light lock. In fact, I’d imagine most people would say it’s pretty damn heavy, weighing as it does the same as 4 cans of coke. But high security locks are heavy. And it’s actually much lighter than most other standard sized Gold rated u-locks…
I’d imagine that this is down to the 5 sided shackle of the Pentagon which allows it to use less steel without compromising security in a similar way to the Abus Granit X Plus 540, the lock which the Pentagon 220 most resembles…
But it’s still heavy! And heavy u-locks can be tricky to carry around on a daily basis. And not just because of their weight; their rigid shape is also an issue. If we carry them in a bag they take up loads of space. And if we attach them to a frame mount, because the weight is distributed away from our bike they often become unstable.
So, you can carry the Pentagon around in your bag if you like. But it’s going to be heavy and could get quite annoying. A good frame mount would be better.
The Pentagon doesn’t come with a frame mount, but Seatylock does manufacture one specifically for this u-lock that you can buy separately. I quite like this arrangement as not everyone will want to mount their u-lock on their frame. But it is an extra cost ($15) that you’ll need to factor in.
The Pentagon Mounting Bracket is similar to the Kryptonite frame mount in that it attaches to your frame with a material strap. However, it’s much more flexible, allowing you to attach the lock to your frame at a multitude of different angles.
Just like the Kryptonite frame mount though, if you don’t use the right method to attach it to your frame you won’t get it tight enough and you’ll have problems with it working loose over time. The secret is: to leave the metal bolt barely attached while you tighten the strap as much as possible by pulling it through the plastic feeder. Once it’s as tight as it will get, only then should you screw in the metal bolt to produce a really strong attachment to your frame.
This is better learnt through demonstration and Seatylock are producing a video that should explain it much better than I can!
Once attached properly, the frame mount seems reasonably robust and I didn’t have any problems while I was testing the lock. The USP of this frame mount though is that it can be slid and rotated on every plane so that you can attach the lock to your frame in many more positions than with other mounts.
If you have a frame that’s already full of other items such as water bottles and tool kits then this is clearly a big bonus! However, I couldn’t find many unusual positions that were practical and be aware that these more exotic positions tend to leave the center of gravity further from the frame which produces more strain on the mount and increases the chances that it will work loose over time.
So in the end, this is a big, heavy and rigid, high security u-lock. And these locks will always be a challenge to carry comfortably. The frame mount is quite strong and flexible though and you should be able to find a practical position on your bike.
Is the Pentagon U-lock easy to use?
The Pentagon 220 which I tested measures 22 cm long and 11.5 cm wide (8.66″ x 4.53″). This makes it a standard sized u-lock which will give you loads of options when you’re looking for somewhere to lock your bike…
You should have no problems locking your frame and one of your wheels to whichever style of bike racks you have where you live.
And because the Pentagon is actually slightly wider than other standard sized u-locks, many lamp posts and traffic lights will also provide practical and secure locking stations.
If you need something longer (for example you might want to secure 2 bikes with 1 lock), then there is also the Pentagon 300 which is the same width but 30 cm long. And if you need something smaller then there’s also the new Mason mini u-lock from Seatylock.
My Pentagon needs a good tug to separate the shackle from the body. While this is not a big issue with a new lock (you just need to learn how much force to apply), as the lock gets older and the metal invariably starts to corrode, there’s a danger that the shackle will start to really stick in the body, even to the extent that it can’t be removed!
This is a really common issue with u-locks and if you’re not careful you’ll come to unlock your bike and while the key and mechanism will work perfectly, the shackle will have fused into the body and you just won’t be able to free it. The only solution is an angle grinder and a new lock!
So my recommendation is to regularly wipe the ends of the shackle clean with a rag and apply White Lithium Grease. This will keep corrosion to a minimum and should stop the shackle fusing to the body as the lock starts to age. Really you should do this with all locks but especially locks that are already a bit “sticky” like my Pentagon.
The Pentagon comes with 3 keys and the standard code card so you can order more if you start losing them. All the Seatylock keys are internal cut keys (also known as “Sidewinder” or “Laser cut” keys). This type of key is more tricky to replicate and the mechanisms are harder to pick, so that’s another security bonus!
Like the Abus Granit X Plus 540, the mechanism is protected by an internal dust cover that’s pushed aside when the key’s inserted. They’re much easier to use than the external dust covers and do a good job of keeping water and grime out of the mechanism.
Pentagon 220 U-lock Review Summary
The Pentgon 220 is a great, standard sized, high security u-lock. It won’t be cropped by bolt cutters. The double locking shackle provides plenty of protection from leverage attacks. And while all locks can be defeated by angle grinders, 15.3 mm of steel should encourage thieves to look for easier targets!
It’s compatible with a versatile Seatylock frame mount that allows you to attach the lock to almost any position on your bike, which is great if you already have a busy frame or an unconventional set up. Although don’t forget, you’ll need to buy this frame mount separately.
And the wider than usual shackle will give you a few more locking options when you’re looking for places to leave your bike.
You should regularly grease the ends of the shackle with White Lithium Grease to prevent the shackle “fusing” into the body as the lock ages. I recommend this for all high security u-locks with thicker shackles and heavy bodies. But especially for u-locks like the Pentagon that are already a bit “stiff”.
But all in all, this a lock that will provide maximum protection for your bike, loads of carrying options and plenty of places you’ll be able to leave your bike. What’s more it’s very competitively priced when compared to similar locks from Abus or Kryptonite.
Of course, if it’s not the right lock for you, then there are always plenty of alternatives…
Alternatives to the Pentagon 220
If the Pentagon 220 isn’t exactly what you’re looking for, then there are a number of other locks which might be more suitable…
Looking for something cheaper?
There aren’t many high security, standard sized u-locks that are cheaper than the Pentagon and which I’d also recommend.
This is because most feature a poor quality construction that won’t age well!
However, I would recommend the OnGuard Pitbull Standard.
It has the same Sold Secure Gold rating, the same internal measurements and can it usually be found incredibly cheap on Amazon. You’ll also get a decent frame mount for free!
Perhaps the mechanism isn't a s good. And a slightly thinner shackle mean it’s not quite as secure as the Pentagon But it’s a great choice if you have a limited budget but still want a high security lock.
Looking for something more secure?
The Pentagon is a very secure bike lock. If you want something significantly more secure then you’re probably going to have to go smaller and thicker.
The Kryptonite New York Fahgettaboudit Mini [Amazon] has an incredible 18 mm shackle and measures just 3.25 x 6″ (8.3 x 15.3 cm) internally. It’s not just Sold Secure Bicycle Gold, it’s also Sold Secure Motorbike Gold. And it has 4/5 stars from ART.
However, despite being a mini u-lock, at 4.55 lb (2.06 kg) it’s considerably heavier than the Pentagon, offers less locking options (due to it’s size) and doesn’t come with a frame mount.
But it’s undoubtedly the most secure bike lock available today and if you’re looking for maximum protection, this is the lock for you!
Read my hands-on review of the Kryptonite New York Fahgettaboudit Mini.
Looking for something lighter?
The Litelok [Amazon] is something completely different. Made from a very strong, (but very light) material they call “Boaflexicore”, it looks more like a belt than a bike lock!
However, it has the same Sold Secure Gold rating as the Pentagon and at 2.47 lb (1.12 kg) it’s actually much lighter.
Measuring 29″ (74 cm) long, it also gives you more internal space than the Pentagon. And since it’s flexible, you’ll get more locking options too.
It’s quite expensive though and it takes a while to get used to the way it works.
But if you’re looking for the lightest high security bike lock that also gives you lot’s of places to leave your bike then this is a great choice! Read my hands-on review of the Litelok Original.
If none of these options are quite right for you, try my simple 3 step guide that guarantees to find the best lock for you and your bike!
Pentagon 220 U-lock Specs
Pentagon 220 U-lock Specs
3.3 lb (1.5 kg)
4.53 x 8.66"
Other Security Ratings:
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Last Updated on November 27, 2020 by Carl Ellis