OnGuard RockSolid review | Angle-grinder-resistant D-lock independently tested

Date reviewed: May 2025 | Tested by: John Milbank | RRP: £199.99 | Weight: 1.34kg | www.onguardlock.com

The OnGuard RockSolid 8590 on review here is primarily aimed at the bicycle market, but it’s been attracting a lot of attention from motorcyclists that have seen claims of it ‘outperforming every lock’ in angle-grinder testing, and of it taking up to 11 discs to defeat.

So we bought one.

I’ve run the RockSolid through Bennetts BikeSocial’s standard set of test criteria to find out if it lives up to the hype…

Pros & Cons

Size and weight

The OnGuard Rocksolid 8590 has been tested and certified as Sold Secure Pedal Cycle Diamond. While this independent methodology does include an angle-grinder attack (along with other tools), it’s less intensive than that required to meet the tougher Sold Secure Powered Cycle Diamond level.

Weighing 1.34kg, it’s 390g lighter than its most direct competitor, the Litelok X1 reviewed here, though that’s a bigger (and perhaps more versatile) lock, so there’s more of it.

The internal shackle size of 80x170mm is the smallest I’ve tested, even compared to the original Hiplok D1000, which was also designed for bicycles (the newer Hiplok DX1000 has the largest shackle size of any of these D-locks tested to date).

The RockSolid’s shackle is coated with a fine material that’s intended to destroy abrasive angle-grinder discs, and measures 14.8mm in diameter. The silicone coating over the top protects your bike’s paintwork and brings the outer shackle size up to 24x25mm.

Five keys are supplied, along with a code card in case you manage to lose them all. The keyway is protected from dirt by a sprung shutter.

The OnGuard RockSolid’s shackle is retained at both sides with a pair of locking pins on each, reducing the amount of rotation in it after one cut.

Resistance to attack: lock picking

While some YouTube channels might make lock picking look easy, especially when selling the creator’s own tools, it’s not a method used in typical motorcycle thefts at all, not least because the thieves typically stealing bikes don’t have the time or skill to carry out this form of attack.

To see how this compares with the other locks we’ve tested, check out our best motorcycle locks for home and away.

Resistance to attack: bolt-croppers

I tested the OnGuard RockSolid with a set of 42” bolt croppers, which left only a small dent in the shackle.

To see how this compares with the other locks we’ve tested, check out our best motorcycle locks for home and away

Resistance to attack: drill

Despite being described as ‘drill resistant’, using a standard HSS bit I was able to drill all the way into the core of the lock barrel. I was unable to open the lock after this attack, though I did it after a sustained hammer attack, which had already jammed the mechanism due to distorting the body of the lock.

A drill attack is highly unlikely to be successful, and it took a lot longer to drill out than it did to defeat the OnGuard RockSolid with other forms of attack.

To see how this compares with the other locks we’ve tested, check out our best motorcycle locks for home and away.

Resistance to attack: lump hammer

Repeated and heavy blows with a lump hammer while the lock was attached to my test bike wheel did at first appear to be causing it to fail, but despite a very sustained attack it was the outer shell that was distorting and I was unable to defeat the OnGuard RockSolid this way.

To see how this compares with the other locks we’ve tested, check out our best motorcycle locks for home and away.

Resistance to attack: angle-grinder

With some reviewers claiming they’ve burned through multiple discs cutting the OnGuard RockSolid, I was surprised to make my first cut shortly after changing the 1.0mm abrasive disc just once. Even more so on my second attempt (using a battery-powered grinder) when I managed a cut with only one disc, having used about a third of it.

Depending on the thief’s technique, more discs might be required, and if they do manage it with one disc it’s almost certain they’ll need a fresh one for the second cut that’s required to get the lock off in most cases due to the limited movement of the shackle in the lock’s body (measured to be approximately 30mm maximum).

The body of the OnGuard RockSolid has the same coating as the shackle, and proved more time-consuming to cut so is not a vulnerability.

The OnGuard RockSolid proved to be far more susceptible to a diamond disc attack. While these are less common, my testing has shown than some angle-grinder resistant locks perform significantly better than others.

To see how this compares with the other locks we’ve tested, check out our best motorcycle locks for home and away.

Bennetts BikeSocial test results

Product: OnGuard RockSolid 8590

Weight as tested: 1.34kg

Bolt cropper attack: PASS

Drill attack: PASS

Hammer attack: PASS

Angle grinder attack: AVERAGE

To see the other chains and locks tested by Bennetts BikeSocial, click here and be sure to regularly check for the discounts available through BikeSocial membership.

OnGuard RockSolid review: Verdict

For cyclists looking to save every bit of weight they can, the OnGuard RockSolid 8590 has its place, though the lack of a frame mount puts it at a disadvantage compared to some others. If you do have a way to carry it though, it’s still important to understand its limitations.

In my testing the RockSolid delivered very average resistance to angle-grinder attacks (though it's still better than a 'normal' D-lock), and the small shackle size will limit its value for most motorcyclists. I’m not sure why there’s such disparity between my results and those of some of the other reviews I’ve seen, but using my standard tools it was disappointing not to have found a new champion in motorcycle security. You can find the best angle-grinder-resistant D-locks based on our independent testing here.

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