Bike Locks Tested Against an Angle Grinder: 12 Locks Ranked by Cut Time

Introduction

A bike lock has one measurable job: how long does it take to cut through it? Twelve locks, ranging from £6.98 to £862, were put through the same test with a ten-minute limit per lock and an angle grinder standing by.

The results split the market cleanly. Everything at the entry level fell in seconds. Locks rated Sold Secure Diamond held out for a minute or more. And the two premium locks with an anti-angle-grinder coating simply refused to be cut at all within the time allowed.

This guide covers every lock in the test, what it costs, how long it survived, and who it suits.

How We Tested and What Sold Secure Ratings Mean

Each lock was attacked with an angle grinder under a strict ten-minute cap. The tool used was deliberately low-powered rather than a workshop-grade machine, and any lock still intact when the clock ran out was recorded as unfinished. As the test moved up to coated locks, standard metal cutting discs disintegrated on contact and the discs were switched to diamond cutting discs intended for concrete.

Sold Secure is a ratings body originally set up by insurance companies to assess bike locks. Its grades run from Bronze to Diamond:

• Bronze: basic protection against less determined thieves.
• Silver: designed to stop opportunist thieves using common hand tools.
• Gold: built to resist more determined thieves using a wider range of tools over longer attacks.
• Diamond: the highest rating, awarded to locks that survive the toughest attacks, including powerful specialist tools such as angle grinders.

A grade is not a stopwatch. Two Bronze-rated locks in this test fell in nine seconds, while one Diamond-rated lock was through in 55 seconds. The rating describes the level of attack a lock is designed for, not a guaranteed cut time.

Entry-Level Locks

This group covers the cheapest locks in the test. None of them survived longer than 53 seconds, and one did not need an angle grinder at all.

Sprogut

The Sprogut is the least expensive lock here at £6.98, and it never required a grinder. Bolt cutters went straight through it in 14 seconds, making it the quickest defeat of the entire test.

It makes sense only as a visible deterrent for very short stops in low-risk places, not as a security product.

Sportneer 1999

Also sold through Amazon, the Sportneer 1999 took 53 seconds to cut, the longest of the entry-level group. Its arms lock into place, so getting through it requires two separate cuts rather than one, and the shackle resisted bending far better than the cheaper locks around it.

That double-cut design is the main reason it outlasted everything else at this level.

OnGuard Rottweiler

The OnGuard Rottweiler carries a Sold Secure Bronze rating and costs £24.99. It was defeated by bolt cutters in 9 seconds.

Bronze is the entry grade, and the result matches it: basic protection against less determined thieves.

Kryptonite Original Keeper

The Kryptonite Original Keeper is also Sold Secure Bronze rated and costs £30. It was cut in 9 seconds, matching the Rottweiler almost exactly despite the higher price.

Like the rest of this group, it suits quick errands in low-risk locations rather than leaving a bike unattended for long periods.

Mid-Range Locks Around £50 to £62

This is where cut times start to stretch. All three locks here carry a Gold or Diamond rating, and all three held out close to or beyond a minute.

Kryptonite Evolution

The Kryptonite Evolution is Sold Secure Gold rated and costs £50. It lasted 2 minutes 48 seconds, by far the longest of the mid-range group, although around a minute and a half of that was put down to poor cutting technique rather than the lock itself.

Gold-rated locks are built to resist more determined thieves using a wider range of tools over longer attacks, and the time reflects that step up.

OnGuard 8000 Brute

The OnGuard 8000 Brute is Sold Secure Diamond rated and costs £50, making it one of the cheapest Diamond-rated locks available. It was cut through in 55 seconds.

The Diamond grade is the top rating, but this result shows that the grade alone does not determine how long a lock holds against a grinder.

Hiplok DX

The Hiplok DX is Sold Secure Diamond rated and costs £61.99. It is designed to be worn on the body while riding rather than carried in a bag, and it was cut in 53 seconds.

Its appeal is as much about carrying comfort as cut time.

Upper Mid-Range Locks

Two locks, both over £80, and both noticeably harder work than anything below them.

OnGuard The Beast

The OnGuard The Beast costs £84.99 and does not carry a Sold Secure rating. It took 1 minute 4 seconds to cut, and the cutting disc set the lock alight during the attempt.

Without a Sold Secure grade there is no independent benchmark to compare it against, even though it outlasted several rated locks in the entry-level group.

Kryptonite New York Forget About It

The Kryptonite New York Forget About It is Sold Secure Diamond rated and costs £100. At 2 minutes 38 seconds it was the hardest lock in the test up to that point, and the thickness of the material destroyed the cutting disc.

That combination of a high grade and a long cut time makes it a sensible middle ground for a bike that is left in public regularly.

Angle-Grinder-Resistant Premium Locks

The three most expensive locks here are the only ones with coatings designed specifically to defeat an angle grinder. Two of them could not be cut at all within the ten-minute limit.

OnGuard Rock Solid

The OnGuard Rock Solid costs £199 and is Sold Secure Diamond rated, with a design aimed specifically at resisting angle grinders. The outer coating is intended to stop a grinder from biting into the shackle.

After a full ten minutes of cutting, the lock had a dent representing roughly 10 percent of the way through the material. The estimate for finishing the cut with the same setup was around an hour.

Hiplok DX1000

The Hiplok DX1000 costs £299 and pairs an anti-angle-grinder coating with a Sold Secure Diamond rating. Ten minutes of grinding produced no dent at all, only a slight polish on the surface.

By the end of the time limit the tool had not meaningfully penetrated the lock.

Squire Behemoth

The Squire Behemoth is the most expensive lock in the test at £862. It uses a 20 mm hardened boron alloy steel closed shackle paired with a padlock described as the world’s strongest production padlock, and it ships with two keys. It also weighs more than every other lock in the test combined.

It was defeated in 3 minutes 19 seconds, but the shackle was not the weak point. The chain was. The link is so large that getting through it is only half the job, and the lock stays in place unless the cuts are made in the right places.

Buying Advice

The test draws a clear line at around £50. Below that, every lock in this group fell in under a minute, several of them to bolt cutters rather than a grinder. From £50 upwards, cut times stretched to two minutes and beyond, and the two coated locks at £199 and £299 could not be cut within ten minutes at all.

If a bike is left unattended in public for any length of time, the practical threshold is a Sold Secure Diamond rated lock, ideally one with an anti-angle-grinder coating. A lock that survives ten minutes of grinding is a very different proposition from one that opens in nine seconds.

It is also worth checking your insurance policy before buying. Many insurers require a Sold Secure rated lock and specific locking requirements, so the grade that satisfies your cover can matter as much as the price.

Conclusion

The takeaway is simple: when a lock claims angle-grinder-resistant materials and actually delivers on that claim, it works. The OnGuard Rock Solid and the Hiplok DX1000 both did, holding out for the full ten minutes with barely a mark.

Everything below £50 in this test came down to seconds or a couple of minutes. If the bike matters, spend at the level where the cut time stops being convenient for a thief.