A U lock security rating means something only when an independent test house stands behind it and the exact model appears in that body's public listing. The guide to bike U-locks gives the overview of the U-lock category; this article goes one level deeper on reading the proof. It covers three independent schemes: Sold Secure in the UK, ART in the Netherlands and FUB in France. Each one uses its own ladder. ART, for example, awards between 1 and 5 stars, and its test house runs more than 20 tests on every lock it approves3.
Quick Answer
How do you read a U lock security rating?
Find the independent body, then the scheme, then the level, and confirm the exact model in that body's public database. Sold Secure grades pedal cycle locks Bronze, Silver, Gold and Diamond, and it states that Pedal Cycle Diamond is equivalent to Powered Cycle Gold1. A brand's own numbered scale proves nothing outside that brand.
Key Takeaways
- Sold Secure ranks pedal cycle locks on four grades, from Bronze to Diamond, and treats Pedal Cycle Diamond as equal to Powered Cycle Gold1.
- ART awards 1 to 5 stars, and Dutch bicycle insurers require an ART lock with at least 2 stars3.
- An ART approval is valid for 3 years and can lapse, so the database status outranks the sticker on the packaging4.
- Insurers turn grades into hard rules: one UK insurer requires a Sold Secure Gold lock for a bicycle insured above £1,5006.
- The common misconception is that a brand's own security number compares across brands. It does not; only a shared independent scheme makes two locks comparable.
Before You Begin: What a U Lock Security Rating Certifies
A U lock security rating is a level awarded by an independent body after its testers attack a specific lock model with set tools for a set time. Sold Secure states plainly that each of its pedal cycle grades is tested against tools for a specific amount of time1. The rating belongs to the model, not to the brand, and not to the lock family as a whole.
This article reads three of them. Sold Secure is an independent test house whose Pedal Cycle rating covers D-locks, chains, folding locks and even ground anchors1. ART is a Dutch foundation whose approved locks are tested by the test institute SKG-IKOB and carry a four-digit approval number3. FUB is the French cyclists' federation, and its Commission Antivol runs resistance tests on locks on the market every year5.
Gather four things before reading any badge:
- The exact model name: listings are per model and per size, so "Mason U Lock 180" and "Mason U Lock 220" are separate entries2.
- The marks on the packaging: the logo, the grade or stars, and any approval number printed beside them.
- The public search for each body: Sold Secure's approved product search, the ART website and the FUB lock database.
- The insurance policy: if the bicycle is insured, the policy wording decides which grade counts.
| Body | Country | Levels for bicycle locks | What separates the levels | Public check |
|---|---|---|---|---|
| Sold Secure | United Kingdom | Bronze, Silver, Gold, Diamond (Pedal Cycle) | Tool list and attack time for each grade | Approved product search, updated daily |
| ART | Netherlands | 1 to 5 stars | Three attack tests of rising severity | Website listing with a 4-digit approval number and status |
| FUB | France | "1 roue" and "2 roues" | Tool size: under 30 cm or under 75 cm | Search of 600+ locks tested since 2004 |
Treat these three marks as separate languages: each is precise on its own terms, and none translates word for word into another.
Step 1: Identify the Independent Body Behind the Badge
The first question is who issued the rating: an independent test house or the lock's own manufacturer. An independent body publishes one ladder for every brand it tests, which is the only thing that makes two locks comparable. ART, for example, keeps its requirements current through a technical committee of suppliers, manufacturers, the test institute, the certification body and insurers3.
Independent marks
An independent mark names its body, its scheme and its level, and the model can be found in that body's own listing. Sold Secure notes that many insurers state that a Sold Secure rated lock must be used1. That insurer link matters: a policy can name an independent grade, but it cannot name a brand's private scale.
Manufacturer scales
An internal security scale is a number, color or badge a manufacturer assigns to its own locks without an outside test. Such scales are useful for ranking one brand's catalogue from entry to top model. They fail the moment two brands are compared, because each brand chose its own top number and its own test method.
A top-of-scale badge from one brand and a top-of-scale badge from another sit on different axes. The fair comparison runs through the shared independent scheme instead: Sold Secure grade against Sold Secure grade, or ART stars against ART stars.
A badge with no named test house behind it is a design element, not evidence, and it should carry no weight in a security decision.
Step 2: Confirm the Scheme and the Category
A grade only means something once its category is known, because Sold Secure tests pedal cycles and powered cycles to separate specifications. Sold Secure states that Pedal Cycle Diamond offers the exact same security level as Powered Cycle Gold, as both use the same tools, attack methods and time limits1. So a "Gold" on a motorcycle lock and a "Gold" on a bicycle lock are different results.
The database spells the category out on every entry. Each Mason listing, for instance, reads "Pedal Cycle (Formerly Bicycle)" beside its grade, which confirms the older "Bicycle" label and the newer "Pedal Cycle" label describe the same specification2. For an e-bike, Sold Secure recommends a powered cycle rated product1, a point covered in depth in U-locks for e-bikes.
How ART splits its categories
ART ties its star levels to vehicle types rather than to a separate scheme. An ART 2 lock gives good theft protection for bicycles, an ART 3 lock suits bicycles with a high theft risk and mopeds, and ART 4 and 5 cover motorcycles3. Moped insurers require at least 3 stars, and motorcycle insurers require at least 4 stars3.
How FUB splits its levels
FUB uses just two approval levels for bicycle locks, named after wheels. The "2 roues" level is the one insurers require, according to the federation's own description of its tests5. A "1 roue" lock is therefore a lighter-duty result, even when the logo looks similar on the box.
Reading the category first prevents a serious error: buying a lock graded for the wrong kind of vehicle.
Step 3: Read the Level on Its Own Ladder
Each scheme defines its levels by the tools used and the time the lock must resist, so a level only makes sense against its own ladder. Sold Secure's Pedal Cycle grades run from Bronze to Diamond, and its Diamond test adds heavier tools, including some power tools and machine-based testing1. ART and FUB describe their levels in the same terms: tool type and resistance time.
| Grade | Threat level | Parking environment | Attack test |
|---|---|---|---|
| Bronze | Opportunistic thief | Short stop in a low-risk area, such as a cafe or shop | Short attack with a single, easily concealed hand tool |
| Silver | More determined thief | Lower-value bicycle in a medium-risk town centre | Enhanced tool list |
| Gold | Dedicated bicycle thief | High-value bicycle or a high-risk big city or university town | Extended attack with heavy-duty tools |
| Diamond | Most determined bicycle thief | Very high-value bicycle in a very high-risk area | Heavier tools, some power tools and machine-based testing |
ART runs three attack tests. For 1 or 2 stars, the lock must resist opening attempts with simple tools for a few minutes. For 3 or 4 stars, the tools are specific and the attack is often brute force. For 5 stars, the attack times are longer and the tools are heavier3.
FUB describes its two levels by tool size. A "1 roue" lock resists discreet tools under 30 cm for a short time, while a "2 roues" lock resists more aggressive tools under 75 cm5. The size limit tracks discretion: FUB calls the shorter tools discreet and the longer ones more aggressive but less discreet5.
Set side by side, the four ladders show how little translation is published. Across all four scales, Sold Secure's Pedal Cycle Diamond and Powered Cycle Gold form the only pair that any of the three bodies declares equal in its level definitions1. Any claim that "ART 3 equals Sold Secure Gold" is the writer's estimate, not a certified fact.
The level a U-lock needs is set by where and how long the bicycle stands, so read the environment column before the medal name.
Step 4: Verify the Exact Model in the Public Database
A certification mark on a box is a claim; a current listing in the certifying body's database is the proof. Sold Secure updates its pedal cycle listings daily and amends any product that no longer achieves its grade. It also asks buyers to confirm a product is currently rated to the grade their insurer specifies1. Search by brand, then match the model and the size exactly.
Reading an ART listing
An approved ART lock always carries the ART mark with its star count and a four-digit approval number, and the website shows it as approved4. An approval is valid for 3 years and can be extended by another 3 years after part of the tests are repeated4. A listing marked "Vervallen" (lapsed) means the lock has not been approved since that date.
ART gives these reasons a lock can lapse. The manufacturer withdrew it, it no longer meets the requirements, the holder did not meet its obligations, or it is no longer made or imported4. The sticker on an old box cannot show any of those changes.
Reading a FUB listing
FUB's search engine compares more than 600 locks the federation has tested since 20045. Search the model there, and read the wheel symbol beside it: one wheel or two.
The same check works on any U lock certification. A Sold Secure database search for Seatylock on October 6, 2026 returned four U-lock entries: the Mason U Lock 140, 180, 220 and 300, each graded Pedal Cycle Diamond2. One family, four sizes, one grade: the choice between them is about reach and weight, not Sold Secure grade. A rider who needs the long Mason 300 for a thick post gives up no grade against the shortest size. The U-lock size guide covers how to pick the reach.
If the exact model and size cannot be found in the body's own search, the rating should be treated as unproven, whatever the packaging says.
Step 5: Match the Rating to the Insurer and the Parking Risk
Insurers convert ratings into hard minimums, and their wording overrides any general advice. Sundays Insurance requires a Sold Secure Gold lock for a bicycle insured above £1,500, and Silver or better at £1,499 or less6. It approves Bronze only for a bicycle insured under £2506.
The same guide warns that using a Silver or Bronze lock where Gold is required, or a lock with no Sold Secure rating, could invalidate a claim6. In the Netherlands, bicycle insurers require an ART lock with at least 2 stars3. ART adds a useful rule for timing: if a policy started while the lock was approved, that approval holds for the whole policy term, even if it lapses later4.
| Who sets the rule | Scheme | Minimum level | Condition |
|---|---|---|---|
| Sundays Insurance (UK) | Sold Secure | Gold | Bicycle insured above £1,500 |
| Sundays Insurance (UK) | Sold Secure | Silver | Bicycle insured at £1,499 or less |
| Dutch bicycle insurers | ART | 2 stars | Insured bicycle |
| Dutch moped insurers | ART | 3 stars | Insured moped |
| Insurers referenced by FUB | FUB | "2 roues" | Insured bicycle |
Parking risk sets a second minimum. Sold Secure matches Gold to a high-value bicycle or a high-risk place such as a big city or university town. It matches Diamond to a very high-value bicycle kept in a very high-risk area1. A bicycle left all day at a station in a big city meets the Gold description on location alone, whatever it cost.
When the policy and the parking spot point to different grades, the stricter of the two sets the minimum.
Step 6: Check What the Rating Does Not Measure
A rating records whether one lock resists a set attack in a lab; it does not measure how that lock is used on the street. A 2008 US Department of Justice guide for police set out a plain definition of a secure lock:
"By current standards, a lock is considered 'secure' if it can withstand an attack lasting 3 minutes or more by a thief using readily available hand tools."8
Shane D. Johnson, Aiden Sidebottom and Adam Thorpe, Bicycle Theft, Problem-Oriented Guides for Police No. 52, US Department of Justice COPS Office (2008)8
The same guide reports that in about 8,500 observed London locking events, 87 percent involved only one lock and just 20 percent were locked in a way considered secure8. Sold Secure describes its Gold and Diamond tests as extended attacks with heavy-duty or heavier tools1. Even so, a Sold Secure Diamond U lock fitted loosely around a seat stay still leaves room for a thief to work.
The U-lock's known weak point
The guide defines a D or U lock as a steel bar that can be vulnerable to levering but is resistant to cutting8. It also notes that thieves use the gap left by a loosely fitted lock to insert jacks or bars and lever it apart8. The double deadbolt U-lock explainer covers how the shackle is held at both ends.
Why the U-lock format still earns its place
A survey answered by 2,039 Greater Montreal residents compared lock types against the odds of theft7. Its authors drew a clear conclusion:
"Of the different kinds of locks, U-locks are found to decrease the likeliness of bicycle theft more than other lock types."
Dea van Lierop, Michael Grimsrud and Ahmed El-Geneidy, Transportation Research at McGill University (2015)7
Among bicycles that were replaced or recovered after a theft, 71.1% were locked with U-locks at the time of the survey7. The format works best when the shackle closes tight around the frame, the rear wheel and a fixed anchor, a method set out in locking the frame and rear wheel.
A high grade buys time against a thief, and good technique decides whether the thief gets to use that time at all.
Common Mistakes When Reading a Bike U Lock Rating
Most errors in reading a bike U lock rating come from treating a medal name as if it meant the same thing everywhere. A Sold Secure U lock, an ART rated U lock and a FUB-approved lock can all be excellent, yet their labels describe different tests. The table pairs each common mistake with its cause and the check that prevents it.
| Mistake | Why it happens | The fix |
|---|---|---|
| Comparing two brands' own security numbers | Both boxes print a top-of-scale score | Compare the shared independent grade instead |
| Reading a Powered Cycle grade as a Pedal Cycle grade | Both ladders use the words Gold and Diamond | Read the category line; Pedal Cycle Diamond equals Powered Cycle Gold |
| Treating ART 3 as Sold Secure Gold | Both sit near the middle of their ladders | Read each level on its own ladder; no body publishes that match |
| Trusting the box over the database | Approvals expire, lapse or get amended | Search the exact model in the body's own listing |
| Checking the lock family, not the size | One product name covers several sizes | Confirm the exact size in the listing |
| Assuming the grade covers technique | The lab tests the lock, not the locking | Fit the shackle tight around frame, wheel and a fixed anchor |
The D lock security rating question follows the same rules, because a D-lock and a U-lock are one lock type under two names. The police guide defines them together as a D- or U-shaped steel bar8. Sold Secure lists "Bike D-Locks (U-Locks)" as a single product type under its Pedal Cycle rating, so both names share one ladder1.
Each of these mistakes ends the same way: a buyer pays for a level the lock does not hold, or under-buys for the risk the bicycle faces.
What a Verified U Lock Certification Looks Like
A verified rating reads as one complete line: body, scheme, grade, exact model and the date it was checked. For the Mason 180, that line reads Sold Secure, Pedal Cycle, Diamond, "Mason U Lock 180", confirmed in the Sold Secure database on October 6, 20262. Every part of that line can be checked by a buyer, an insurer or a retailer with one search.
Specifications belong next to the rating, because the right grade is only useful in a size that fits the bicycle and the anchor. The figures in the table come from Seatylock's published technical drawings, and the grades come from the Sold Secure listing.
| Model | Sold Secure grade | Inside size | Shackle | Weight |
|---|---|---|---|---|
| Mason 180 | Pedal Cycle Diamond | 8.5 x 18 cm | 13.7 mm, triangular | 1.07 kg |
| Mason 220 | Pedal Cycle Diamond | 11.5 x 22 cm | 14.1 mm, pentagonal | 1.53 kg |
| Mason 300 | Pedal Cycle Diamond | 11.5 x 30 cm | 14.1 mm, pentagonal | 1.72 kg |
The certificate covers the engineering half of the decision. The other half is daily use: how the lock rides on the frame, how quickly it comes off and how its weight feels on every trip. A lock left at home because it is awkward to carry protects nothing, so carry and fit deserve the same scrutiny as the grade. The Mason 180 uses a triangular shackle profile, and its frame bracket is sold separately. The wider Mason 220 trades some weight for room around a thick rack tube or post, and both hold the same Pedal Cycle Diamond grade2.
A rating line that names the body, scheme, grade, model and check date is the standard every U-lock claim should meet before money changes hands.
Frequently Asked Questions
What is the highest Sold Secure rating for a U-lock?
Pedal Cycle Diamond is the top grade in Sold Secure's Pedal Cycle category, above Gold, Silver and Bronze, and Sold Secure rates it equal to Powered Cycle Gold1. Confirm it per model: on October 6, 2026, four Mason U-lock sizes held that grade in the database2.
Is ART 3 the same as Sold Secure Gold?
None of the three bodies' published level definitions states that equivalence. ART awards 1 to 5 stars through three attack tests of rising severity3, while Sold Secure grades against its own tool lists and times. The only published bridge between ladders is Sold Secure's own match of Pedal Cycle Diamond to Powered Cycle Gold.
How long does an ART lock approval last?
An ART approval is valid for 3 years, and the holder can extend it by another 3 years after part of the tests are repeated4. A lock that loses approval is marked "Vervallen" on the ART website, together with the date the approval ended.
Which U-lock grade does bike insurance require?
The policy wording decides. One UK insurer, Sundays, requires Sold Secure Gold for a bicycle insured above £1,500 and Silver or better at £1,499 or less6. Dutch bicycle insurers ask for an ART lock with at least 2 stars, so the scheme depends on the market as well.
Does a high U lock security rating stop every theft?
No. A rating proves resistance to a set attack, not how the lock is used. In about 8,500 observed London locking events, just 20 percent were locked in a way judged secure8. A tight fit around the frame, a wheel and a fixed anchor still matters.
Limitations and Edge Cases
- Neither Sold Secure nor ART publishes a resistance time per level. Sold Secure says only that each grade is tested for a specific amount of time, so no level converts into minutes of protection1.
- The insurer minimums quoted here are examples checked on October 6, 2026. Policies change, and the wording of the policy in force always overrides them.
- Other national schemes exist beyond the three covered here. The same four checks apply to each one: the body, the category, the level and a current listing for the exact model.
References
Methodology: every third-party figure in this article comes from one of the eight independent sources listed in this section, each checked live on October 6, 2026. Lock dimensions and weights come from Seatylock's published technical drawings, the four-ladder chart is Seatylock's own synthesis of the published level definitions, and Seatylock's Head of Product reviewed the article.
- Sold Secure - Sold Secure Bike Lock Ratings: Diamond, Gold, Silver and Bronze (Pedal Cycle), accessed October 2026.
- Sold Secure - Approved product search, Pedal Cycle listings for the Mason U Lock 140, 180, 220 and 300, accessed October 6, 2026.
- Stichting ART - Over het keurmerk (About the ART quality mark), accessed October 2026.
- Stichting ART - Veelgestelde vragen (Frequently asked questions), accessed October 2026.
- FUB - Tests antivols (Lock tests), Fédération française des Usagers de la Bicyclette, accessed October 2026.
- Sundays Insurance - Which approved bike locks can I use?, cycle insurance lock guide, accessed October 2026.
- Transportation Research at McGill (TRAM) - Breaking into bicycle theft: Insights from Montreal, Canada, by Dea van Lierop, Michael Grimsrud and Ahmed El-Geneidy, International Journal of Sustainable Transportation, 2015.
- US Department of Justice, COPS Office - Bicycle Theft, Problem-Oriented Guides for Police, Problem-Specific Guides Series No. 52, by Shane D. Johnson, Aiden Sidebottom and Adam Thorpe, June 2008.
Conclusion
A U lock security rating is only as good as the four facts behind it. Those facts are an independent body, the right category, a level read on its own ladder and a current listing for the exact model. Sold Secure, ART and FUB each publish their levels and a searchable listing, and none of them publishes a translation into the others beyond Sold Secure's own Pedal-to-Powered match. Check the line, then check the fit.
For the wider context of choosing and using this lock type, see the overview in the bike U-locks guide.
