A Sold Secure Diamond bike lock holds the top grade of the four Pedal Cycle ratings. Sold Secure describes it for very high value pedal cycles kept in very high risk areas1. Exposure time matters too: in a Montreal survey, 37.0% of bicycle thefts happened at night2. This article sits under the bike lock certifications overview and answers one buying question: which riders actually need Diamond, and what to check in a Diamond-rated U-lock.
Quick Answer
Who needs a Sold Secure Diamond bike lock?
Diamond fits a very high value bicycle kept in a very high risk area, the environment Sold Secure writes for its top Pedal Cycle grade1. For an e-bike, Sold Secure recommends a Powered Cycle rated lock and publishes Pedal Cycle Diamond as equal to Powered Cycle Gold. By Seatylock's reading, long or overnight big-city parking adds to the case when the bicycle is also very high value. Lower value bicycles on short stops are well served by Gold or Silver.
Key Takeaways
- Pedal Cycle Diamond is Sold Secure's highest bicycle grade, above Gold, Silver and Bronze, and its attack test adds some power tools and machine-based testing1.
- Diamond's published environment joins two conditions, a very high value bicycle and a very high risk area, while Gold's environment needs only one of them.
- Three UK insurers' lock clauses set the Gold-or-higher line at £1,0004, £1,5005 and above £2,5006. None of the three makes Diamond the minimum.
- For an e-bike, Pedal Cycle Diamond is the bicycle grade Sold Secure publishes as equal to Powered Cycle Gold.
- By Seatylock's reading, a top grade doesn't replace good habits: longer exposure raises theft risk2, and loosely fitted lock-ups leave room for tools7.
Diamond at a Glance: Strengths and Limits
Pedal Cycle Diamond is the top of a four-step ladder, so its strengths come from the test and its limits come from the situations it was written for. A Diamond grade answers the question of lock resistance. It doesn't answer parking time, lock fit or the bicycle's wheels. The table sets both sides out before the detail.
| Strengths of a Diamond rating | Limits of a Diamond rating |
|---|---|
| Highest Pedal Cycle grade, described for the most determined bicycle thief | Rates the lock, not how long or where the bicycle is parked |
| Attack test adds some power tools and machine-based testing to the heavy duty tools Gold faces | Protects only what passes through the shackle, so wheels outside it stay exposed |
| Published as equal to Powered Cycle Gold, which bridges bicycle and e-bike security | A Pedal Cycle listing is not a Powered Cycle listing, which an e-bike policy can name |
| Accepted wherever a policy asks for Gold or Diamond | Longer shackles add weight, from 0.97 to 1.72 kg across the Mason range |
| Checkable by product name in Sold Secure's approved-product database | Exceeds what a lower value bicycle on short stops needs |
Read the right-hand column as a set of conditions to manage, not as weaknesses of the grade. Most limits are managed by how the lock is used, not by a higher rating.
How This Assessment Was Built
Seatylock's assessment combines eight independent published sources rather than a new lab test. Sold Secure's grade descriptions and approved-product database define what Diamond means and which locks hold it1. A McGill University survey of Montreal cyclists, published in 2015 and built on 1,922 usable responses, supplies when thefts happen2. A US policing guide supplies how cyclists lock up, and three UK insurers' lock clauses show where policies draw their lines.
Seatylock's contribution is the synthesis: it joins the test house's environment wording to the survey's timing data and the insurers' value thresholds, which no single source does. Where a sentence is Seatylock's reading rather than a source's finding, the text says so.
Where Pedal Cycle Diamond Sits on the Sold Secure Scale
Pedal Cycle Diamond is the highest of Sold Secure's four bicycle grades, followed by Gold, Silver and Bronze1. Sold Secure is a UK test house whose rated locks are tested against common thieves' tools, such as bolt croppers, angle grinders and drills, for a set time1. Pedal Cycle Diamond is the grade Sold Secure describes as the highest level of resistance against the most determined bicycle thief1. Sold Secure compares its scale to Olympic medals, with Diamond at the very top for riders who need the maximum level of security.
| Pedal Cycle grade | Threat level, per Sold Secure | Environment, per Sold Secure | Attack test, per Sold Secure |
|---|---|---|---|
| Diamond | Highest level of resistance against the most determined bicycle thief | Very high value pedal cycles kept in very high risk areas | Extended tool list with heavier duty tools, including some power tools and machine-based testing |
| Gold | High level of resistance against the dedicated bicycle thief | A high value bike and/or a high-risk area like a big city or university town | Extended attack with heavy duty tools |
| Silver | Greater level of resistance against the more determined thief | Lower value pedal cycles left in a medium risk area like a local town centre | Enhanced tool list |
| Bronze | Good deterrent against the opportunistic thief | A short time in a low risk area like a cafe or shop | Short attack with a single, easily concealed hand tool |
What Separates Diamond From Gold?
The gap between the top two grades is the tool list. Sold Secure tests Gold against an extended attack with heavy duty tools, and describes it as an in-depth test with fewer tools than Diamond1. Diamond moves to heavier duty tools and adds some power tools and machine-based testing. The public pages name each tier of tools, not the exact minutes.
Why Diamond's Environment Is Stricter Than Gold's
By Seatylock's reading of Sold Secure's wording, the environments carry a detail that is easy to miss. Gold's environment reads "a high value bike and/or" a high-risk area, so either condition is enough. Diamond's reads very high value pedal cycles kept in very high risk areas1, which joins both conditions and raises each one a step. By Seatylock's reading, Diamond is the grade for stacked risk, where an expensive bicycle and an exposed location come together.
How to Confirm a Diamond Listing Is Current
A grade printed on packaging proves less than a current database entry. Sold Secure asks buyers to check its product search to verify that a product is currently rated to the grade an insurer names1. In November 2026 the database lists four Seatylock products at Pedal Cycle Diamond: the Mason U Lock 140, 180, 220 and 3003. Searching by product name before buying, and again before filing a claim, settles the question in a minute.
Diamond is a defined grade with a published environment. The useful question is not whether Diamond is the strongest grade, but whether the bicycle and the parking spot match the environment Diamond was written for.
Who Needs a Sold Secure Diamond Bike Lock?
By Seatylock's reading, a Sold Secure Diamond bike lock earns its place when a very high value bicycle, a very high risk location and long exposure come together. Sold Secure's own rule of thumb is that the higher the value of the bike, the higher the Pedal Cycle rating a rider should aim for1. Each profile below carries part of that risk.
The All-Day City Commuter
A commuter who leaves a valuable bicycle at a station or office rack for a full working day gives a thief the longest daytime window. The McGill survey found that over three fifths of bicycle thefts happened during the day, when bicycles are likely to be parked at a destination other than the rider's home2. The survey recorded 32.3% of thefts in the afternoon alone. In a big city, that location already meets Gold's environment. By Seatylock's reading, a very high value bicycle left there all day is the stacked risk Diamond describes.
The Overnight Street Parker
Night is the single most common theft period in the Montreal data, at 37.0% of bicycle thefts2. The survey's authors tied longer exposure to a higher chance of theft, and many respondents commented that bicycles should not be left on the street at night.
"These factors indicate, as expected, that the longer a bicycle is exposed, the more likely it is to be stolen."
D. van Lierop, M. Grimsrud and A. El-Geneidy, McGill University researchers, Breaking into bicycle theft: Insights from Montreal, Canada2
One participant in the same survey reported a bicycle locked outside an apartment with a high security U-lock and stolen overnight2. She now brings it inside every night, which she called a nuisance. A Diamond lock raises the effort a thief needs, but indoor storage removes street exposure entirely.
The E-Bike Owner
Sold Secure recommends a Powered Cycle rated product for e-bikes, and states that Pedal Cycle Diamond products offer the exact same security level as Powered Cycle Gold1. Both are tested with the same tools, attack methods and time limits. The Powered Cycle category is Sold Secure's separate rating scheme for motorcycles and e-bikes, with two grades, Diamond and Gold. The test house points e-bike, moped and scooter owners to it. Pedal Cycle Diamond is therefore the bicycle grade Sold Secure publishes as equal to Powered Cycle Gold.
The listing still matters. A Mason U-lock is listed under Pedal Cycle, not Powered Cycle3, so an e-bike policy that names a Powered Cycle grade needs its wording checked first. Where a policy asks for a Sold Secure Gold or Diamond lock without naming the category, a Pedal Cycle Diamond U-lock holds the higher of the two named grades. Confirm that the insurer accepts a Pedal Cycle listing for an e-bike.
The Owner of a Very High Value Bicycle
Premium bicycles are not what thieves take most often. In the McGill survey, the most frequently stolen bicycles were new ones valued between $150 and $500, at 27% of the 961 stolen bicycles reported2. By Seatylock's reading, Diamond's case for a premium road, carbon gravel or cargo bike rests on the size of the loss, not on how often such bicycles are taken.
By Seatylock's reading, the commuter, overnight or high-value profile on its own points to Gold, while the e-bike case follows Sold Secure's Powered Cycle advice. Two or more together, such as an expensive e-bike parked all day at a city station, is the situation Diamond was written for.
Who Doesn't Need the Highest Bicycle Rating
A lower value bicycle parked for short stops in a town centre is well served below Diamond. Sold Secure describes Silver for lower value pedal cycles in a medium risk area like a local town centre, and Bronze for a short stop at a cafe or shop1. The Silver-level protection guide covers when that lower grade is enough.
The trade-off is size. Per Seatylock's specifications, the Mason range runs from 0.97 kg to 1.72 kg, and longer shackles take more room on the frame3. By Seatylock's reading, a Gold lock that rides on the frame every day protects more often than a Diamond lock left in the hallway. Gold also covers a high-risk area on its own, which Sold Secure describes as a big city or university town.
By Seatylock's reading, riders between the two profiles should let the insurer's clause and the parking time decide. A bicycle below very high value that never stays out after dark and never sits long at a rack is a Gold or Silver case.
Diamond is not a default for every rider. It is the answer when the bicycle's value and its exposure both sit at the top of the scale.
What to Check in a Diamond Certified Bike Lock
Once a rider needs Diamond, the grade stops being the differentiator, and fit, carry and coverage decide the choice. In November 2026 the four Seatylock locks listed at Pedal Cycle Diamond are all U-locks, the Mason 140, 180, 220 and 3003. The checks below apply to any Diamond certified bike lock a rider compares.
Does the Shackle Fit the Anchors on the Route?
Fit comes first because a lock that can't close around the frame and the anchor protects nothing. Inside dimensions are the width and length of the clear space inside a U-lock's shackle, and they decide which tubes, tires and posts fit together in one lock-up. A shackle that is far larger than the lock-up also leaves room for tools. The policing guide notes that thieves use the gap left by a loosely fitted lock to insert jacks or bars and lever the lock apart7.
"The best U-locks, if you must carry one on the bike, are the smallest."
Sheldon Brown, bicycle mechanic and technical writer, Lock Strategy8
Brown's reasoning is that a small shackle leaves limited room for an automotive jack and less purchase for levering attacks8. By Seatylock's reading, the right size is the smallest shackle that still closes around the frame and the usual anchor without forcing.
| Lock | Sold Secure listing, November 2026 | Inside width x length | Shackle | Weight | Typical fit, Seatylock guidance |
|---|---|---|---|---|---|
| Mason 140 | Pedal Cycle Diamond | 8.5 x 14 cm | 13.7 mm triangular | 0.97 kg | Frame to a slim rack tube or post |
| Mason 180 | Pedal Cycle Diamond | 8.5 x 18 cm | 13.7 mm triangular | 1.07 kg | Frame and rear rim to a rack tube |
| Mason 220 | Pedal Cycle Diamond | 11.5 x 22 cm | 14.1 mm pentagonal | 1.53 kg | Wider tires and thicker tubes |
| Mason 300 | Pedal Cycle Diamond | 11.5 x 30 cm | 14.1 mm pentagonal | 1.72 kg | Longest reach for bulky frames and fixtures |
The four sizes share one grade, so the choice between them is a carry decision. By Seatylock's comparison of its published specifications, the Mason 300 has more than twice the inside length of the Mason 140 for about 77 percent more weight. The listings come from the Sold Secure database3, and the dimensions and weights from Seatylock's product specifications. Extra length helps only when the lock-up needs it, such as a rim plus a frame tube plus a rack.
Will It Ride on the Bicycle Every Day?
Carry decides whether the lock comes along at all. Each Mason U-lock fits a frame bracket that straps to the seat tube or another frame tube. Seatylock describes its mounting bracket as a rattle-free docking point with quick release. The Mason product pages list the mounting bracket as sold separately, so a rider who plans to carry on the frame adds it at purchase. The lightest Diamond option in the range is the Mason 140 at under 1 kg, per Seatylock's specifications and its Diamond listing3.
The experience half of the decision is practical. A lock that rides in a bracket on the frame gets taken on the short ride as well as the commute, because nobody has to remember it. Seatylock's view is that ease of use outweighs a few hundred grams of steel in daily carry.
How Is the Shackle Held in the Lock Body?
The locking mechanism is the second hardware check after the grade. The Mason product pages describe a double deadbolt locking mechanism for protection against twist attacks, which means the shackle is held in the lock body at both ends. The Mason 140 and 180 use a triangular hardened steel shackle, and the 220 and 300 a pentagonal one, per Seatylock's specifications. For all four, the independent proof remains the same Pedal Cycle Diamond listing3.
What Stays Outside the Shackle?
A Diamond U-lock protects the parts that pass through it and nothing else. The policing guide warns that if a cyclist locks only the frame, a thief may remove a wheel or wheels7. A steel cable such as the Cable Loop can carry the front wheel back to the U-lock. One insurer's guide notes that an accessory cable is not Sold Secure rated, and under Pedal Cover's policy a theft made by cutting the cable alone would not be covered5.
That makes the cable a wheel deterrent, not part of the rated lock-up. The frame and the anchor belong inside the Diamond shackle every time.
Choose the smallest Diamond shackle that closes around the frame and the usual anchor, and plan the wheels separately. A closely fitted lock-up gets more from a Diamond grade than a longer shackle does.
Bike Value, Insurance and the Sold Secure Pedal Cycle Diamond Grade
In the three UK insurer clauses compared here, two clauses name the Sold Secure Pedal Cycle Diamond grade alongside Gold, AssetSure names Gold, and none requires Diamond on its own. Cycleplan asks for a Gold or Diamond rated lock once a bicycle's insured value reaches £1,0004. Pedal Cover asks for a Sold Secure Gold or Diamond lock from £1,5005. AssetSure names a Gold rated lock above £2,500 of insured value6.
Set side by side, the clauses show two things. The value at which a policy first asks for Gold or higher varies by a factor of 2.5 across the three, from £1,000 to above £2,50046. In none of them is Diamond the minimum. Two accept Gold or Diamond together, and AssetSure names Gold, adding that a Diamond grade offers even greater protection6.
A Worked Example: One Bicycle, Three Clauses
A bicycle insured for £2,000 needs a Gold or Diamond lock under Cycleplan's and Pedal Cover's clauses45. Under AssetSure's guide, the same value sits in the Silver band of £1,501 to £2,5006. A Diamond lock satisfies all three clauses at once. A Silver lock satisfies one of them, which is why the policy schedule, not an online rule of thumb, sets the floor.
Sold Secure gives the same advice from the testing side. It says providers will often specify the grade they require, and that the required rating is usually stated in the policy documents1. The insurance lock rating guide walks through reading that clause.
Treat the policy as the minimum and the parking as the reason to exceed it. In these three clauses, Diamond is never the grade the insurer demands. By Seatylock's reading, it's the grade high exposure justifies.
Alternatives to a Diamond Lock
The main alternative to Diamond is Pedal Cycle Gold, chosen when only one risk factor applies. A second lock of a different type covers cases that a single grade cannot. Each option answers a different part of the risk.
Pedal Cycle Gold
Gold is tested against an extended attack with heavy duty tools. Sold Secure describes it for a high value bike and/or a high-risk area like a big city1. Every insurer clause compared here accepts Gold at its highest value band. The Sold Secure Gold explainer covers that grade in depth, including where it falls short of Diamond.
A Second Lock of a Different Type
Two different locks force a thief to bring two different tools. In around 8,500 London locking events, cyclists used only one lock in 87 percent of cases, and just 20 percent locked in a way considered secure7. The policing guide advises two locks of different types for maximum security, which increases the effort a theft takes7. A Gold lock paired with a different second lock is one answer for a rider whose bicycle sits out for long periods.
Other Independent Ratings
Sold Secure is one of several independent schemes. The Dutch ART scheme and the French FUB scheme grade locks on their own scales. The security ratings comparison sets those schemes next to Sold Secure for riders whose insurer names a different standard.
Upgrade the grade when value and risk both sit at the top. Add a second lock, or bring the bicycle inside, when the problem is time, because longer exposure raises the chance of theft.
Final Verdict: Diamond, Gold or a Second Lock?
A Sold Secure Diamond bike lock is the right choice for a very high value bicycle kept in a very high risk area, as Sold Secure writes1. It is also the bicycle grade Sold Secure publishes as equal to Powered Cycle Gold, which matters for an e-bike parked in public. Its strengths are Sold Secure's most in-depth bicycle attack test and acceptance by every Gold-or-Diamond clause.
Its limits are physical and practical. A longer shackle adds weight and bulk, the lock protects only what passes through the shackle, and it does not shorten the time a bicycle sits outside. If the bicycle is very high value and parks in a very high risk area, Diamond matches Sold Secure's description. By Seatylock's reading, all-day or overnight parking strengthens that case. If only one factor applies, Gold is a sound choice, and a lock that is easy to carry is one that actually comes along.
Frequently Asked Questions
Is Sold Secure Diamond the highest bike lock rating?
Yes, for bicycles. Pedal Cycle Diamond is the top of Sold Secure's four bicycle grades, above Gold, Silver and Bronze1. Sold Secure also runs a separate Powered Cycle scheme for motorcycles and e-bikes. Its grades are Diamond and Gold, and Powered Cycle Gold equals Pedal Cycle Diamond.
Do I need a Diamond lock for an e-bike?
Sold Secure recommends a Powered Cycle rated product for an e-bike, and publishes Pedal Cycle Diamond as the same security level as Powered Cycle Gold1. If the policy names a Powered Cycle grade, check that wording first.
Does my insurer require a Sold Secure Diamond lock?
Not in the three UK clauses compared here. Of those insurers, Cycleplan asks for Gold or Diamond from £1,0004, Pedal Cover asks for Gold or Diamond from £1,5005, and AssetSure names Gold above £2,5006. The policy schedule sets the minimum, and a Diamond lock meets each of those Gold-or-higher clauses.
Is a Diamond U-lock too heavy for daily carry?
Not necessarily. The smallest Diamond-listed Mason, the 140, weighs under 1 kg per Seatylock's specifications, and Sold Secure lists all four Mason sizes at Pedal Cycle Diamond3. Choosing the smallest shackle that fits the usual anchor keeps the weight down and, by Brown's reasoning, leaves less room for levering tools.
Can a Diamond-rated lock still be defeated?
Yes. A grade measures resistance to set tools for a set time, and thieves are known to use tin snips, bolt cutters, hacksaws and angle grinders7. Exposure still matters: night accounted for 37.0% of thefts in the Montreal survey2, so long or overnight parking calls for a second lock or indoor storage.
Limitations and Edge Cases
- The theft timing figures come from one survey of Montreal cyclists published in 20152; the split between day and night may differ by city and season.
- The insurer clauses are UK policies checked in November 2026. Other countries, policies and renewal years can draw the line elsewhere or name a different scheme.
- Sold Secure publishes the tier of each tool list, not the exact minutes or tools, so this article compares grades by their published descriptions and leaves power-tool test mechanics aside.
References
Methodology: every third-party figure in this article links to the independent published source that carries it, and Mason dimensions and weights are Seatylock's published specifications. Product grades were checked in the Sold Secure database in November 2026, and Seatylock's Head of Product reviewed the article.
- Sold Secure - Sold Secure Bike Lock Ratings: Diamond, Gold, Silver and Bronze (Pedal Cycle), accessed November 2026.
- Transportation Research at McGill (TRAM) - Breaking into bicycle theft: Insights from Montreal, Canada, by D. van Lierop, M. Grimsrud and A. El-Geneidy, International Journal of Sustainable Transportation, 2015.
- Sold Secure - Approved product search, Seatylock USA LLC listings, accessed November 5, 2026.
- Cycleplan - Approved locks, cycle insurance lock requirements, accessed November 2026.
- Pedal Cover - Bicycle security guide, cycle insurance policy requirements, accessed November 2026.
- AssetSure - Choosing an Approved Bicycle Lock, bicycle insurance guidance, accessed November 2026.
- ASU Center for Problem-Oriented Policing - Bicycle Theft, Problem-Specific Guides Series No. 52, by Shane D. Johnson, Aiden Sidebottom and Adam Thorpe, 2008.
- Sheldon Brown - Lock Strategy, bicycle technical article by Sheldon Brown, accessed November 2026.
Conclusion
Sold Secure Diamond is the top bicycle grade, written for very high value bicycles kept in very high risk areas and published as equal to Powered Cycle Gold. By Seatylock's reading, it suits riders whose risks stack: an expensive bicycle or e-bike, a big-city location and long or overnight parking. Insurers in this comparison set Gold or higher as the floor, so Diamond is a choice made for exposure, and a closely fitted lock-up gets the most from it.
For how Diamond sits alongside the other grades and schemes, see the bike lock certifications overview.
