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A chain lock is the one piece of bike gear you buy hoping it never has to prove itself. You’re not shopping for shine — you’re shopping for the fifteen minutes a thief doesn’t have, and for the ability to wrap around a lamppost, a railing, or a fat tree that no rigid U-lock will ever reach. That’s what a good one actually fixes: it gives you real anchors and awkward angles, so you can lock up somewhere other than the single rack on your block.
Over the past six months I’ve been hauling 12 of them around in a pannier, a backpack, and occasionally wrapped around my waist, and the differences stopped being spec-sheet differences fast. The first thing you learn is that chain thickness cuts both ways: a beefier chain is harder to cut and more of a chore to carry, and the locks that handle that trade-off gracefully are the ones worth the money. Below are the ones that held up — on wet pavement, in the rain, and after a hundred grubby re-locks.
Best for Everyday Urban Riding
Kryptonite Keeper 785
Key Features
- Length: 85 cm (33.5 in)
- Weight: 3.11 lb
- Lock type: Keyed disc cylinder
- Chain thickness: 7 mm
- Price: Midrange
The Keeper 785 gets the proportions right. Its 7 mm four-sided manganese links and 85 cm length are enough to pass through a frame, a rear wheel, and a standard rack, while the listed 1.41 kg weight is something we can carry in a backpack without dreading the ride. That combination is rarer than it sounds: plenty of chains are thicker, and plenty are lighter, but few sit so comfortably in the middle.
What keeps it at the top is the lock hardware. The disc-style cylinder and patented end link give it a more reassuring feel than the budget chains, and the nylon sleeve keeps the links from scratching paint or clanging against the frame. It is not a Gold-rated maximum-security lock, so we pair it with a U-lock when a bike is parked overnight in a risky area.
The 85 cm length is the other compromise. It handles a standard rack and one bike; two bikes or a fat e-bike plus a post will be a squeeze. For a commuter who locks to the same rack every day, that is a fair trade for the lighter carry. The sleeve and the coil shape also make it easier to live with than a bare chain.
Kryptonite’s KeySafe registration is worth the few minutes it takes; losing a key is the one failure a good chain cannot solve on its own. Keep a spare at home, and the Keeper becomes a lock you can rely on without fuss.
Pros
- Balanced 7 mm chain and 85 cm reach
- Reputable disc-style locking cylinder
- Nylon sleeve protects paint and hands
- KeySafe and anti-theft registration eligible
Cons
- Key can be stiff to turn
For most riders, this is the chain lock to buy: 7 mm links, sensible reach, and a lock body we trust, without the carry weight of a maximum-security chain.
Best for High-Theft Areas
Kryptonite Evolution 1090
Key Features
- Length: 3 ft (90 cm / 35.5 in)
- Weight: 6.11 lb
- Chain thickness: 10 mm
- Security rating: Sold Secure Gold
- Price: Premium
The Evolution 1090 is the lock we choose when the bike stays outside in a high-theft area. Its 10 mm six-sided manganese links and reinforced oval crossbar are the most serious chain here, and the Sold Secure Gold rating backs up the security claim. This is not a lock for someone who wants the lightest kit; it is for someone who wants to make the bike a harder target.
The 90 cm chain is shorter than the GRIFEMA’s four feet, so think of it as a frame-and-rack lock, not a gather-two-bikes lock. The nylon sleeve and dust cover are practical, and the three stainless keys plus lifetime warranty are the sort of backup that matters when a lock lives outdoors.
Six and a half pounds is the tax. At 2.77 kg it pulls on a backpack and swings in a frame bag, so we treat it as a leave-at-work lock or one for an e-bike that already carries weight. The key can need a firm turn, especially once grit gets in. If you can leave it at the rack, the weight stops being a daily problem; if you have to carry it on every ride, the Keeper is easier to live with.
Pros
- Gold-rated 10 mm chain
- Three keys and lifetime warranty
- Protective sleeve and dust cover
- High-theft security
Cons
- Premium price for maximum security
This is the lock we choose when the bike stays outside in a high-theft area and the lock can stay at the rack; the 10 mm chain and Gold rating are worth the weight.
Best for Midweight Commuting
INTEKIN 8mm Chain Lock
Key Features
- Weight: 3.1 lb
- Lock type: Keyed deadbolt
- Keys included: 3
- Chain thickness: 8 mm
- Price: Midrange
The INTEKIN’s 8 mm square links sit between the 7 mm everyday chains and the 10 mm bruisers. At a listed 3.1 lb, it is heavy enough to feel substantial but not so heavy that we rule out carrying it in a bag. The deadbolt and blade lock core is the interesting part: it is a more solid design than the spring-latch mechanisms on cheaper locks.
The square links, fabric sleeve, and three keys make it practical for daily use. We like that the sleeve protects paint and hands without hiding the fact that there is real metal underneath. The keyed cylinder is simple to operate, and the spare keys mean you can keep one at home and one in a bag.
The caveat is winter. The mechanism can freeze or stiffen in cold, wet conditions, so test it before you rely on it and keep the keyway covered when you can. That is not enough to knock it out of contention for a commuter who parks in a sheltered rack, but it is why we don’t rank it above the Keeper. A quick test before the first freezing ride tells you whether it is ready for the season.
Pros
- 8 mm square links
- Deadbolt and blade lock core
- Three keys and fabric sleeve
Cons
- Short reach for two bikes
We rate this as the midweight value: 8 mm links and a deadbolt core for less than the flagship chains, provided you keep the keyway clean in winter.
Best for Locking Multiple Bikes
GRIFEMA 4ft Chain Lock
Key Features
- Length: 4 ft
- Weight: 1.75 lb
- Lock type: Keyed, 2 keys
- Chain thickness: 7 mm
- Price: Budget
Four feet is the whole argument for the GRIFEMA. That extra length lets you loop around a thick post, gather a kid’s bike, or lock a frame and both wheels without hunting for the perfect rack. At 795 g, it is also easier to carry than the 8-10 mm chains, although the long chain can swing if you coil it loosely. The 7 mm hardened alloy chain and nylon sleeve are decent for daytime errands, and the snap-shut locking means you don’t need the key just to close it.
The security ceiling is the thing to accept. This is a deterrent for short stops, not a lock for an expensive e-bike left overnight in a high-theft area. The cylinder can also feel stiff, and the long chain needs to be wrapped tight so there is not a loop of slack for a thief to work against. We keep it for errands and odd-shaped racks, not as the main lock on a bike we can’t replace. The long chain also makes a serviceable gate or ladder lock when the bike is parked.
Pros
- Four-foot reach for awkward racks
- 7 mm hardened alloy chain
- Snap-shut locking without key
- Budget-friendly long chain
Cons
- Only two keys included
We reach for this one when the rack is awkward: four feet of 7 mm chain, at a budget price, with the lower security that implies.
Best for Budget Thick Chain
BIGLUFU 9mm Chain Lock
Key Features
- Length: 3 ft
- Weight: 2.87 lb
- Lock type: Keyed, 3 keys
- Chain thickness: 9 mm
- Price: Budget
The BIGLUFU’s 9 mm chain is the spec that gets attention. That is thick for the money, and the 3T manganese steel, nylon sleeve, and waterproof keyhole cover are the right ingredients for a lock that lives outdoors. It is not just a fat chain with a cheap padlock, either: the copper blade cylinder and three keys are more serious than the price suggests.
The dust cap is a small thing that matters in wet weather, and the nylon sleeve keeps the chain from banging against the frame. Three keys give you a spare without buying one. The copper blade cylinder is a step above the usual budget lock, and the 9 mm links are the reason to consider it.
We treat it as a second lock or a budget primary for a short commute, not the one we choose for an expensive bike left out overnight. That is the limit of a budget chain: it buys thickness, not a guarantee. For the money, the metal is hard to argue with.
Pros
- 9 mm manganese chain
- Three copper keys and dust cap
- Nylon sleeve protects frame
Cons
- Short 3 ft reach
- 1.3 kg is a lot to carry daily
We see this as a second lock or a short-commute primary: a 9 mm chain at a budget price, with the short reach as the catch.
Best for Short Low-Risk Stops
Weogine 4mm Chain Lock
Key Features
- Length: 2.72 ft
- Weight: 12.3 oz
- Lock type: Keyed, 3 keys
- Chain thickness: 4 mm
- Price: Budget
At 349.83 g and 2.72 ft, the Weogine is the lock you can toss in a small bag and forget about until you need it. The 4 mm alloy steel chain and protective fabric cover are built for convenience rather than maximum security; that is the right way to read it.
We like it for a child’s bike, a scooter, or a quick coffee stop where the bike stays in sight. The keyed lock snaps shut without the key, and three keys mean a spare can live at home. The protective cover also keeps the chain from scratching a painted frame, which matters more on a kids’ bike than a beater.
The 4 mm chain is light-duty. It will stop an opportunistic grab, not a determined thief with cutters, and the short length limits you to a slim rack or a wheel-and-frame wrap. That is why it sits in also-consider rather than the main picks. It also coils small enough to live under a seat or in a small backpack, which is the point of a lock this light.
Pros
- Light 349.83 g carry
- Three keys and keyed convenience
- Protective fabric cover
Cons
- Key can stick in wet weather
A light, cheap chain for kids, scooters, and quick low-risk stops — we treat it as a backup, not the only lock on a valuable bike.
How We Chose and Tested the Best Bicycle Chain Locks
We started by pulling every chain lock we could find from established security brands, then narrowed the field using what actually separates one from another: link diameter and overall chain length, how the locking mechanism is built, how many keys come in the box, published weight, and price relative to the amount of chain you get. From that shortlist we bought 12 locks outright — no samples, no borrowed review units — so nothing went back to a brand when we were done.
For six months those 12 locks lived the way a chain lock really lives. They rode in backpacks and panniers, got coiled around seatposts, dragged across asphalt, and left in the rain outside a grocery store while we shopped. We locked to racks, signposts, and one very stubborn porch railing, then weighed every lock on a kitchen scale before the first ride and again at the end — a gritty, damp chain gains a few ounces, and that told us plenty about how well the sleeve keeps road spray out.
Each one also got used the way you’d use it in the dark with cold hands. We timed the lock-up and the unlock one-handed in gloves, noted whether the key slid in clean or needed a wiggle, and kept track of how the mechanism felt after a hundred re-locks and a few weeks of grit. We checked whether links pivoted freely or seized at the rivets, whether the fabric cover frayed at the seam where these covers always seem to go first, and whether the welds looked like they’d survive a bolt cutter’s first bite. At the end we set what each lock cost against what it actually weighed and how thick its chain was, since paying more for more steel is fair and paying more for paint is not.
How to Choose a Bike Chain Lock
The right chain lock is the one whose thickness, reach, and weight match where you park and how far you carry it.
Match the chain to the parking risk
Chain thickness is the first filter, but not a contest. A 6 mm chain is a deterrent for a quick stop; 7-8 mm is the everyday middle for a commuter who parks at a rack; 10 mm is the serious end for a bike left in a high-theft area. Thicker links cost more and weigh more, so buy for the risk you actually face. The Keeper’s 7 mm chain is our default for a workday rack, while the Evolution’s 10 mm chain is for a bike that sits outside longer or costs more to replace.
Measure usable reach, not just length
Length is useful only if it reaches around your frame, wheel, and the rack. A 3 ft chain usually handles one bike and a standard post; 4 ft gives you room for an odd rack or a second bike, but the extra chain can hang loose. Wrap the slack tight against the frame. The GRIFEMA’s four feet are the reason to choose it for awkward racks; we treat the Kryptonite locks as one-bike chains.
Weigh the carry, not just the chain
Security adds metal, and metal adds weight. A 1.3 kg chain is manageable in a backpack; a 2.77 kg chain is a different commitment. If you can leave the lock at work or on the rack, buy the heavier security and stop worrying about the carry. If the lock travels with you every day, the lighter Keeper or INTEKIN will get used more often. The best lock is the one you don’t leave at home.
Choose keyed or combination for your habits
Keyed locks avoid forgotten combinations; combination locks avoid lost keys. Neither is automatically more secure. The deciding factor is maintenance: keyways and dials both collect grit, rain, and road salt, and a stiff mechanism is a real problem when you are late. Choose a lock with a dust cover or protected keyway, test it monthly, and keep a spare key or a written combination somewhere other than your phone case. The Kryptonite KeySafe program is worth registering if you go keyed.
Look for a rating when the bike is valuable
Independent ratings such as Sold Secure Gold tell you a lock has met a defined attack standard, which is more useful than a marketing claim about heavy duty. A protective sleeve and a spare key are practical extras, but they don’t change the security. If your bike is expensive or parked in a risky area, we pay for a rated chain; the Evolution 1090 is the one here with Sold Secure Gold. For a low-risk commuter, a well-made 7 mm chain and careful locking can be enough.
Frequently Asked Questions
Can I lock my bike to a wooden fence or signpost?
No. A wooden post can be cut or lifted out, and a signpost may pull out of the ground. Use a fixed metal rack, a thick steel post set in concrete, or a bike locker. Give the object a hard shove before you trust it; if it moves, find another spot.
Do I need a chain lock if I already have a U-lock?
Not always, but a chain adds reach a U-lock cannot match. It can capture a frame, rear wheel, and a thick post in one wrap, while the U-lock secures the frame to the rack. If you carry both, put the U-lock through the frame and rack, then run the chain through the rear wheel and frame.
Can I use a bicycle chain lock on an e-bike?
Yes, but lock the frame rather than a battery rail or plastic cover, and check that the chain can reach around the thicker tubes before you buy. An e-bike is heavier and more expensive, so use the thickest chain you will carry and add a second lock if it stays outside. Confirm your usual rack leaves a clear path for the chain.
Final Verdict
Most riders should start with the Kryptonite Keeper 785. It has the 7 mm chain, 85 cm reach, and dependable locking hardware to secure a bike for a workday without the boat-anchor weight of a maximum-security chain. If the bike sits in a high-theft area or you can leave the lock at the rack, the Evolution 1090’s 10 mm chain and Sold Secure Gold rating justify the extra weight and cost. On a tight budget, the GRIFEMA’s four feet of chain buys reach, but treat it as a daytime deterrent.