How to lock bike with chain lock comes down to one fixed sequence. It requires an immovable anchor, a loop through the main frame and rear wheel, almost no slack, and every link held off the ground. The practical guide to bike chain locks gives the short overview of choosing and using a chain; this article goes deep on the lock-up itself. The gap is considerable: in a study of approximately 8,500 London bicycle-locking events, researchers rated just 20 percent as locked in a secure way1. Each of the six steps here works as an inspection that takes seconds at the bicycle rack.
Quick Answer
What is the correct way to lock a bicycle with a chain lock?
Pass the chain around an immovable anchor, then through the main frame and the rear wheel, and close it with almost no slack. Hold the links and the lockhead off the pavement, with the keyhole facing downward. In a survey of Montreal cyclists published in 2015, wheels accounted for 20.1% of reported parts thefts2, which is why the rear wheel belongs inside the loop.
Key Takeaways
- Anchor first: in the same Montreal survey, 20.5% of theft victims reported that the bicycle was simply picked up and moved2. An immovable anchor stops a locked bicycle going the same way.
- Loop the main frame and the rear wheel together. A policing guide warns that a bicycle locked by the wheel alone may leave only that wheel behind1.
- Take up slack with an extra wrap around the anchor. Each wrap around a 3-inch rack tube uses about 24 cm of chain3, so length matters.
- Thicker steel doesn't fix a poor lock-up: only 20 percent of observed London locking events were considered secure1.
- Protect the front wheel when the risk justifies it. Germany's insurers' association advises two locks so the frame and wheels are secured separately4.
How to Lock Bike With Chain Lock: What to Check First
A chain lock only functions properly when its length matches the anchors the cyclist actually encounters. A long enough chain can pass through both wheels and the frame and attach the bicycle to an immovable object5. Length has a cost, though: compared with other lock types, chains tend to be the heaviest solution, especially long and tough ones5.
A security chain is a run of hardened steel links, usually inside a fabric sleeve, closed by a lockhead at one end. Before the first lock-up, three preliminary inspections decide whether the six steps will work in everyday practice.
- Usable length: the chain must encircle the anchor, a main frame tube and the rear rim with a little to spare.
- Lockhead access: the key must turn with the chain pulled tight, so practise the closing movement at home first.
- Usual anchors: note the bicycle rack or signpost at work, at home and at the shops, because tube diameter changes how much chain each wrap consumes.
Tube diameter is easy to underestimate. Portland's rack permit allows rack tubing up to a 3-inch outside diameter3, and one full wrap around tubing of that diameter consumes about 24 cm of chain. Iowa's road specification calls for round steel sign posts of at least 2 3/8 inch diameter6, and each wrap around one consumes approximately 19 cm. Link thickness and the fabric sleeve increase both figures.
| Chain | Length | Link size | Weight | Left after one wrap on a 2 3/8-inch post | Left after one wrap on a 3-inch rack tube |
|---|---|---|---|---|---|
| Viking Gold 90 | 90 cm | 10 x 10 mm square | 2.5 kg | about 71 cm | about 66 cm |
| Viking Gold 110 | 110 cm | 10 x 10 mm square | 2.8 kg | about 91 cm | about 86 cm |
| Viking Gold 140 | 140 cm | 10 x 10 mm square | 3.4 kg | about 121 cm | about 116 cm |
Seatylock's arithmetic is simple: the anchor's circumference, pi times its diameter, comes off the chain's length for every wrap3. The Viking Gold 110 keeps approximately 86 cm for the frame and wheel after one wrap on a 3-inch tube3. That margin decides whether the rear rim still fits inside the loop at a thick municipal bicycle rack.
For a cyclist who encounters thick racks every day, length is a security feature, because a short chain forces the rear wheel out of the loop.
A longer chain also has to travel with the bicycle between destinations, and the trade-offs of frame wraps, holders and bags are compared in carrying a chain without rattle.
Step 1: Choose an Immovable Anchor
An immovable anchor is a fixed object, such as a bolted steel rack or a signpost set in concrete, that resists lifting, unbolting or sliding while the chain is closed. Germany's insurers' association lists it among five basic tips: the bicycle should be secured to a fixed object such as a bicycle stand4.
Skipping the anchor eliminates the entire purpose of the chain. Merely locking the frame to the wheel is not recommended, because the entire bicycle can still be lifted and carried away or put into a vehicle5. Among theft victims in a survey of Montreal cyclists published in 2015, 20.5% reported that the bicycle was simply picked up and moved2. For a locked bicycle, an immovable anchor closes that route.
Some anchors only appear fixed. The policing guide on bicycle theft describes thieves lifting the bike and lock over the top of a post, and adds that posts are sometimes poorly anchored1. Sheldon Brown's lock notes add that some posts can be lifted out of the ground, and that thieves have cut racks and taped over the cuts7.
- Shake it: grip the anchor and pull. Any movement at the base eliminates it.
- Check the top: a post with a removable sign, or an open end, lets the whole loop slide off. A closed hoop or a loop rack has no top to clear.
- Inspect the tube: look for tape, fresh welds or loose bolts at the base.
- Pick a visible spot: the same insurers' list advises parking where busy, well-lit places deter thieves4.
Verification takes one glance: if the anchor survives the shake, has a closed top and sits in view, it passes. Wooden rails, thin fences and small trees fail, because cutting them takes less effort than cutting hardened links.
The anchor sets the ceiling for everything that follows: the strongest chain in the city is only as secure as the object it surrounds.
Step 2: Route the Chain Through the Frame and Rear Wheel
The chain goes through the rear wheel inside the rear triangle, around a main frame tube, and around the anchor, all in one closed loop. The rear triangle is the part of the frame formed by the seat tube, the seat stays and the chainstays, which together hold the rear wheel.
Both halves of that loop matter. A bicycle locked by the wheel alone may leave only that wheel behind, while one locked by the frame alone may lose its wheels1. The same guide reports research on 180 possible ways to lock a two-wheeled bicycle to a standard stand, of which just 23 were rated as secure1.
"It would be a lot of work to steal a frame without a usable rear wheel, the most expensive part of a bike after the frame."
Sheldon Brown, bicycle mechanic and technical writer, Lock Strategy, revised by John Allen7
Sheldon Brown's notes also explain why the rear triangle works as a capture point. A lock around the rear rim, inside the triangle, holds a wheel that cannot be pulled back through the frame7.
- Position the bicycle: roll it alongside the anchor, right side toward the rack, which makes removing drivetrain parts harder7.
- Thread the rim: feed the chain end through the rear wheel, inside the rear triangle, just ahead of the seat tube.
- Collect the frame: bring the chain around the seat tube or the down tube, never a seat post, saddle rail or rack bolt.
- Close around the anchor: pass the chain around the anchor and seat the end in the lockhead.
To verify the routing, pull the rear wheel sideways; if the chain catches the rim and the frame tube at the same time, the loop is correct. A loop that catches only the tire can slip off once the tire is deflated or cut.
One loop that holds both the frame and the rear wheel protects the two most valuable parts with a single lock, which is the best return any chain can give.
Step 3: Remove Excess Slack
Slack means the loose chain left hanging once the loop is closed, and it is the working room an attacker needs. The bicycle theft guide describes thieves using the gap left by a loosely fitted lock to insert jacks or bars and lever the lock apart1.
A slack chain also turns the bicycle into a tool, and the same guide notes that thieves will rotate the frame itself against the stand as a lever1. In the Montreal survey, 2.3% of theft victims named crowbars as the method used2, a small share, but one that slack makes easier.
- Wrap the anchor: take one extra turn around the anchor before closing. On a 3-inch rack tube, that wrap absorbs about 24 cm of chain3.
- Wrap the frame: if chain still hangs loosely, take an additional turn around the seat tube instead.
- Pull before closing: draw the chain tight by hand, then seat the end in the lockhead.
Verification is a lifting test: grasp the loop between the frame and the anchor and pull it away from both. A correctly tightened chain moves no more than a hand's width, and the bicycle stays tight against the anchor.
A chain that never gets tight on a cyclist's usual bicycle rack is a sizing indicator, not a technique failure. A shorter length suits a thin post, while a thick municipal hoop rewards the extra reach.
Slack is the one weakness a rider can remove for free, so a tight loop matters more than any upgrade bought later.
Step 4: Keep the Links and the Lockhead Off the Ground
Every link and the lockhead should rest on the frame or the anchor, never on the pavement. A chain lying on the ground gives an attacker a hard surface to strike against, and the policing guide on bicycle theft names that exact risk.
"If a cyclist locks a bicycle leaving the chain or lock touching the ground, thieves may use a hammer and chisel to split the securing chain or lock."
Shane D. Johnson, Aiden Sidebottom and Adam Thorpe, Bicycle Theft, Problem-Specific Guides Series No. 52, ASU Center for Problem-Oriented Policing1
The lockhead is the body that holds the locking cylinder and receives the free end of the chain. It is the component a cyclist handles most, and the component an attacker examines first.
- Lift the loop: after Step 3, raise any low section so it rests across the chainstay or the anchor tube.
- Raise the lockhead: rotate the closed loop until the lockhead sits up against a frame tube, at or above the height of the rear hub.
- Face the keyhole down: Sheldon Brown's advice is to face the keyhole down so water doesn't run into it7.
The visual inspection is quick: walk around the bicycle and look for any chain touching the pavement. A slack loop that sags to the ground fails both this step and Step 3, so the two corrections are usually the same additional wrap.
The fabric sleeve on the Viking Gold chains also assists here. It shields paintwork from scratches, so the links can rest against the frame tubes instead of hanging clear of them, and the lock-up looks tidy rather than tangled.
Height costs nothing and removes an entire attack method, so a chain that touches the ground is a lock-up that has not been finished.
Step 5: Reduce Tool Access to the Chain
A finished lock-up leaves no easy grip for a cutting tool: the chain stays taut, high and close to the frame, with the lockhead tucked against a tube. The theft guide lists tin snips, bolt cutters, hacksaws and angle grinders as tools thieves use to cut through locks and chains1.
Cutting is a genuine but minority method in the survey data. In the Montreal study, 10.3% of theft victims named bolt cutters and 4.5% named hacksaws, while 52.3% did not know how the theft happened2.
Bolt cutters depend on handle length. Wikipedia's entry states that "a typical bolt cutter yields 20 kilonewtons (4,500 lbf) of cutting force for a 250 newtons (56 lbf) force on the handles"8. By Seatylock's reading, that 80 to 1 ratio needs room for the handles to swing. By Seatylock's reading, a chain pulled tight against the frame, with no loop hanging free, gives those handles less room and the jaws fewer places to bite.
- Tuck the loop inside the frame: where possible, keep the links within the rear triangle rather than outside the wheel.
- Close against a tube: the lockhead should sit tight to the frame, with no gap behind it.
- Turn the drive side in: right side toward the anchor, as in Step 2.
Technique reduces access, but steel decides how long a cut takes. Link diameter, hardening and shape are explained in chain lock link thickness, which covers what each size class means against hand tools. The wider question of what makes a chain hard to cut is answered in heavy duty chain locks.
A tight, high chain doesn't make a lock cut-proof; by Seatylock's reading, it leaves a cutting tool less room to work.
Step 6: Add Front-Wheel Protection When the Risk Justifies It
A single chain through the frame and rear wheel leaves the front wheel unprotected. Add a second layer when the bicycle is valuable, the stay is lengthy, or thefts are frequent in the area. The policing guide warns that when a cyclist locks only the frame, a thief may remove a wheel or wheels1.
A quick-release skewer is a hub clamp with a cam lever that lets a wheel come off without tools. Sheldon Brown notes that quick releases are great for fast wheel changes during races, and also great for thieves7.
Option A: a second lock on the front wheel
Two locks of different types are the guide's advice for maximum security, because a thief then needs two different tools1. Germany's insurers' association gives the same tip: two locks let the frame and wheels be secured separately4.
Sheldon Brown describes the classic pairing, with a cable holding the front wheel to the frame and a U-lock on the rear wheel and frame7. With a chain as the main lock, the second lock can be a U-lock through the front wheel and fork. A looped cable such as the Cable Loop 120 lets that U-lock reach a front rim that sits awkwardly far from the frame.
Option B: secure the wheel fixings
Replacing the front quick release with a keyed fastener stops the wheel coming off by hand. Axle Bolts replace standard skewers or hex bolts on compatible hubs and need a coded key tool to remove. The policing guide notes that thieves know how to undo bolts and quick-release mechanisms1, which a coded fastener is designed to make harder without the matching key tool.
Keyed fixings suit cyclists who prefer to carry a single lock. The front wheel then needs the coded key tool to come off, while the chain secures the frame, the rear wheel and the anchor together.
Choosing between the options follows the parking risk, and matching protection to bicycle value, parking time and location is covered in matching chain security to risk.
A quick-release front wheel comes off without tools7, so a second layer pays off whenever the bicycle stays outside for hours.
Common Chain Lock Mistakes to Avoid
A common mistake is locking only part of the bicycle. In observations of approximately 8,500 London locking events, 19 percent locked only the frame to the stand, and in 87 percent of cases cyclists used only one lock1.
| Mistake | What it allows | Fix |
|---|---|---|
| Chain through the front wheel only | Wheel removed, frame taken; the wheel may be all that is left | Route through the rear wheel and a main frame tube (Step 2) |
| Frame locked to its own wheel, no anchor | Whole bicycle lifted and carried away | Close the loop around an immovable anchor (Step 1) |
| Anchor with an open top or a loose base | Bicycle and lock lifted over the top of the post | Shake the anchor and pick a closed hoop (Step 1) |
| Long loop left hanging | Room for a bar or jack; frame used as a lever | Extra wrap around the anchor or seat tube (Step 3) |
| Chain or lockhead on the pavement | Hammer and chisel against a hard surface | Lift the loop and raise the lockhead (Step 4) |
| Chain around the seat post or saddle rails | Loop freed by removing a clamped part | Use the seat tube or down tube (Step 2) |
Most of these mistakes share a cause: the cyclist locks to whatever is nearest instead of following the sequence. Running the six steps in order, every time, turns them into a habit that takes seconds.
Every mistake in the table costs time to correct at the rack and nothing to avoid at home. Practising the sequence once is therefore worth more than any accessory.
What a Correctly Locked Chain Looks Like
A correctly locked chain passes four inspections in one walk-around. The anchor doesn't move, the loop holds a frame tube and the rear rim, the chain lifts no more than a hand's width, and nothing touches the ground. Seatylock mapped each step to the attack route it blocks, using the policing guide's list of theft methods1 and the Montreal survey's victim reports2.
The survey shows more than one attack route in use. Among Montreal theft victims, 20.5% reported the bicycle was simply picked up and moved, while 10.3% named bolt cutters2. Lifting and cutting both happen, and different steps prevent them.
For long stays in busy areas, the stretch goal is a two-lock routine every time, following the two-lock advice of Germany's insurers' association4. A second lock only helps when it comes along, and a matched pair that opens with one key keeps the routine to a single key on the ring.
The finished lock-up is a set of independent defences, and its strength comes from completing all six, not from perfecting one.
Frequently Asked Questions
Where should a chain lock go on a bike?
Around a main frame tube and through the rear wheel, inside the rear triangle, then around an immovable anchor. A loop through one wheel alone is the weakest choice. At the University of Wisconsin in 1991, for 22 percent of cycle thefts, only the lock and the secured wheel remained1.
Should a chain lock go through the front or the rear wheel?
Through the rear wheel, the most expensive part of a bicycle after the frame7, which cannot pass back through the rear triangle once the chain holds it. In a Montreal survey published in 2015, wheels made up 20.1% of reported parts thefts2, so the front wheel needs a second lock or keyed fixings on long stops.
How tight should a bike chain lock be?
Tight enough that the loop lifts no more than a hand's width from the frame and the anchor. The policing guide describes thieves using the gap of a loosely fitted lock to lever it apart1. One extra wrap around a 3-inch rack tube takes up about 24 cm of chain3.
What can a chain lock be attached to without a bicycle rack?
A steel sign post or pole set firmly in the ground, with a top the loop cannot slide over. Iowa's road specification calls for round steel sign posts at least 2 3/8 inch in diameter6, which leaves about 71 cm of a 90 cm chain after one wrap. Trees and fences fail the shake test.
Is one chain lock enough to secure a bicycle?
For a short stop in a busy, well-lit place, one chain through the frame and rear wheel is a sound minimum. For long stays, the policing guide advises two locks of different types, and London observations found that 87 percent of locking events used only one lock1.
Limitations and Edge Cases
- Cargo, long-tail and step-through frames change the loop, because the rear triangle can sit far from the anchor. A longer chain or a second lock may then be the only way to hold both the frame and the rear wheel.
- Bolted and thru-axle wheels need a tool rather than a lever to remove, which slows a thief without stopping one, so Step 6 still applies on long stays.
- The survey shares come from a Montreal study published in 2015 and the policing guide's UK and US studies; theft methods vary by city. The choice between a chain and a U-lock is weighed in chain lock versus U-lock.
References
Methodology: every third-party figure was checked against its live source page on October 22, 2026. The chain-per-wrap arithmetic and the step-to-attack diagram are Seatylock calculations from those figures, and Viking specifications come from Seatylock's technical drawings. Michael Shenkerman holds editorial responsibility, and Shahaf Levavi, Head of Product, reviewed the article.
- ASU Center for Problem-Oriented Policing - Bicycle Theft, Problem-Specific Guides Series No. 52, by Shane D. Johnson, Aiden Sidebottom and Adam Thorpe, 2008.
- 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.
- City of Portland, Bureau of Transportation - TRN-10.09 Bicycle Rack Permit, rack design requirements, accessed October 2026.
- GDV (German Insurance Association) - Fahrraddiebstahl 2024: weniger Fälle, aber Rekordschaden, press release, accessed October 2026.
- Wikipedia - Bicycle lock, sections on U-locks and chain locks, accessed October 2026.
- Iowa Department of Transportation - Electronic Reference Library, Section 8040: Traffic Signs and Posts, materials for round steel posts, accessed October 2026.
- Sheldon Brown - Lock Strategy, by Sheldon Brown, revised by John Allen, accessed October 2026.
- Wikipedia - Bolt cutter, accessed October 2026.
Conclusion
A chain lock earns its weight only when the sequence is complete. The complete sequence is an immovable anchor, one loop through frame and rear wheel, no slack, nothing on the ground and little room for tools. Lengthy stays add a second layer for the front wheel. The steps target different attack routes, so the six together matter more than any single upgrade.
For choosing the chain itself, see the short overview in the bike chain locks guide, which summarises selection and everyday use.
