No bike lock can make a bike impossible to steal. A good lock buys time and makes your bike a less attractive target than others nearby. The right choice depends on where you park, how long you leave the bike, what it is worth to you and how much weight you are willing to carry.
The main lock types
U-locks (D-locks)
A rigid hardened steel shackle that locks into a crossbar.
- Pros: good security for their weight; rigid shape resists many attacks; compact options leave less room for leverage tools.
- Cons: fixed shape limits what you can lock to; awkward to carry without a frame mount or bag.
- Best for: everyday urban locking to bike racks.
Chain locks
A hardened steel chain, usually in a fabric sleeve, with a padlock or integrated lock.
- Pros: flexible; can wrap around larger objects; heavier chains offer high security.
- Cons: secure chains are heavy; lighter chains are easier to cut.
- Best for: home storage, high-risk areas and locking to awkward objects.
Folding locks
Steel plates connected by rivets that fold into a compact package.
- Pros: compact and easy to carry, usually with a frame mount; more flexible than a U-lock.
- Cons: security varies widely; the rivets can be a weak point on some designs.
- Best for: riders who prioritize portability and moderate-risk locking.
Cable locks
Braided steel cables.
- Pros: light, flexible, inexpensive.
- Cons: generally easy to cut. Best used only as a secondary lock to secure wheels or accessories.
Comparison table
| Type | Security potential | Weight | Flexibility | Portability |
|---|---|---|---|---|
| U-lock | High (depends on model) | Medium | Low | Medium |
| Chain | High (heavier models) | Heavy | High | Low to medium |
| Folding | Medium to high (varies) | Medium | Medium | High |
| Cable | Low | Light | High | High |
Independent security ratings
Manufacturers often use their own security scales, which cannot be compared across brands. Independent organizations assess and rate some locks, including Sold Secure in the United Kingdom (soldsecure.com) and ART in the Netherlands (stichtingart.nl). If a lock lists such a rating, you can check it on the organization’s website. Ratings indicate resistance to the attack methods used in their assessments, not immunity to theft.
Locking technique matters
- Lock the frame to a solid, fixed object that cannot be cut, lifted over or easily removed.
- Fill as much of the lock’s space as possible to leave less room for tools.
- Keep the lock off the ground, where it is easier to attack.
- Secure wheels with a second lock or cable, or use locking skewers, especially for quick-release wheels.
- Take removable accessories such as lights and computers with you.
- Park in busy, well-lit, visible locations when possible.
Two locks are better than one
Many urban riders carry two different lock types, such as a U-lock plus a chain or cable. A thief may need different tools to defeat each one, which takes more time.
GPS trackers and registration
GPS or Bluetooth trackers can help locate a stolen bike but do not prevent theft. Record your bike’s serial number and photos, and consider registering the bike with a bike registry or your local police where available.
Who should choose which
- Urban commuter locking outside for hours: a high-security U-lock, plus a secondary lock for wheels.
- Rider who stops briefly at cafes and shops: a folding lock or compact U-lock for portability.
- Home or garage storage: a heavy chain to a ground or wall anchor.
- Low-risk, short stops: a light lock may be acceptable, understanding the risk.
Frequently asked questions
Is a U-lock better than a chain?
Neither is better everywhere. U-locks often offer more security per pound; heavy chains offer flexibility and high security but are heavy to carry.
Are cable locks enough?
Cable locks are generally easy to cut and are best used as a secondary lock.
