U-Lock vs. Chain Lock: Which Should You Use for Your Bike?

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Did you know that a bike is stolen every 30 seconds? That’s more than 2 million missing bicycles a year!

According to Garage 529, the world’s largest bicycle registry, bicycle theft costs North American communities more than a billion dollars each year.

Bicycle secured with u-lock and chain lock

The type of lock you use to secure your bicycle can mean the difference between hopping on your ride and filing a police report. You don’t want to add to the alarming statistics above, after all. In this post, we’ll explain the differences between two standard methods of locking up your bike securely: U-lock vs. chain lock. We’ll lay out the pros and cons of these kinds of locks and help you figure out which is the best option for your needs.

The Importance of Sold Secure for Security Standards

The Master Locksmiths Association bestows the Sold Secure rating on locks that professionals have independently tested for security standards.

Sold Secure classifies bicycle locks as diamond, gold, silver, or bronze. Each category reflects the time and number of tools used to ‘break’ a lock. The higher the security rating awarded by Sold Secure, the greater the security provided by the lock.

In our opinion, any lock less than bronze level is vulnerable to prying, hammer strikes, a bolt cutter, a hacksaw, or other types of tools used by an experienced thief. If financially feasible, we advise that you buy a gold-level lock for strong bike security.

U-Lock vs Chain Lock

The main differences between a U-lock and a chain lock are the level of bike protection, portability, weight difference, versatility, resistance to basic tools and complex tools, and overall value in terms of theft deterrence.

All About U-Locks

U-locks, also known as D-locks, are brutal shackle locks. U-locks are horseshoe-shaped locks that come in multiple sizes (the best is 13 mm to 16 mm) and are usually vinyl-coated steel. The goal is to choose a D-lock that fits securely around the items you’re locking with the smallest gap possible.

Small-to-medium-sized U-locks generally secure one wheel of your bicycle and your bike frame to a stationary object, such as a bike rack. Larger models secure both your bike wheels and the bike frame to a fixed object.

This heavy-duty bike lock is resistant to chisels, hammers, and theft from bolt cutters. The horseshoe shape, if properly fitted, will limit the amount of leverage that a bike thief can obtain with a crowbar or similar types of tools.

U-locks are lightweight and affordable compared to chain locks with similar security ratings.

Riding with a U-lock requires either a bike-mounted carrying attachment or space in your backpack.

The Abus Granit is an example of a highly rated U-lock:

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05/17/2024 11:59 am GMT
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05/17/2024 11:59 am GMT

Pros and Cons of U-Locks


  • Very durable
  • Excellent visual obstacle for added level of protection
  • Can come with an optional cable
  • Affordable
  • Resistant to multiple tool attacks from a bike thief
  • Available at all Sold Secure levels


  • Can be difficult to fit through some bike frames
  • Can be awkward to carry and typically requires a carrying attachment on your bike
  • Smaller locks can be difficult to loop around larger stands or non-standard objects

All About Chain Locks

Chain locks for bicycles are made of hardened links of steel, typically covered by a protective sleeve of nylon or plastic.

The locking mechanism can be permanently attached to the chain or a separate padlock.

Chain locks come in multiple strengths, weights, and sizes (9 mm to 16 mm) and can be stationary or portable.

Bike secured with chain lock
Watch out for those exposed links on a chain lock. They can damage your bike’s paint!

Heavy chain locks generally offer a higher level of security due to their construction. Most portable chain locks are at least 23 inches long, allowing for multiple locking options, unlike U-locks. The most brutal chain locks are usually the heaviest, even in the mobile category. If you go with a chain lock for bike security, we recommend you select a larger sized link (15 mm or 16 mm).

A quality chain lock is usually heavier than a U-lock and can be a bit cumbersome to carry around. Some versions can be attached to your body or carried in a knapsack.

It’s never a good idea to wrap a chain lock around your bike frame, unless you’re a fan of damaging your own property.

The OKG Lock Chain is an example of a highly rated chain lock:

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05/18/2024 04:38 am GMT
We earn a commission if you make a purchase, at no additional cost to you. As an Amazon Associate we earn a small free from qualifying purchases.
05/18/2024 04:38 am GMT

Pros and Cons of Chain Locks


  • Tough as nails
  • Longer length allows for more locking possibilities
  • Available at all Sold Secure levels


  • Heavy and bulky
  • Locks have to be appropriately attached and fitted to thwart tool attacks
  • Exposed links on the chain locks can damage your bike’s paint

Final Thoughts: Which Bike Lock Is Best for You?

Now that you’re up to speed on the difference between a U-lock vs chain lock, it’s time to choose one for your bike.

There are a few things you must consider when choosing the best method for locking up your bike, including the risk of theft in your area, your price range, and how portable you need your security method to be.

Whichever bike lock you choose to go with, make sure you use it properly, secure it tightly, and carry it with you always to prevent against bike thefts.

If you’re unable to afford a bike lock at the moment, here are some ways you can secure your bike without a lock.