Locks | How to Lock your bike | Bike safety and theft | Bike Helmets
last updated 14 June 2019

15,000 bikes are reported stolen in New York City every year. Experts believe that this figure represents only 20% of the actual total.

Tools of the trade:

                       Angle Grinder   Hydraulic Bottle Jack   Frozen lock smashed
Medium size bolt cutters (shown) can cut up to 12 mm.
Large (36 and 42") bolt cutters can cut 13-15 mm.
Cordless angle grinders are now the tool of choice for professional bike thieves.
They're smaller than bolt cutters and will cut thru most anything.
A bottle jack can be used to force a U-lock open.
When cooled to -13°F with canned air spray like dust-off (actually the compressed chemical difluoroethane [152a], which replaced freon), even very tough locks become brittle enough to smash open with a hammer.
A pocket size cable cutter will cut 3/16 (5 mm) cable.

Risk Factors:

 - Expensive bike
 - In a big city or college campus
 - Leave it unattended for more than 1 hour
 - Combination locks are easier to pick
You-tube videos of thefts:
SF Police stake out| ABC news |
Locks listed in order of safety.
Type Price. Diam.1 Length2 Weight3 Pros/Cons
U or D lock $35-$100 13 mm

16-18 mm

4 x 9"

4 x 6"

2.8 - 3.2 lbs

4.5 lbs

Most come with a bracket to mount on the frame of your bike.
Kryptonite New York Standard Heavy Duty Bicycle U Lock Bike Lock $85 ( 16 mm, 4x8", 4.5 lbs)
Chain Lock $15-120 9-12 mm 21"-30" 3.9 - 7 lbs Can wrap around seat post
At 12 mm only the shortest chain lock is portable.
Kryptonite New York Fahgettaboudit 1415 Chain $130 (14 mm, 5', 15 lbs)
Folding lock $20-150 5 mm 33" 2.2 - 3.5 lbs Most compact, flexible.
About the same internal space as a U-lock but flexible.
One cut to break, as opposed to two cuts for the best D-locks and chains.
Cable lock $6-20 ¼", ⅜" (9.5 mm)
and ½" (12.7 mm) 1
Std 4- 8'


0.7-2.2 lbs Can wrap around seat post.
Where I used to live in the suburbs, there are no bike racks, so I had to tie it to a tree at the grocery store. It required 6½' cable to go around a 1 1/2' diameter tree.
20 mm Kryptonite HardWire $46 (2 3/4' 3 lbs)
1. Diameter of part that must be cut.
Cable locks are braided steel wire and the vinyl coating is included in the dimensions so the total amount of steel is less than the same size U lock.
With many U-locks you only have to cut 1 side and you can lever it open. But the the Kryptonite New York lock has a "dual bolt" design that forces a crook to cut both arms of the shackle.

2. Length - Typical lengths - Cable and Chain locks must be twice as long to wrap around their anchor.

3. Weight - Anything over 4.5 lbs is difficult to cary around.

U-lock vs Chain lock: Which is best? | The Best Bike Lock says,
If you're looking for a portable lock to secure your bike in the street every day, then you're probably best off with a U-lock. Whereas if you're only looking for a lock to protect your bike at home or at work, then the best choice is a thick, high quality chain lock.

At 5 Things Bike Lock Companies Don't Want You to Know Daniel Idzkowski recommends SkunkLock which releases noxious chemicals when thieves try to cut through your lock.

One blog post said "A person intent on stealing bikes can beat any lock in a short amount of time--no matter how much you paid for it. Make sure your bike looks like its worth less than it is, and alway park it next to a bike that's worth more and has an easier lock to pick."
Reviews at Slate 2006
Model Security
cost thickness Size†
of use
Master Lock Force 3 STD U-lock   5 $30 13 mm 2.2 10
OnGuard Bulldog STD U-lock * 10 $35 13 mm 4.5" x 9" 2.7 8.5
Kryptonite KryptoLok STD U-lock   8 $50 13 mm 4" x 9" 2.8 8
Kryptonite New York Chain With EV Disc Lock 17 $93 12, 14 mm 3'-3"" 6.1 4
Chain is 12 mm, lock is 14 mm
OnGuard Beast - chain 17 $90 14 mm 3'-7" 9.5 3.5
OnGuard Brute STD U-lock 18 $70 16 mm 4.5" x 9" 4.5 5
Kryptonite New York Fahgettaboudit - U-lock 19 $117 18 mm 4" x 8" 4.6 7
Abus Granit X Plus 540 U-lock $120 13 mm 4.25" x 9" 3.2
Note: Woven Steel cable locks got a security rating of 2

† - Dimensions are based on the size of the hole in the middle.
7" is generally long enough to go around the frame and one wheel.

‡ - The Abus Granit X Plus 540 was not rated by Slate, but is listed as the only "Solid Secure Gold" lock at The Best Bike Lock.
Abus is manufactured in Germany while Kryptonite and OnGuard are US Brands manufactured in Taiwan and China. European steel is considered better than Chinese steel. Abus has the best reputation for quality.

* When I searched for OnGuard Bulldog STD U-lock I got a lot of 11 mm versions.
The following were 13 mm.
Amazon.com: OnGuard Bulldog DT U-Lock with 4-Foot Cinch Loop Cable $41
OnGuard Bulldog STD U-Lock | REI Co-op $35

3 Major Manufactures:

At Abus vs Kryptonite vs OnGuard | The Best Bike Lock they say,
Abus easily have the best reputation for quality and reliability.
The Abus Granit X Plus 540 is the only Sold Secure Gold rated U-lock with a 13 mm shackle.

5 Best Bike Locks - May 2019 - BestReviews The Kryptonite KryptoLok Series 13 mm U-lock with 4 ft cable ($50) was rated #2 behind the Fahgettaboudit Chain.

Combination locks are easier to pick and sometimes hard to manipulate the numbers.

Abus vs Kryptonite vs OnGuard | The Best Bike Lock

ABUS locks have a great reputation and for a good reason. They offer high security with usually a higher price tag. Abus Granit X-Plus is made of a special temper hardened steel which has a high resistance against cutting and sawing. It features a dual locking system which stands out because most U-type locks only have one.
Source: The best bike locks and buying guide | eMobility Headquarters

The ABUS Granit X-Plus 540/160 - U-Lock $120 4.9 (13) 11.6" x 7" Double Locking Security level 15/15 was their top pick.
13 mm hardened square shaft parabolic shackle.

 German Abus U Mini 40 Mini Round Shackle U Lock, 5.5"/15mm Heavy Duty Compact Bike Lock : Bike U Locks : Gateway $48 4.3 (148)

How To Choose Lock | kryptonitelock.com

The best bike locks and buying guide | eMobility Headquarters

Sold Secure Gold bike locks: The List | The Best Bike Lock

A 7" long lock will wrap around the frame and 1 wheel to a fixed object and is considered the best for most situations.
Inside Dimensions - Outside dimensions are about 2" wider and 2.5" longer:

Longer Locks:
The Kryptonite Kryptolok Long Shackle U-Lock Bicycle Lock with FlexFrame-U Bracket is 11.5 " long by 4" wide.

Anti-theft Protection - Insurance
Some bike locks, now offer their own "anti-theft protection" with some of their locks. Under these schemes, if your bike is stolen as a result of your lock being broken, they will pay you the value of your bike up to a certain limit determined by the security level of the lock.

It sounds great, but in practice they impose a lot of conditions which can make it difficult to make a successful claim.

Comparing the first nine months of 2018 to the same period last year, San Francisco police say bike thefts dropped 23 percent, from 572 to 441. ()KQED News)

Smart Bluetooth Bike Lock, App Control Anti-Theft Keyless Bicycle 3'-2" 10 mm cable $37

SL Elite Fingerprint Bike Lock, Anti-Theft Keyless Bicycle Lock with USB Charge IP66 Waterproof 39.4 inch 10 mm Bicycle Cable Locks for Bike, Motorcycle, Door, Fence : Sports & Outdoors $45

Bisecu : The world's first fully automatic smart bike lock by BISECU Inc. Kickstarter
  Bluetooth auto-lock, alarm, theft notification.

SKUNKLOCK | The Deterrent Lock That Fights Back Against Thieves With Noxious Chemicals

Best GPS Bike Trackers and Smart Locks

Locking Mechanisms:
Notations like X2P refer to the locking mechanisms. The notation is most frequently used in OnGuard and Magnum locks, but applies to most.
Kryptonite's double-deadbolt is the same thing.
X2 - Locking mechanism on both end of U-lock.
X4 - Locks both sides of each end.
I don't know what the "P" stands for.

Locks at only one end allows you to make one cut and twist the lock open.
X2 locks can't be twisted to you have to make two cuts.

Helmet Locks:
You can also make your own with 15 inches of 1/8" or 3/16" cable and a 5/8" nut and a ferrule & stop set,
or use a #11 rock climbing stopper.

Bike Locks | Amazon.com
The Best Bike Lock for 2019: Reviews by Wirecutter | A New York Times Company
The best lock to protect your bike. | Slate 2006
Locks test 2016 | RideOn
The Best Bike Locks For Keeping Your Wheels Safe | Popular Mechanics Best Bike Locks for 2018 - Reviews of Bike Locks
The Best Bike Lock: Reviews | Wirecutter
The 6 Best Bike Locks in 2018 | The Best Bike Lock
The best U-lock | The Best Bike Lock
Bike U-Locks | Amazon.com
How to Choose Bike Locks | Eastern Mountain Sports
Wheel & Seat Locks | The Best Bike Lock
5 Things Bike Lock Companies Don't Want You to Know | D Idzkowski
How to stop your bike lock jamming | The Best Bike Lock
Bike thief reveals tricks of the trade in this shockingly candid interview - Cycling Weekly

See also Bike Helmets.
How to Lock your bike