When top security and locking flexibility are of prime concern, hardened steel chain locks are hard to beat. Not always the easiest or most convenient to carry, purpose built security chains remain a reasonable choice for people in high-theft areas or those forced by circumstance to lock their fancy bikes in vulnerable places. Common sense prevails—no lock is immune to power tools or all out attack—but if these locks aren’t enough to prevent bike theft you should look into at least a beater lock-up bike or perhaps a new neighborhood altogether.

ABUS
The Brooklyn Chain

Price: $100

Length: 47” (120 cm)

Link Diameter: 10 mm, square

Weight: 2.8 kg

Keys: Single-sided conventional key, two included

Features: Loop chain allows slipknot-like locking, titanium-body padlock, fabric chain sleeve.

The Brooklyn Chain from ABUS is their answer for people locking in one of the most theft-prone places in the country. The square, 10 mm chain links make it resistant to bolt cutters (the padlock features a 10 mm round shackle), the end-link loop makes it easy to lock, just put the end link through the loop and clasp the shackle. Given the slipknot style locking and long chain length, you have to pay particular attention that the chain can’t be manipulated over the top of a parking meter or street sign. That said, the same long chain allows you to catch both wheels, the frame, and a solid object in the same loop for maximum theft deterrence. The fabric cover helps to prevent frame damage from the chain links but prevents easy wearing around the waist unless you’re the perfect fit for the chain length, approximately a 36 - 38” waist.
www.abus.com

Kryptonite
Evolution Series 4 1090 Chain

Price: $80

Length: 35.5” (90 cm)

Link Diameter: 10 mm, hexagonal

Weight: 2.6 kg

Keys: Flat key, three included, one lighted

Features: End link deadbolt locking design, disc-style lock cylinder, fabric chain sleeve.

The Kryptonite Evolution Series 4 1090 Chain is unique in that it doesn’t use a padlock to secure the chain, but a lock integrated into the end with a hardened and protected deadbolt engaging the last chain link. The integrated lock with a cylindrical cylinder flat key complicates cutting and picking attacks, forcing thieves to go for the hardened steel, hexagonal links. The non-adjustable 90 cm length isn’t enough to wrap around all but the thinnest people’s waists, leaving you to stow the lock in a backpack or the optional cargo bag, and the same short length prevents locking both wheels and frame with the chain. The lock mechanism itself does not allow you to remove the key unless the deadbolt is engaged, preventing the rare but real unlocked lock-up. Check out the shorter integrated chain locks from Kryptonite if the 1090 chain is more than you need.
www.kryptonitelock.com