
The Kryptonite New York Fahgettaboudit is the gold standard of U-lock security. The 18mm hardened steel shackle resists bolt cutters, angle grinders, and hammers. Sold Secure Gold and ART4 ratings mean it's certified against professional theft attempts. For high-value bikes in urban environments, this is the lock. The weight is the trade-off for maximum security.

The Kryptonite Evolution Mini-7 is the best everyday U-lock. Sold Secure Gold rating means it's certified against standard theft tools, the double deadbolt locking engages both sides of the shackle, and at 2.4 lbs it's portable enough to carry on rides. The right lock for most urban cyclists who ride quality bikes.

The Abus Bordo 6000 is the best folding lock available. The 5mm hardened steel bars resist cutting, the folding design stores compactly in the included frame mount, and Abus's quality construction makes the joint mechanism reliable under repeated use. The pick for cyclists who want a lock that doesn't protrude from their frame.

Chain locks are more flexible than U-locks — they work around posts, railings, and trees that U-locks can't reach. The Hiplok Gold's 10mm hex link chain resists cutting tools, and the design lets you wear it around your waist on rides without a bag. The right lock for cyclists who park at non-standard fixtures.

A cable lock is a secondary deterrent, not primary security. Use it in combination with a U-lock or chain to secure your wheels and saddle to your frame. A cable lock alone is defeated with wire cutters in seconds. Used correctly — as a supplement to a quality U-lock — cable locks prevent wheel theft and component theft at minimal cost.
Sold Secure (Bronze/Silver/Gold/Diamond) and ART ratings are the most reliable independent security certifications. Sold Secure Gold means the lock was tested against professional tools including angle grinders for defined time periods. Avoid locks with no independent security rating — manufacturer security claims are unverified marketing.
U-locks are the most secure for their weight. Chain locks are more flexible but heavier for equivalent security. Folding locks are the most packable but have more joints that can be targeted. For maximum security: U-lock for the frame and rear wheel, cable for the front wheel. For on-the-go flexibility: chain lock that wraps around the post in situations where a U-lock won't fit.
Lock the frame AND rear wheel through the U-lock shackle. The rear wheel is the most expensive to replace. Front wheel goes through a secondary cable or second lock. Lock to a fixed immovable object — not a sign post that can be lifted off, not a wooden fence that can be cut. Lock tight with minimal slack — a loose lock gives thieves space to work tools.
The Kryptonite New York Fahgettaboudit is the most secure portable U-lock available — 18mm hardened steel, Sold Secure Gold, ART4 rated. For ultimate security, pair it with a chain lock through the front wheel. Nothing is impenetrable given enough time and tools, but a Fahgettaboudit requires an angle grinder and significant time — most thieves move on.
Quality folding locks (Abus Bordo 6000, Hiplok Fold) are rated Sold Secure Silver — adequate for most situations. They're less secure than equivalent U-locks because the joints are a potential weak point. For high-value bikes in high-theft areas, use a U-lock as your primary lock and add a folding lock as a secondary.
See also: Best Bike Helmets • Best Bike Lights • E-Bikes & Powersports Hub