The two most-recommended U-locks for city bikes. Both carry top-tier security ratings — the difference is hardened-steel shackle size, keyway design, and how they mount to the frame.
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| Aspect | Evolution Series 4 Standard | ABUS Granit X-Plus 540 | Winner |
|---|---|---|---|
| Security rating | Sold Secure Gold | Sold Secure Diamond / Level 15 | X-Plus 540 |
| Shackle diameter | 14 mm hardened steel | 13 mm Abus PowerCell | Tie |
| Shackle bolting | Double-bolted | Double-bolted (Abus Plus) | Tie |
| Cylinder | Kryptonite disc-style | Abus X-Plus disc-detainer | X-Plus 540 |
| Weight | ~1.9 kg | ~1.6 kg | X-Plus 540 |
| Frame mount included | Yes (FlexFrame-U) | Yes (EaZy KF) | Tie |
| Anti-theft guarantee | Yes (US/Canada) | Limited | 4 Standard |
| Street price | ~$80 | ~$130 | 4 Standard |
Pick the Kryptonite Evolution if you want the best-known keyway, free Anti-Theft Protection Offer, and broad replacement-key network in the US. Pick the Abus Granit X-Plus 540 if you live somewhere bike theft is endemic — the X-Plus disc-detainer cylinder and double-bolted shackle lift it to Sold Secure Diamond / Abus Security Level 15, a full tier above most U-locks.
Kryptonite Evolution — Sold Secure Gold at ~$80 with the industry's best replacement-key service.
Abus Granit X-Plus 540 — higher security rating, X-Plus disc-detainer cylinder resists picking + drilling.
Our sizing guides and category pages help you narrow the field.