Keeper 510 Folding Lock 100cm x 3mm

The Kryptonite Keeper 510 is a folding bike lock made from 3 mm hardened steel links that open out to 100 cm. Kryptonite rates it 5 out of 10 for security and it holds a Sold Secure Bicycle Bronze rating, for moderate-security lock-ups. It weighs 862 g and comes with a frame-mounted transport bracket and two keys.

How secure it actually is

On Kryptonite's own security scale the Keeper 510 scores 5 out of 10, and it carries a Sold Secure Bicycle Bronze rating. Kryptonite builds it for moderate-security lock-ups: the café stop on a Sunday ride, a bike parked at the trailhead while you walk, or a commuter bike outside the office in a busy street. Lock it somewhere well lit and busy, to something solid that cannot be cut or lifted over, and keep the fit tight and off the ground.

Weight against security

A lock you leave at home secures nothing. At 862 g, the Keeper 510 folds up and rides strapped into its transport bracket on the frame, so it can come on every ride without filling a pocket or a bag. That makes it an easy lock to carry every day.

What it locks to

Unfolded, the links give you 100 cm of reach. Kryptonite's recommended lock-up captures an anchored stationary object, the bike frame and the rear wheel, so check that 100 cm goes around your usual rack or post.

Keys and mounting

Two keys come in the box. Register the key number with Kryptonite's Key Safe program and replacement keys are available if you lose both. The transport bracket screws onto your frame's braze-on mounts with the screws and washers supplied (Kryptonite's recommended method), or straps to the frame or seat tube with the plastic mounting straps if you would rather keep the mounts free. Check that the lock clears your pedals, steering and brake and gear cables before you ride.

Looking after it

Give the lock cylinder a few drops of silicone, graphite or Teflon-based lubricant several times a year. Avoid standard WD-40, which strips lubricant out rather than adding it.