Küat's cleverly designed Bottle Lock sounds like an ultra-handy way to tote a cable lock on your everyday commuter and in many ways, it is. Unfortunately, it's not as secure as it's made out to be and a basic dimensional error makes for a noisy ride around the block, too.
The idea is brilliant: tuck a winding cable reel into a housing that's the same size and shape as a standard water bottle, and integrate the lock mechanism up top. Right away, the issue of how to carry a cable lock essentially disappears, given the multitude of bottle cages available, and there's even a little compartment on the bottom to store the keys so – in theory – you always have them on hand when needed.
Using the Bottle Lock is pretty simple. Just pull the cable out of the spool, run it around the appropriate bike parts and a secure anchor, then plug the steel cable end into the receptacle at the top of the housing and go about your business. When you're done, release the cable end with the top-mounted brass lock cylinder then rotate the top to wind the cable back into the body.
Video: Kuat Bottle Lock
Adding to the convenience is the 5ft of cable – long enough to run through the frame and both wheels – and you don't need the key to lock the Bottle Lock, either. We didn't bother to use the lower compartment, however. Items joggle around too much down there while you're riding (more on this later) and it was easier to just leave the key inserted into the keyhole.
Security is less than confidence inspiring, though. Küat advertise the Bottle Lock as having an 8mm-thick cable but even the clear plastic jacketing only measures 7mm across and the braided steel cable itself is closer to 4mm. It's still good enough for quick stops where bike theft isn't rampant but the skinny cable is no match for a good set of bolt cutters so we'd recommend you limit use of the Bottle Lock to low-security excursions only.
More irritating is the plastic housing. It feels cheap in your hands – like it might break if you were to drop it on the sidewalk on a cold day – and it's also the wrong size. Standard water bottles measure about 73mm in diameter but the Bottle Lock is closer to 70mm so it rattles incessantly unless you have a metal cage that you can bend to fit. This then makes for a tighter-than-desired hold on actual water bottles.