The KryptoFlex 1218 is a six-foot cable combination lock made by the well-known brand Kryptonite. This lightweight (1.7 lbs) cable lock is an easy-to-use theft deterrent that allows you to lock up your entire bike, wheels and all. It costs $27.50.
The KryptoFlex cable does fit into bike jerseys, but isn't recommended for long rides due to the weighing down of the pockets.
Kryptonite gives the KryptoFlex 1218 a security rating of 2 out of 10. We managed to cut through the KryptoFlex with a pair of cheap bolt cutters in about 2 seconds. Handheld wire snips could break through in 5 seconds. We smashed the locking mechanism apart in about 20 seconds with a hammer.
One snip with the bolt cutters is all it took to cut the nice Univega touring bike free. (Don't worry, we returned it!)
These tests resulted in our security score of 2 out of 10, the lowest we tested. So keep that bike locked up within eyesight! For a boost in security with even better security, the Ottolock Cinch is a definite step up in theft prevention.
Ease of Transportation
The KryptoFlex 1218 comes with the Kryptonite's Transit FlexFrame-C transportation system, which is a mounting bracket that you install on your bike frame or seat post. The FlexFrame C is easy to install, but its materials (plastic body with a fabric webbing strap) lead one to wonder how long the bracket will hold up. We also found that larger diameter frames (some mountain bikes) were too big to install the FlexFrame-C. Most frames will work, however, and the spline (the male part of the bracket located on the lock itself) is adjustable, giving you lots of options on where to put the lock while you are riding.
The Flex Frame-C mounting bracket can be put a variety of places on the bike frame. Right below the seat post is a convenient spot.
Burlier locks like the Kryptonite New York Standard U-Lock or the ABUS Granit X-Plus 540 also have mounting brackets to carry your bike on your frame while riding. This lock is small and light enough to throw in your bag or wrap around the seat post if you want to opt out of the bracket. We also tried to fit in the back pocket of a bike jersey but found it uncomfortable on a long ride.
Ease of Use
A four-digit combo that is re-settable seals the "easy to remember" deal - no keys to misplace. The KryptoFlex is straightforward to use: dial in the combo, unlock and place around your bike, then re-lock. Compared to the Akita 8041, we liked the Akita's less twisty design when considering the extra moments of having to unwind the KryptoFlex before threading through your bike. The twists do make the KryptoFlex into a more compact lock to carry, however, and allow you to wrap it around your seat post. The Akita also won points in this category with its large combo dials that made it easier to manipulate than the KryptoFlex.
The KryptoFlex's 6' length make it easy to secure any and all parts of your bike. The locking mechanism is too big to fit through some saddle stays, but worked on others.
Kryptonite's instructions were to remove your front tire and then lock up both wheels and frame in a bike sandwich of sorts, but we found that the 6-foot cable was long enough to fit around the frame and wheels without issue. We first thought that removing the front wheel was an unnecessary hassle, but then tried to determine if this position was more theft-resistant. After pondering this question for cable, chain, and U-Locks, we concluded that both positions offer little security when using a cable lock.
A bike with its front tire removed and locked with the rear tire and frame, as per Kryptonite KryptoFlex 1218 Cable Lock instructions.
This lock is excellent for throwing in your bike basket while running errands in a small town. While the KryptoFlex doesn't have the security rating for an overnight in New York City, it's suitable for securing your bike during the daytime when you know you will always be within eyesight. Locks like the Kryptonite New York Fahgettaboudit U-Lock Mini and our Editors' Choice, the New York Standard scored much higher in our security tests and more secure for leaving your bike out overnight.
Our testers noted that lightweight combo locks like the KryptoFlex are useful for bike touring since the bike will always be nearby. One experienced bike tourer told us that she often locked her bike to itself and had it close if not in her tent, making certain this vital piece of equipment would not be stolen during the night. Other tourers headed through cities opt to carry the heavier U-locks to ensure security. This lock can also be used while traveling to lock up luggage or rented equipment (like cross country skies to your unsecured roof rack) in a pinch.
Wrap the cable around your frame for a quick errand. The KryptoFlex holds its shape well and can also be twisted around the seat post or handlebars.
Priced at $27.50 and easy to find online or at a variety of retail shops, the KryptoFlex is a reasonable buy for those of us not needing a fortress of security (that also add five pounds of extra steel!) around our bikes. OnGuard's Akita 8041 runs a bit less and has some notable differences in usability and weight. However, both of these locks earned the lowest scores in security, so if you're looking for real peace of mind when locking up your bike, invest in a more secure deterrent. Our Best Buy award winner, the Kryptonite Series 2 Standard U-lock is $23 more but earned a 7 out of 10 in our security metric. Kryptonite sells all of their locks with lifetime warranties, but you won't find Kryptonite or any lock manufacturer willing to offer theft protection on cable locks.
Ben showing us how he broke the KryptoFlex lock with a hammer. It took less than a minute.
The KryptoFlex 1218 is an easy to use and easy to transport combination cable lock in a style that works well for people that live in rural areas or are locking their bike up for a hot second while training. We don't recommend this lock or any cable lock for those living in a city.