Bike security is an important issue for me because I leave my bike in a public parking area every day and also lock my bike up when running errands around town. I have used varied locks and measures over the years, including -
I have yet to encounter a stand alone locking product that makes me feel comfortable leaving my bike out for a long period of time. I guess the closest stand alone product in my view would be a U-lock that also comes with a cable. And I guess I should note that when I say "stand alone," I mean a lock that can secure both wheels and the frame, without having to remove a wheel to either lock up or take with you.
Personally, I prefer not to have to remove a wheel to lock my bike - mainly because I lock my bike up multiple times a day. If I just want to leave my bike out for a short period of time in an area with heavy pedestrian traffic, I might just use a "stand alone" lock. However, if I am going to leave my bike unattended for a long period of time I usually use a combination of products.
The reality is that if a thief really wants your bike, s/he is going to be able to defeat any attempt to lock it up. One benefit of using multiple locks is that it is likely to slow the thief down. When the folks behind a new lock contacted me for a review of a new bike security product, I was happy to accept. The lock is called the Foldylock, and surprise, it's a folding lock. Here's the spec sheet from the product page -
And here is the lock in all its folded out glory, the storage bracket is what is in the middle.
The lock is perfectly capable of securing the frame and a wheel to a stationary object, as seen here when I used it to secure my bike to a bike rack.
And in terms of size perspective, it's not much bigger than a standard water bottle cage when folded up.
One issue with locks is having to carry them, and the Foldylock comes with a bracket that can be attached to a frame via straps or by Allen bolts. The straps are a great option if you have more than one bike because you can quickly take the bracket off and put it on another bike. I attached the bracket to my frame and the lock comes with special Allen bolts that are a bit longer than standard bolts, and with a longer Allen wrench. The longer Allen wrench is key, because as you can see, the Allen wrenches on my standard multi-tool are not long enough to extend through the bracket to secure it to the frame.
The last thing I would ever think of when buying a lock is what color it is, but the Foldylock is advertised in different colorways. Interestingly enough, the green option that I received does not appear on the Kickstarter page lineup.
I will note that all of the links are covered by plastic to keep the lock from scratching the frame or other parts of a bike.
I have only been using the lock for a short time now, however I would describe it as "sturdy" and easy to use. On the Foldylock page there is a video of attempts to break the lock with all manner of tools and methods. Of course none work or they would not have put the video on their webpage. They also claim the lock is rustproof, which I would not be able to comment upon until using it for an extended period of time.
This is still not what I would call a "stand alone" lock. I have been using it in combination with a Kryptonite cable to secure my rear tire, which has a quick release skewer. Still, it is a nice lock that provides a bit more flexibility in terms of size than a standard U-lock. The makers have met their funding goal and it appears the product is scheduled to be ready for distribution in April of 2017 with a price of $65, which is in the range of what most would likely consider to be "higher end" bike locks.
I do wonder how many links it would take to make such a lock an attempt at a stand alone solution, meaning that the lock was long enough to secure both wheels, without removing one. Who knows, maybe a Foldylock Max will appear in the future.