Professor Neil Barron wants to change all that, and is up on Kickstarter with the Litelock, which he claims is "the worlds first light, flexible & super secure bike lock." It is a flat and flexible lock made from a combination of materials and weighs in at a kilo, or 2.2 pounds.
All bicycles weigh fifty pounds. A thirty-pound bicycle needs a twenty-pound lock. A forty-pound bicycle needs a ten-pound lock. A fifty-pound bicycle doesn't need a lock at all.
By harnessing the unique security properties of multiple innovative lightweight materials we created a composite strap called Boaflexicore®. Each layer provides additional security, meaning it can withstand sustained attack from tools like cable cutters, bolt croppers and hacksaws.
No lock is unbreakable, and even this one only claims that " in-house testing has proven that it takes well over five minutes to cut or break the strap and lock." But that is enough to deter both the amateur and the professional who will go after easier marks.
However, to make the lock even more secure, they offer an option where you can put two of them together so that you can double-lock in parallel or put them in series if you have a big tree or pole that you want to lock to.
Rule Number two about bike locks is that the price is directly proportional to the lock's effectiveness, and that holds true here, with a price tag of 70 pounds, US$ 104 today. However that is less than I recently paid for a little ABUS D-lock. I want one. More on Kickstarter