Bikes are beautiful, elegant machines, which explains why they're often the target of theft. You have to protect your bike, but doing so usually means hauling around a lock that's basically an intimidatingly giant piece of steel in various shapes. The TiGr, currently a prototype on Kickstarter, is just as sleek and pretty as a well-made bike--and hopefully does its job as well.
Created by John Loughlin and tested by Joshua A.C. Newman (of no apparent relation to power pop god A.C. Newman), the TiGr is a long, flexible titanium bow with a steel lock, either 0.75 inches or 1.25 inches wide and long enough to lock both your wheels to a stationary object. You wrap it around the top tube of the bike to store it, where it balances properly and doesn't take up any extra room. It weighs, according to its creators, about a third the weight of a typical U-lock, but is just as effective. Apparently the lock is flexible enough to wrap around objects as big as 5.5-inches in diameter--plenty big enough for bike racks, fences, street signs, and parking meters, though not as flexible as a chain. Of course, a chain also weighs a ton and must be draped around your waist, which is aesthetically questionable.
The actual security bonafides are a major reason to fund the TiGr on Kickstarter--the creators say it holds up to a 48-inch bolt cutter attack as well as a saw, but admit that these are their own tests. Part of the Kickstarter money would be used to get the lock properly accredited. They've already got $13,000 worth of pledges towards their $37,500 goal--hopefully they can get there and we can try out a very pretty-looking lock before winter comes.
What's needed are retractable bike cables (which operate similarly to a retractable doggie leash) that have a built-in alarm that sounds if someone cuts the cable to try and steal the bike.
These could be bolted onto the main frame (and probably hold a water bottle rack to make it do double duty) and weigh under around 3 to 4 lbs and include a tiny piercing siren with 9 volt battery operation in the event the cable is cut (hardened but of course any cable can be cut).
When the bike owner pulls up to a post or bike rack, they simply pull on the end of the cable, run it through the wheels and the rack and back to the box. They shouldn't even have to get a key out as it should be a 'click in place' lock and once clicked into place the alarm is armed.
To remove the bike the owner turns the key to unlock the cable end and the alarm is disarmed. Then they simply release the cable (gently) and allow it to retract again and they are on their way.
Why should this be so hard to design and implement?
Not sure if you have ever been to a city gizmowiz, but sirens are largely ineffective and mostly ignored.
Car alarms go off for hours at a time. It happens so often that most people just try to ignore the sound.