What a great idea! An even better one would be including a wheel-mounted charger, so that riding the bike would recharge the device.

Actually, most U-locks are physically sturdy but use cheap POS locks. There are exceptions but you pay dearly for them. They also weigh about 5 pounds.

I suspect that people would very quickly get tired of the false alarms and just ignore the alarm, unless Siegel is somehow smarter than all the engineers at the companies that make annoying car alarms. Sometimes, I wish there really was a thief just so the stupid car would be stolen and I wouldn't have to hear the alarm anymore.

That's just what all the inner cities of the world need… lots more noise! Can you imagine what would happen in China if this took off? It's a bloody silly idea. Realistically, where are you never going to be able to find something to lock your bike too? The middle of a desert and in the middle of the sea. Neither should prove too serious an issue. MW

It could never suffice on its own. It would have to be in addition to a bike lock. Otherwise the thief could just quickly ride off to a less conspicuous place and smack at the lock with a heavy object.
The more expensive the bike, the better the lock should be. I ride a so-so bike for errands around town, and my good bike is used for exercising and rarely gets left/locked anywhere. I'm speaking as someone who's had a number of bikes stolen (in a big city).
Always park the bike in a visible area, and use a good quality Ulock that can lock the frame AND a wheel to something immovable.

It will suffer from the same problem all bike alarms suffer from, its on 24-7 and it eats batteries. When the battery goes dead its useless and when its inside charging, its not protecting anything. The fact that it has to go inside to charge presents the other problem all bike alarms suffer from, if its easy to remove its useless. If its easy to get to the power source it will be disabled. And then the third problem with all alarms, bike or otherwise, if it is easy to trigger and goes off a lot, people will not only ignore it, they will be mad at you for subjecting them to this annoyance.

I think this device/idea has a lot of potential. More than just a bicycle theft deterrent, it could be attached to any sporting goods item or personal property that might have cause to up and walk away: small boat, canoe, lawn mower, large construction tools, camping gear, camera tripod, equipment bag, etc. Of course, the owner of the property should take as strong a method as is practical to prevent theft. Nothing will stop most thieves who are determined. This device adds a first level deterrent. I would buy several today.

it says low-cost Well how much $ and where?

silly it has to be recharged every few days? if seat has a quick release you could just remove and ditch the alarming seat
why not just invest in a good lock?
where is there ''not anywhere to lock your bike'' ? which is also so theft prone that you need this thing and un-isolated so someone would notice the alarm and where anyone would care..?
what protects the bike while the dumb alarm is charging?
wle

I like the idea......BUT.......
I'd want to know if anything has happened such as the alarm going off. These days with the internet of things, there must be freely accessible development tool to help this. The way I would envisage this would be:
1) RFID activated 2) Motion detector detects movement 3) Siren kicks out its dB's. 4) Alarm connects to local free or approved WiFi and sends a notification to my phone or network where I can pick it up through tweets, emails, texts etc. 5) I know that the alarm triggered at what time, and/or I can go and check if it is still there.
Services such as IfThisThenThat can help connect this very easily, all the alarm has to do is have an output to the net.