Joshua Tulberg November 30, 2017 05:42 PM Anyone who would buy this is already someone who is aware of the issue. And if you are aware of the issue then there is no point in buying it. Just do the "Dutch Reach" and open the car door with your right hand, forcing you to look over your shoulder for a bike. martinkopplow December 1, 2017 08:07 AM Joshua is right. Also, if a cyclist has no Bluetooth enabled, he's already as good as dead, because car drivers will soon learn to rely upon the device and carelessly open the door whenever it issues no warning. This device is bound to do more harm than good. If your car has a wing mirror to mount it onto, then just use the mirror. MartinVoelker December 1, 2017 08:08 AM This addressed a grave problem. The issue even has a name - dooring - and a wiki page where we learn that a study in Chicago found that doorings made up 19.7% of all reported bike crashes. Built-in safety features in cars probably won't be able to handle the situation as they don't work once the engine is shut down. Rusty Harris December 1, 2017 10:17 AM Don't lane split, and follow the traffic laws. Problem solved. Martin Winlow December 1, 2017 11:07 AM I'm also with Joshua on this one. If you have to look *at* your mirror for this system to work, why not save your money and look 'into' the mirror to see if anything is coming (including pedestrians and vehicles - blind spots permitting). Isn't failing to do so and causing problems by 'opening a door to the danger...' an offence everywhere else in the world, like it is in the UK?A better target for Mr Wng's time and skills would be a similar device for detecting *on-coming* traffic (especially vulnerable traffic such as pedestrians and horses) in single track country lanes with very high banks/hedges such as exist all over the more remote parts of the UK. MerlinGuy December 1, 2017 11:58 AM Another stupid Answer in search of a problem. We're all down with Josh on this one. Seriously, if you're already looking at your mirror then you see the cyclist coming. Ed Llorca December 1, 2017 01:27 PM The bit you all missed is that the driver is not looking at the mirror already. the flashing red led will allegedly get their attention. That is how it works. the problem I see is that with the short range of bluetooth and the speed of a moving bike, by the time the light turns on the cyclist is already there. Don Duncan December 1, 2017 03:32 PM Cars will come with a built-in warning, a motion sensor that is part of the already lane-change warning system. JeffK December 2, 2017 01:02 AM While I certainly don't want to harm a bicyclist, I have even less desire to have my door (and possibly my arm) removed by a passing motorist. It behooves anyone exiting a vehicle on the street side, whether driver or passenger, to ensure the coast is clear. Several decades ago, the front seat passenger in a car parked on the left side of our one way Main Street shoved open the door into the path of a firetruck responding to a call. Fortunately, it was an elderly lady who used her cane to open the door and the only damage was to the vehicle. That said, as a bicyclist in my pre-arthritis days, I see no reason to ride so close to parked cars as to be in the arc of an opening door. DavidStonier-Gibson December 2, 2017 10:02 AM Dumb idea of the month!