Here are some "smart" tail lights I found on Amazon:

G Keni Smart Bike Tail Light, Brake Sensing Rear Lights, Ultra Bright LED Warning Bicycle Flashlight, USB Rechargeable, Auto On/Off Sensor, IPX6 Waterproof, Cycling Safety Back Taillight Accessories Onvian Smart Bike Tail Light, USB Rechargeable Ultra Bright IPX6 Waterproof Brake Sensing Bicycle Rear Lights, Light Sense Rear Accessories Fits Any Road Bikes EBUYFIRE Smart Bike Tail Light, USB Rechargeable,Intelligent Light Perception Bike Rear Light,4 Modes Ultra Bright Auto On/Off,IP65 Waterproof,Easy to Install for Any Bikes Padonow Smart Bike Tail Light: Auto On/Off Flashing Lights Red Back Led Warning Flashlight Easy Mount Cycling Safety Warning Taillight USB Rechargeable Ultra Bright Light Sensing Bicycle Rear Light JIRVYUK Tail Light for Bike, Brake Sensing Rear Lights, Ultra Bright LED Warning Bicycle Flashlight, USB Rechargeable, Auto On/Off Sensor, IPX5 Waterproof, LED Bicycle Tail Light for Any Road Bikes

Having the same looks, prices, description grammar, no-name random "brand" names and sometimes even stock photos and videos, these seem like each-other's knock-offs coming from the same factory.

While I absolutely love the brake detection idea, should trust these with the technology and execution?

Or is there a bigger brand that introduced this idea that I should go for instead?

  • 1
    What is brake detection and what do you expect it to do ? How many rear lights do you plan on using? And how often do you ride in a group or with other riders ? I'd doubt this has any use for road users except other cyclists.
    – Criggie
    Oct 8, 2020 at 7:24
  • 1
    Its $20 so not a big cost - just get one and try it. Run a second rear light of a different design as well - if one goes flat, fails, or falls off you probably won't notice.
    – Criggie
    Oct 8, 2020 at 11:19
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    If $20 is a problem and you don't have some kind of monopoly agreement with Amazon, why not order directly from Aliexpress?
    – ojs
    Oct 8, 2020 at 16:56
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    I doubt the brake lights would be useful on a bicycle. Traffic signals work because most road users are essentially programmed to watch out for and respond to them, but nobody is watching out for braking (or turning) indicator lights on a bicycle. Maybe, just maybe if stuff like this becomes insanely popular in the future, things will be different.
    – Wsal
    Oct 8, 2020 at 19:12
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    On viewing your video, this product is really only of use in a group of cyclists. If there's a car close enough behind you that brake warning makes a difference, then the car is far far too close. It feels like a product looking for some kind of differentiation from the myriad of other lights out there.
    – Criggie
    Oct 12, 2020 at 7:37

1 Answer 1


The brake detection is based on an accelerometer, and is not a complicated feature. I have had a similar feature on a Chinese front light and it worked ok from what I can see. So that's probably not a key reason to buy a branded light instead.

Amazon are often parasitical in these products - AliExpress charges $11 for a similar (same?) thing https://www.aliexpress.com/item/4000239342283.html

Cheap lights, especially tail lights can post a risk of death, in that I have purchased cheap lights from Amazon (albeit originally from China, similar to this), and they went out with no warning (battery dead) on a high-speed road. (Though apparently some or all of the lights you link to have a battery indicator feature)

The biggest problem with these lights tends to be:

  • small battery
  • excessive brightness draining said battery
  • lack of proper voltage-sensing battery indicator (about to die in 10 seconds is not good enough)

As a second light it would be ok, but I would not rely on it alone.

If you want a better product then a brand might well be better in several ways.

For example:

The best quality light like you mention (and possibly the first) is made by Lupine:


The Rotlicht Max is 1680 mAh battery, the Rotlicht is 830 maAh

The AliX light is 420 mAh, the Cateye Sync is 500mAh and the cheaper model will be even less, and the Strip Drive Pro is 800 mAh.

Exposure are a similar quality brand to Lupine, and they have a 1500 mAh light


and a 700 mAh light


The Exposure & Lupine products are clearly much better than the AliX one, but they cost 10x as much, so they should be.

By paying for a brand you might get better build quality, better attachment mechanism, weather sealing , packaging, marketing, larger battery, better documentation, support videos, warranty and so on.

I don't think you could go too far wrong by buying one direct from China and then if it turns out to be inadequate then upgrading to a quality brand later. Or you could just go straight to quality now.

  • 3
    I've also had a Cateye (not cheap) rear light that went out going over bumps on skinny tyres, so it's not just the cheap ones that are risky. If you can't twist round enough to check, 2 rear lights is the way to go
    – Chris H
    Oct 8, 2020 at 19:05
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    Your points are fine and valid, but this is veering off into product rec which tend to expire quickly.
    – Criggie
    Oct 8, 2020 at 19:08
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    Rated battery capacity is only part of the story - I've had a name-brand computer last for years on a single coin cell. A similar chinese one lasted two weeks on a pair of AAA. So power draw is also a factor in life.
    – Criggie
    Oct 8, 2020 at 19:09
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    also it's not uncommon for one Chinese seller to say '400 mAh' and another to say '600 mAh', when in fact both are exactly the same internally; best to assume two identical-looking products are identical
    – thelawnet
    Oct 8, 2020 at 20:25
  • 1
    -1 - Does not answer the question, which is about the reliability of the smart brake detection, not the reliability of the light.
    – mattnz
    Oct 8, 2020 at 20:55

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