Lezyne Saddle Ai Alert 250 Rear Light

The Lezyne Saddle AI Alert 250 Rear Light is not only extremely bright but it also comes with brake-sensing technology to alert other road users that you're slowing down. The bracket mounts securely to the rails of your saddle, it's easy to use and the mount also doubles as a waterproof charging port cover. Both the light and bracket are made from beautifully CNC machined aluminium and the light is a joy to use – though it doesn't come cheap.

Looking for more options? Check out our best rear bike lights buyer's guide.

As you've probably guessed, the light itself doesn't use artificial intelligence. The AI part of its name refers to the machine learning Lezyne used to develop the software that takes input from the light's accelerometer and decides whether to turn on its super-bright brake light.

Lezyne gathered over 1,000 hours of riding data, and fed it into the AI model. This data included speed via GPS, G-forces from an accelerometer and info from braking achieved by attaching a custom switch to a brake lever. Lezyne says the AI model was used primarily to filter out false positives, such as G-force events resulting from speed bumps.

The result is that the light does get considerably brighter when it detects you're braking, showing other road users you're slowing down. This could be a driver or your mate riding behind you, and my experience suggests it works.

This does rely on those following you understanding that the light is brighter because you're braking – and their willingness to act on that information. The light itself can't control those elements, of course, but it does provide the information, and it does that well.

Attaching the light

The light and the mount are both beautifully made from CNC-machined aluminium.

The bracket is designed to attach to standard saddle rails, including 7mm diameter and 7x9mm carbon rails, using a T25 tool. A hex key would have been a more common choice, though I guess the T25 will offer a little more security.

Either way, it's easy to attach and secure, and with the light mounted parallel to the ground it offers great visibility to other road users, with Lezyne saying it's visible through a 270-degree range.

There are a few downsides to the location of the mount: some more exotic saddles are out of the question and most saddle bags will be incompatible too.

The bracket doubles as a threaded waterproof cap for the back of the light that houses the charging port. That IPX7 rating is as good as it gets too, meaning it can survive being submerged in water.

Mounting and taking the light off the bracket is easy, even when you're wearing winter gloves. It's similar to a Garmin-style quarter-turn mount, attaching without any hint of play.

Operation

The multi-function button is on the front, in the centre of a ring of LEDs. You hold it down for two seconds to turn it on and off, and a normal push will let you cycle through the seven modes.

Pressing the button while the light is off provides the battery status, an LED on the side showing green for 100-75% charge, amber for 75-25% and red for 25-0%.

You can switch on the AI Alert – the brake-sensing mode – by holding the button down for five seconds when the light's off, until the sidelight blinks. It blinks green when AI Alert is enabled and blue when it's disabled. I kept it on at all times, but you don't have to.

I'm a bit sceptical about how useful a brake alert function is – but I can't see any downsides.

Runtimes

The light has seven modes, from a 10-lumen 'femto' blinking mode that will last a claimed 60 hours to an 80-lumen always-on 'blast' mode for four hours.

It's tricky to comment on quoted runtimes as they can vary in real life, with factors like temperature affecting things, but in ideal conditions I managed four hours, after which it quickly went into economy mode.

We did have an issue with the first unit we received, which wouldn't charge again after being run down into economy mode. Lezyne sent us a replacement, which it would supply as part of its two-year warranty, and this worked without issue.

Lezyne managed to reset the original light though couldn't tell us what had actually gone wrong. But you've always got the insurance of the warranty, which also includes the battery.

Modes

The seven modes include two solid functions: the maximum 80 lumens for four hours and 10l for 20 hours.

You also get five blinking modes: pulse (50 lumens for eight hours), flash 1 (50l) for 34 hours, day flash 1 (250l for 15 hours), day flash 2 (125l for 25 hours) and femto (10l for 60 hours). The light stays in the last mode you used when you switch it back on again.

From those you should be able find one that offers the happy balance between visibility and blinding whoever's behind you, whether by day or night.

I found flash 1 just about perfect for my needs, which is mostly daytime riding with companions. You'd probably use the Femto mode when you've nearly run out of battery, or were riding for 60 hours straight without a backup light or means of charging.

Day flash 1 is extremely bright when you switch it on indoors, and is ideal for riding in bright sunlight or in traffic conditions where you really want to be seen.

The active alert – or 'I'm braking, people' – mode is 250 lumens, which is a pretty obvious change to alert other road users, except when you're riding in the day flash 1 mode.

Charging

Charging is very easy. The bracket acts as a waterproof cap for the USB-C's rear charging port, though the light isn't supplied with a cable. I'm happy with that as I've got loads, but it's worth bearing in mind.

While the bracket means the light has a very impressive IPX7 rating, it does mean you can't charge it on the go. Though given the runtimes and the sort of riding I do that was never an issue for me.

Value

There's no getting away from the fact that £75 is a lot, even for a light with brake-sensing technology.

But you don't need to spend this much.

The Ravemen TR200 Smart Alert with Brake Detection costs £49.99, Magicshine's Seemee 200 Version 2 is £39.99 and Gaciron's W12BR-200 Smart Brake Warning Bicycle Shelf Braking is cheaper still at just £22.15.

While all of these have a braking function, they're not as well made from the same material nor are their mounts as elegant.

The Exposure Boost-R with ReAKT and Peloton is probably more directly comparable, thanks to its aluminium construction and well-designed mount. It retails at £100 but has the addition of a 'peloton' function that automatically dims the light when it detects a front bike light right behind you.

Conclusion

I really like this light. Its modes cover pretty much all situations, it's solid, beautifully made and totally waterproof.

Its saddle-specific design means there is the obvious limitation to where you can mount it, and beam and saddle bags are unlikely to be compatible. I'm also sceptical about how useful the braking function is, but it can't do any harm and it does it very well. Either way, it's a great light, and while the braking function contributes to a hefty price, overall I think it's worth the cost.

Verdict

Extremely bright, well made, waterproof and an excellent bracket, even if you're on the fence about braking technology