Cateye X2 Kinetic

The Cateye Rapid X2 Kinetic has a sensor designed to make it act as a brake light for your bike. In terms of build quality and the features you'd want from a rear light, it's a good design, so it's a crying shame that the brake light element is so sensitive as to be not fit for purpose in real-world applications.

The ability to signal to other road users that you are slowing down is, generally speaking, a good thing – it allows them to react sooner, reducing the risk of collision. Over the years various firms have tried to bring this functionality to the lightweight, minimalist world of the bicycle with limited success – varying from the frankly awful Sigma Rear Brake Light to the 4.5-star Lupine Rotlicht and See.Sense Icon. Now the 800lb cycling accessory gorilla has waded into the smart rear light market with the Rapid X2 Kinetic.

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Physically, and in brightness, flashing modes, charging, run-time and most other aspects, the Rapid X2 Kinetic is identical to the recently reviewed Rapid X Rear. The only difference is that instead of being able to manually choose the 50-lumen high mode, it only comes on for 2.5 seconds when the accelerometer detects you are braking.

So the question must be: for an extra £13 over the Rapid X, does the X2 Kinetic actually work? Yes. And no. It's complicated.

On smooth or rough roads, fast or slow, going uphill or down, the brake function would activate. Unfortunately, it would also do so when accelerating or riding at a constant speed. That's not to say it didn't 'work' – when decelerating under braking, the brake light came on every time. The problem is the false alarms.

You could argue that any light is better than no light, but when the proposition is that you advise other road users of your deceleration, any incidence of false alarms is not going to deliver the desired reaction from them. If you're in a bunch ride and those behind realise your light is going off at random intervals, they won't trust it. A following driver will wonder what on earth you are doing – that it's simply an erratic flash.

> Read more road.cc reviews of rear lights here

I tried mounting the X2 Kinetic in a number of locations – rear of the fork, seatstay, seatpost, on different bikes and at different angles – all with the same fundamentally random results. In all cases even moderate braking would trigger the 50-lumen mode – but also minor and major bumps and changes in orientation would as well. To me, this fundamentally undermines the USP of a 'brake light'. Plus, with no option to manually select the brightest 50-lumen mode, in effect you're getting less light for more money.

As the form factor, installation, battery life and brightness are all winners, hopefully Cateye will release an updated version with a more reliable accelerometer to deliver on the promise of a functional, reliable brake light. Until then, I'd suggest you look at the Rapid X.

Verdict

A good light but it doesn't deliver on the promised reliable brake light functionality