For a while now I’ve had my eye on the B&M Toplight Line Plus with Braketec. The standard Line Plus uses a pair of LEDs and some clever optics to produce a line of red light rather than just two spots. The logic behind this is that diffusing the light into a line makes it easier for following traffic to judge the distance of the light, whilst also being less likely to irritate those following.
The Braketec version of the light also features a signal processor which detects the change in the dynamo AC frequency when the bike slows rapidly, momentarily increasing the brightness of the light to indicate the rider is braking. Whilst I have my doubts about the usefulness of turning signal lights for bicycles, I expect that a brake light will at least be correctly registered by following motorists despite the relative rarity of brake lights on bicycles. However, the main reason for wanting to try this light out are not because of the potential minor safety benefits which come from the brake light function, but because it is quite a clever idea, executed in an interesting way.
The light is bright, although the rack mounting on the Brompton makes for rather poor side visibility. Thankfully this is made up for by the reasonable side visibility of the front light an the reflective sidewalls of the Marathon Plus tyres. The brake light function works without any calibration required, regardless of whether you are using a hub dynamo with large wheels, small wheels or a bottle dynamo. It just works.
The effect is pretty clear in the video, but viewed by the human eye rather than through a digital camera it is much more pronounced.