BMW K 1600 Adaptive Headlight

By Kevin Ash - 04/10/2012

How do you get a headlight beam to stay level when a bike is leaning over? That‘s what BMW has managed with its latest raft of world-leading technology on the K 1600 series.

Main beam is looked after in the conventional way, by a pair of halogen bulbs, but dipped beam is much more complex. The light comes from a xenon projector unit which points upwards at an approximate 45 degree angle. Above it is a reflector mirror which aims and focuses the light beam forwards. The reflector moves and is controlled by stepper motors so it‘s capable of pointing the beam in different directions - these motors are operated by a headlight management computer which is fed a range of information.

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One task is to keep the headlight at the same level regardless of how the bike is loaded. There are two mechanical sensors in the front and rear suspension which measure the average amount the suspension is compressed at each end. With this information the headlight computer can adjust the reflector to keep the light at the right level, high enough for good vision without dazzling oncoming drivers, even with a well-fed passenger on the back of the bike.

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But the really clever bit is what happens when you lean for a corner. The K 1600s are fitted with a solid state, on-board gyro which tells the computer the bike‘s exact lean angle. The computer then instructs a stepper motor to turn the reflector in the other direction, tilting the beam sideways just enough to compensate for the bike‘s lean. It can do this for lean angles up to 25 degrees in each direction.

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This on its own is a major advance, but the system even more sophisticated than that. As well as lean angle the computer is also told how fast the bike is going, and with these two pieces of information it can work out how tight the corner is - 20 degrees lean at 80mph means a much broader curve than 20 degrees lean at 20mph. Knowing this, it now aims the headlight into the turn, left or right, to light up as much of the road ahead as possible. It can do this by up to 15 degrees from the straight ahead, and it happens at the same time as the beam is being kept level.

A final neat touch is the light unit‘s ability to switch to right hand drive roads. Take your British K 1600 to France, select right drive on the dash and the reflector clicks to one side so dipped beam no longer kicks up to the left and dazzles drivers, and you no longer need to tape up the light cover. The only downside is the adaptive lean ability no longer works in this mode.

The difference with the BMW system is huge in how much of a twisty road you can see at night, compared with a conventional light plunging the road into darkness as you lean. It‘s like night and day...

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