OEM HID, an ambiguous benefit

[johnlt]

This relates to safe riding so I'm posting it here.

 

The ambiguity comes from the dark-adaptation your eye experiences when looking at a projected HID light. Most OEM HID lights use projector lenses. This is true for both the OEM vehicle and OEM Aux lights. Their projected beam pattern has a very sharp “cut-off” line to keep from blinding oncoming drivers. I have found that the very bright near-field causes a significant decrease in dark-adaptation such that I’m nearly “night blind” above the cut-off line. My Lexus HID is a good example. Even though the near-field is significantly brighter than my 4-Runner incandescent lights, I think I can see the “full field” better with the 4-Runner. Another example is my 1150 RT. I had PIAA 1100s under the oil cooler and PIAA 910s with 100W bulbs above the mirrors. My “rider’s view” at night was far superior to my 06 GSA with HID low and high beam plus two Hella Micro HID aux driving lights. Has anyone else experienced this phenomenon?

[smiller]

The cutoff effect is very severe on the factory K-GT HID, and added to the lean effect of a motorcycle it can actually be dangerous (plunging sharp corners into absolute darkness on rural roads) if aimed according to factory specs. The problem is pretty easily solved by aiming the headlamp higher, in which case it works very well... but of course aiming the headlanp higher negates the value of the sharp cutoff. A good example of good intentions gone wrong.

 

The 'non-approved', illegal, immoral HID conversion on my 1100RT actually works better in some ways. Because there's some vertical spillover I can actually aim it lower... and thus it may well be less annoying to oncoming drivers than the DOT-approved setup...

[Survived-til-now]

I have a HID conversion that is in truth probably in a grey area of legality i.e. retrospective conversion is not mentioned in the regulations but you MUST not dazzle......

 

I agree with your point about cut-off but look at the practicalities of day to day riding on congested roads. The oncoming cars' lights effectively take out your peripheral vision and the undoubted increase within the beam cut-off in not only light but the colour of the light (enabling you to see mud on a dark road) makes it an undoubted winner for me.

 

I spent a lot of time setting up my lights so as not to dazzle on-coming traffic - so successfully that after my set-up I never get flashed by on-coming vehicles. As far as following a car in front is concerned, the sharp cut-off enables you to be very precise in aiming the beam so that it doesn't blind drivers via the rear view mirror. It is not quite as clear cut when things come to side mirrors and I do very occasionally get flashed by a driver I have overtaken, having caught him or her in a side mirror. I did set my lights even lower the first time it happened but then got nearly taken out by inattentive drivers who pulled out as I was passing - and so I now aim a little higher and if the penalty is an occassional flash once in a while then its a price they pay to keep me alive.......

[Ken H.]

I think your concern is a valid one. One I’ve brought up (and generally was poo-poo’ed) before.

 

As you increase the amount of light in the illuminated area in front of you, your eyes are going to adjust and the delta/contrast between the lit and unlit (e.g. to the sides) areas is going to go up. I.e. the dark areas (where creatures lay for example) are going to be harder to see into. Truly a situation where too much light is possible.

 

It’s a long recognized phenomena in flying, but hasn’t made it into the physic of the riding world yet where if some light is good, more and more has to be better, excess is assumed.

 

[ratfink]

I have an 80 watt bulb in the stock r1100rt housing fed through heavier wiring and a relay, the cut off is such that it doesn't bother on coming drivers. I also have two hella driving lights that practically turn night into day. The problem is when I dip my beams it is like "Who turned out the lights". Combination of age, sensitivity to oncoming lights and reduced night vision. really I avoid riding at night but sometimes it is necessary if one is determined to ride alot.

[johnlt]

When you put aftermarket HID bulbs in OEM reflectors, sometime you may not get the sharp cut off because the beam pattern is different than the "point source" incandescent bulb. In OEM HID applications including aux lights, they generally always use a projection lens to provide the cut off pattern.

[Joe Frickin' Friday]

OK, so...HID's are bad?

 

What's the alternative?

[Mike]

This relates to safe riding so I'm posting it here.

 

The ambiguity comes from the dark-adaptation your eye experiences when looking at a projected HID light. Most OEM HID lights use projector lenses. This is true for both the OEM vehicle and OEM Aux lights. Their projected beam pattern has a very sharp “cut-off” line to keep from blinding oncoming drivers. I have found that the very bright near-field causes a significant decrease in dark-adaptation such that I’m nearly “night blind” above the cut-off line. My Lexus HID is a good example. Even though the near-field is significantly brighter than my 4-Runner incandescent lights, I think I can see the “full field” better with the 4-Runner. Another example is my 1150 RT. I had PIAA 1100s under the oil cooler and PIAA 910s with 100W bulbs above the mirrors. My “rider’s view” at night was far superior to my 06 GSA with HID low and high beam plus two Hella Micro HID aux driving lights. Has anyone else experienced this phenomenon?

 

I think there's something to your observations. I haven't ridden a motorcycle with HIDs, but have had three cars with HIDs. The Lexus I had had a very abrupt cutoff, and the phenomenon you mention was definitely an issue. My Subaru STi also has HID low beams, but their cutoff is not as abrupt. They don't seem to have the laser intensity that the Lexus's did, but I think they provide better overall lighting. The best HIDs of all were the aftermarket ones I installed on my VW R32 . . . they provided excellent levels of illumination and had a cutoff that didn't dazzle, yet there was just a bit of diffuse light up higher that was just about perfect.

 

One thing I have seen on cars--and this apparently is the case on some BMW motorcycles as well--is that the HID low beams are aimed much too low. You don't want to "dazzle" oncoming motorists, but getting them adjusted properly can make a huge difference in how well they work. With all my HID-equipped cars, I have spent a fair amount of effort making sure they're aimed properly, and it's made a big difference. I would expect the same to be true with motorcycles.

 

 

[johnlt]

One thing I have seen on cars--and this apparently is the case on some BMW motorcycles as well--is that the HID low beams are aimed much too low. You don't want to "dazzle" oncoming motorists, but getting them adjusted properly can make a huge difference in how well they work. With all my HID-equipped cars, I have spent a fair amount of effort making sure they're aimed properly, and it's made a big difference. I would expect the same to be true with motorcycles.

 

I agree Mike. One thing I did on my Lexus was to have the dealer adjust the low beam to the "high" end of the spec range. Just sufficient to stay legal. That helped a lot.

[Penforhire]

I think your observation is valid. But given the choices I'd still rather have more light, with near-sunlight color, on my path at night and be a bit blinder beyond the cut-offs. I suppose there can be a better solution, a more gradual lensed cut-off.