Contemplating some rack based lumens

Just mounted a new Gobi roof rack and am now considering adding some lighting. Other than the ‘bro look’, the functional purposes would be roadside lighting for night driving; watching out for those night critters. A bit of scene lighting for camping might be nice too.

I’m debating starting with light bars from one of the big guys. Unfortunately, they don’t make a 14-16” bar and the center section in my rack is only 17” wide. I could mount a full 40”, but it would be a bit forward of the support bars. Also, all my light in a single bar makes me nervous for cost of repairs. I’d probably end up with two rear facing pods or small bars too.

Any other pros or cons of doing a single large bar vs. 3-4 smaller bars/pods? What about brands, any reason to pick one over the other in the Baja Designs, Rigid Industries, Caliraised trio?

Thanks guys.

 

Biggest issue with a roof mount bar is glare off the hood due to the traditional basic forward facing optic. Diode Dynamics TIR optics offer better focus, meaning higher focused output which reduces hood glare. I’d take a look at their light bar offerings.

 

Thanks Crash, your lighting opinions always warrant follow up.

 

@crashnburn80,

Crash, I did a wee bit of comparisons and the first thing that jumps out at me is the cost differential. DD runs about 33% of the cost of a Rigid SR-Series; this is the 40" comparison. It also runs about 57% of the brightness of the Rigid at 10M. And finally, the DD draws about 70% of the power of the Rigid. So per lux, it's a much better $ value, but slightly less efficient based on power draw. The overall output of the Rigid is about 75% more than the DD, so that's the trump card I suppose. And of course, Rigid has their E-Series Pro that comes close to doubling the output of the SR Series.

I do like the price point of the DD product. I just don't know much about their quality. Rigid, BD, and Cali seem to be the most common out there, but that's only to be used as a tiebreaker if I don't find an alternative that I'm happy with. Sort of like Prinsu an UpTop are the current front runners in racks but I bought a Gobi because it's essentially indestructible. It's not as great a value as the other two, but it suits my use case better.

Is my assessment essentially correct regarding value? Neither of the two vendors post vertical beam angles, which I gather is what you're suggesting DD does a better job with. TIR is a great concept to apply here, provided you can efficiently remove the halo'ing effect. I'd have to pull out my spreadsheets and really start digging into data to get a better analysis.

 

Are you comparing driving beam to driving beam? Or are you comparing DD Driving to Rigid spot/driving combo? For a driving beam you'll find that the Diode Dynamics product is high intensity. You'll also notice that Diode Dynamics uses an SAE driving pattern, whereas Rigid does not. Rigids driving beam is 48 degrees horizontal on their 20" bar vs Diode Dynamics 20 degrees horizontal on their 18" bar. Rigid's larger 20" driving bar produces 1127 lux at 10M, vs Diode Dynamics smaller 18" bar produces 1650 lux at 10M, aka 46% higher intensity from a smaller light bar. Diode Dynamics does publish the vertical spread spec of 8 degrees, Rigid does not publish the vertical spread spec.

The issue with hood glare is that light cannot be controlled if it is not reflected. Bouncing the light off a control surface is the only way to precisely target where it is directed. Baja, Rigid, Cali all use basic forward facing optics as shown in the legacy reflector below. The red beams are light that is not controlled because it was not bounced off an control surface, meaning poor pattern control and a lot of bleed off glare. Those red beams are what is going to bleed off the hood and cause excessive hood glare as the light is not going where it is aimed. KC actually has an even better design on their Pro6 lights with massive reflectors and they point the LEDs backward into the reflector for unparalleled pattern control so that 100% of the light is reflected and controlled. However, the design is more bulky and more expensive than Diode Dynamics TIR optics. If wanting to minimize hood glare for better functionality in an overhead light, I would look for a design that works to confront froward escaping light by ensuring it is reflected, and the only two contenders of designs that do that are Diode Dynamics and KC.

 

Doing some Saturday morning surfing and “figuring”. I think I’ve turned corners just a little and will likely start with a grille bar from DD. This gives me a functional light for on road use if necessary. What I’m confused about is the SAE compliance. They list SAE/DOT compliance up to 12” on their website. But in the notes of all sizes they say ‘when installed as 6” pairs’ they are road legal (check local state etc). Is a single 30” a no go then?

The roof rack is really calling out for a curved bar in order to fit well, so that’s a challenge as DD doesn’t make one.

 

Correct, the single larger bars (18”+) are not compliant as the intensity values are too high from a single light. They do have a compliant driving style beam pattern (not legal), which is more ideal than some light bars ‘driving’ pattern which is often just a spot and flood combo. Driving lights are a high beam, so they should never be run with forward traffic, meaning the legality may be less important unless you have state inspections.

 

So I guess it comes down to putting in two 6” bars if I want street functionality. Nominally, I would want them for highway cruising with low beam supplementing. Best scenario since it would be two bars now is that I could tie each side to blinkers and have them separately turn on as cornering lights: “old man eyes these days”. But that then challenges highway use. Hmmm. I wonder if I can change my fogs to get that wider pattern for cornering lights.

Ultimately, in a highly regulated environment, it makes supplementing very difficult.