Advice on Building LED Front MTB Light ??

Hi all….

I need advice on building myself a front light for riding my MTB off road. The benchmark I'm looking to hit would be a Hope that runs 4 x LED's from a 7.4v Li-ion battery pack. It claims 960 lumens which looking at the LED flashlight market seems reasonable. Unfortunately I'm in no way an expert on flashlights or LED technology, which is why I'm posting this plea for advice and suggestions.

I have a friend who's an engineer with some great kit so I'm capable of building the housings for the light and the battery pack. What I need is advice on what to build. My intension is to use my LED front I already have for the road, and then switch on the new light when needed. This is so I can get as much light and flood without offending other road users. Most existing high power bike lights have dip and main beam for this purpose but if it makes life easier for me I'll use 2 lights.

My electronic skills are fair so I don't mind building from scratch if someone could list me components to buy although one avenue I was toying with was to buy the lamp unit for a Spiderfire x550 with the 5 x Cree Q5 LED's. Thinking if I then bought an aluminum torch at the right diameter, I could use it to build from. My only problem with this is that I'm not sure what I'd be buying. Looking at screen shots of the unit you can see the spring on the back so would that mean that wiring it to 2 x 18650 batteries would provide my light?

Basically, my knowledge is very limited in this area but I'm hoping as with all other forums I belong to that anyone who knows a way to help me build what I need will pass on their wisdom happily.

To summarize, I need a light as bright as I can get with flood having a slight priority over spot although I'm guessing at the 1000 lumen mark distance won't be an issue. My unit will need to be not much larger than a 50-60mm flashlight head. The battery pack needs to be housed separately so I'll need to be able to plug it into the light unit and be able to recharge it. Being able to have the light dipped for the road would be great but not a necessity as stated.

Please help me in any way you can people as I need this light but refuse to pay over 300 hard earned British pounds for it.

Thanks in advance

I'm in the same boat, fella I refuse to shell out that amount of pounds,I've got a 2D cell maglite that i'm going to mod once I figure out the finer details,

Well starting from scratch now I would want to be using Cree XPGs as they are the latest and greatest. 3 should match the Hope4 4 should be an improvment. Cutters are your best bet for supply at the moment and they do boards with 3 or 4 leds and have matching optics. Still a bit new to know what optics are good or not.

For a driver on a bike light you can not beat TaskLED offerings, loads of features and interfaces designed for biking. For a 3 or 4 XPG setup I would look to use 4 18650 Cells and a bflex. With the older leds the same number of cells as leds would not be recomended but all the indications are that the reduction in Vf of the XPGs makes it a very viable option with the added advantage that it will drop out of regulation and automaticaly dimm after 80-90% of the runtime.

Personaly I use cheap 18650 cells from DX but this is a very emotive subject as some people give them a bad time but I always buy more than needed which at the proce is a virable option. Cheap 2 cell charger also avalible on DX.

There is a biking specific subforum here which you should check and the MTBR lighting forum is very good.

get the DX bike light.

It in fact is what You search for: a nice looking housing, led+reflector, electronics, charging equipment.
All together now WORKING and for a price a nice housing alone would cost You.

If it ever fails, or if You ever decide to upgrade/improve (with other led, other focusing device, driver that pushes the led harder, ...), You still have the nice looking housing.

Much better than getting a light and use just its head. That was 1-2 years ago, when that m.o. could be considered the best way to build a light.


Sure, if You want to use individual led (why? Do You have the info on how to align the individual beams differently? Else it does not make sense to use several led), there is only the "light-head" way of building.


PS: mag head modding leads to much too heavy heads. That is also 2 years old modus operandi

yellow said:

get the DX bike light.

It in fact is what You search for: a nice looking housing, led+reflector, electronics, charging equipment.
All together now WORKING and for a price a nice housing alone would cost You.

If it ever fails, or if You ever decide to upgrade/improve (with other led, other focusing device, driver that pushes the led harder, ...), You still have the nice looking housing.

Much better than getting a light and use just its head. That was 1-2 years ago, when that m.o. could be considered the best way to build a light.


Sure, if You want to use individual led (why? Do You have the info on how to align the individual beams differently? Else it does not make sense to use several led), there is only the "light-head" way of building.


PS: mag head modding leads to much too heavy heads. That is also 2 years old modus operandi

Click to expand...

Sure he could get the DX bike light, that's always an option, but if he has the ability to get a housing made and is interested in making his own light then the possibilities are endless!

OS, I would highly recommend heading over to forums.mtbr.com and looking at the DIY lights section. One of the classic build styles is the "achesalot" design, which I've made one of myself. Really simple, not perfect, but I find it to be a great light. Guys like troutie on the forum also offer pre-made housings, but if you aren't interested in that you can still learn a lot from them. A bunch of them, like troutie, are also located in the UK! Quad die emitters (P7/MC-E) can make a build simpler as you have less individual parts to deal with, but there is less flexibility with beam pattern. I'd also think that your engineering friend could design you a housing which would center the emitters and optics/reflectors, thus simplifying the build for you.

Drivers from www.taskled.com are quite reliable and would offer you mutliple levels of output if desired. There are also sources for single level drivers though, or other options like the BuckPuck which can be wired with a potentiometer (or a multiposition toggle and some different resistors) to give you a very simple user interface.

Cheers so far guys....

I knew i could count on ya. I definately want to build my own from scratch. With work and 4 kids at home i need a reason to spend a few hours in my garage ON MY OWN !

Keep posting though guys cos all these different opinions will hopefully lead to me building the best light i can.

What would be really helpful actually would be a generic list of the components i will need (seen as im a novice at light building). i.e. LED, reflector, driver etc.

Thanks guys....Together we'll make me a light....

so the advise is: everyone should use outdated designs?
(Ones that give a 100 % chance of much more additional efforts, running to get parts, not planned work to cover for problems not considered be4, ...)
(& that are more expensive in the end and that look homemade as a "plus")
to learn and then possibly be able to build something good later - with enough insight on light building?

Why not skip that whole part and start with the easy actual building alternatives?
:thinking: