Build your own Bike Lights
© Ally Mitchell, September 2004

I'm not sure why I ended up building my own lights - in spite of knowing nothing about bulbs, voltage, burn times, overvolting, soldering, battery types or chargers. Maybe because I couldn't afford the likes of www.lumicycle.co.uk. Maybe because it's no fun going out on a night run with crap lights. Or maybe because I'd talked about it so much that I convinced myself I could actually do it.

Seriously, I'm a total beginner with anything electrical - what follows is a basic set of instructions to build a set of decent bike lights that won't leave you in the dark...(I'll get ma coat...).

Research

I spent a lot of (work) time searching the Internet for hints, and I'm a regular addict of www.singletrackworld.com. The advice - some useful, some totally irrelevant, all taken on board - I received really helped me. Cheers folks. The other main place I looked was on www.bikemagic.co.uk  which has some DIY bike light article. And yet another source for me was a website by someone who also built their own lights - see http://wedlake.pwp.blueyonder.co.uk/lights.htm.

I also did a lot of research into bulbs, batteries and chargers - details below.

Other useful sites:

www.singletrackworld.com - info
www.bikemagic.co.uk - info
www.myra-simon.com/bike/lights.html - info
www.multicell.co.uk - batteries
www.ricam.co.uk - bulbs
www.thelightbulb.co.uk - bulbs
www.lumicycle.co.uk - useful info on beam patterns, chargers and ready-made lights
www.cellpacksolutions.com - batteries and advice

Materials

Battery: In the end I decided on a pre-built 13.2v 4100mAh NiMH battery pack from www.multicell.co.uk for £47.50. I felt that NiMH was worth the extra cost over sealed lead acid (SLA) batteries because of the reduced weight and bulk. NiMH also doesn’t suffer from 'memory effect' that NiCad cells have - you can charge NiMH batteries no matter how much charge they already hold without damage.

Charger: After much searching I relented and purchased a smart charger from Lumicycle (they’re very useful guys, phone 'em for a chat if you’re not sure about something). If you're not bothered about a smart charger, Multicell will do you a standard charger for £12.99 but I think it's worth the extra for a smart charger - removes the risk of overcharging and damaging your battery, but this is the easiest place to save money if you’re really on a budget.

Lamp Units: I ended up making mine from some plumbing fittings from B&Q. For each lamp unit you will require one 40-32mm waste pipe reducer AND one 32mm access plug. I based my system on 2 lamp units. I also splashed out and bought a couple of proper handlebar clamps from Chain Reaction (£3.49 each), but you could just as easily zip-tie the lamp units to the bars. Or your head.

Leads: Also from www.multicell.co.uk, I got leads for connecting the battery to the light units. I ordered:

• 1 x 60cm lead from battery
• 1 x 30cm lead, splitting into 2 further ends of 10cm each (to connect to light units)
• 2 x 5cm leads, for connecting lamp units.

* See Figure 1: Lead Diagram

Figure 1: Lead Diagram

Wiring required:

1/ a 60cm lead from the battery, ending in one part of a connector (A)

2/ the corresponding part of the connector (B) attached to a 30cm long lead, ending in bare wires (used to attach to charger.)

3/ another corresponding part of a connector (B) attached to a 20cm long wire (point 3 to point 1), splitting into two leads each about 10cm long and each ending in a connector (A)

4/ 2 leads: each approx 5-10cm long, one end the corresponding part of a connector (B) and the other end in bare wires (these bare ends to be soldered to lamp units).

Miscellaneous: There are other wee bits that are essential.

• Bulb holders: these hold the bulbs themselves. Come with wiring attached.
• Switches: essential if you want to switch them on/off individually. I got mine ready-made into the wiring from www.multicell.co.uk to save a bit of faffing.
• Water bottle: for putting battery in to carry on bike.

Notes / Tips:

• It's a good idea asking www.multicell.co.uk to make up all your wiring for you - I did because I ain't that confident with soldering myself, and it also saved a lot of hassle and time.
• When you buy the waste pipe reducer and waste pipe plug, buy a spare one - you'll probably  make an arse of the first one...
• Keep any polystyrene packaging that your light components arrive in - they are very useful for packing out the battery when you stick it in the water bottle.
• Take you time.
• Don't lose the rag...
• Don't throw your tools across the garden...
• Beer/coffee/jelly babies are good.

Construction

1. Get your 32mm waste pipe plug. Drill a hole in the centre to allow the bulb pins to pass through.
2. Fit the ceramic lampholder to the 'inside' of the plug, such that the holes where the bulb filament go are visible through the hole you've just drilled in the centre.
3. Solder the wires from the lamp holder to the appropriate terminals on the toggle switch and your own wiring.
4. To check that it's all working, plug in a bulb, connect your battery and switch on. Hopefully it all works. Now to fit it in the holder.
5. Remove the bulb again. Take your 40-32mm waste pipe reducer and prise off the front cap (this WILL probably be tight). Don't lose the rubber O-ring - you'll need it later.
6. Drill a hole in the side of the waste pipe reducer to fit your bar clamp (or glue it to the side of the waste pipe reducer (not recommended!).
7. Push the waste pipe plug assembly into the rear of the waste pipe reducer, as far as it'll go. Now, refit bulb into the front of waste pipe reducer, put rubber O-ring on top of bulb, and refit front cap (this should hold the bulb in pretty securely).
8. At this stage your 'bulb holder' should be almost complete: the bulb is in, the bar clamp attached, but all the wiring and toggle switch will be hanging out the back. You now need to mount the toggle switch and seal up the back of the lamp unit.
9. I found it easiest to mount the toggle switch in the side of the waste pipe reducer - not the neatest, but the only way I could see to do it. Drill a suitable hole for the toggle switch lever to pass through and secure the toggle switch.
10. Tidy up the wiring, cram it into the rear of the lamp body, and seal over the rear of the lamp unit - I used duck tape and cable ties to secure it all, not the prettiest, but still waterproof after 6 months use.
11. Et voila! One lamp unit. Repeat for another one as required.

Info on Bulb Power / Beam Spread (from www.lumicycle.co.uk)

Lumicycle's Commonly Recommenced Bulb Combinations:
5w Spot/ 12w Spot: Great Little combo Max. run time 8.5 hours Min Run Time 2.5 Hours
12w Spot/ 20w mid: Recommenced combo for road use. Also good for off road riding.
12w Spot/ 20w flood: Recommenced off road combo.
12w Spot/ 35w Spot: Recommenced combo for fast A road riding or for rapid downhill descents.

Ally's Commonly Recommended Bulb Combinations:
10w mid (18°) / 20w flood (36°): 10w mid good for climbing and on-road use. I find the 20w flood wastes too much light out to the sides - some people like this, I didn't.
10w mid (18°) / 20w mid (18°): good combo for longer runs. 10w good for climbing, etc. but switch to the 20w for tricker bits. I used this combo for a 24hr race - 2 laps of 1hr10min each on the one charge and the lights weren't even fading.
10w mid (18°) / 35w mid (18°): combo I use most often - 10w sufficient for most stuff. I only use the 35w on descents; it's like riding in daylight! Gives enough battery life easily for a 2.5hr run, switching between the two bulbs. Even if certain people in SBC think anything near 40w is for pansies...
But I'd recommend buying bulbs in bulk and trying out to see what you like best.

GOOD LUCK! EMAIL ME IF YOU’RE REALLY THICK (SORRY, I MEAN EMAIL ME IF YOU’RE STUCK OR UNSURE ABOUT SOMETHING!)

Pictures of the finished article:

Back to Top

Feedback

Terms of Use