This article is from the Misc Bicycles FAQs, by various authors.
From: email@example.com (Brent Chivers)
Months ago I told someone in e-mail that I'd eventually be posting
a description of my setup. Well, that bike got stolen [8-(], but
I've done it all again, and this time a little better. So here's
one kick-ass home-brew setup:
1 bumper-mount 55-watt halogen driving light (These are sold
in pairs. Find a friend, or let your first bike get stolen.)
1 red utility light (Looks like a generic replacement taillight
for an old pickup truck.)
12-volt power source -- I'm using 1 or 2 sealed 6.5 amp-hour
2 toggle switches
bolt -- replace handlebar/stem bolt to mount the headlight
Velcro or equivalent (I think I used about 3 yards.)
[pipe-wrap foam insulation]
The driving light mounts rather nicely through that stem bolt.
You'll probably need to find a longer bolt at a hardware store
so that it can reach thorough the lamp bracket.
The taillight will probably be an easy mounting job. Mine was made
with a right-angle bend in its bracket. This mounted nicely to the
seatpost bolt (this bolt needed to be longer too -- bike shop had one)
and then the rear rack on my previous bike. On my present bike, I
straightened (unbent) the bracket and mounted the light on the rear
brake bolt. This points the light up at an angle, rather than level,
but maybe that's even better?
The batteries hang from my top tube. They sit in little "baskets"
of Velcro hooks, and soft strips of Velcro loops go over the tube
and also around the front end (to keep the batteries from sliding
back and forth and swinging side-to-side). I used 2-inch wide
Velcro. It was the widest I could find, but it seems to be more
than adequate. I have 2 strips (front and rear) around each battery
over the top tube. And one more long strip along the sides of the
batteries around the fork stem. To describe the little "baskets",
picture the rectangular battery suspended just below your top tube.
Imagine a strip of Velcro around the sides of the battery, the top
rim of a basket. Then envision strips of Velcro at the each end of
the battery, going down one side, under the bottom, and up the other
side. This does involve some sewing, so find a friend with a sewing
machine. It's fairly easy, so this is your opportunity for an
introduction to sewing. As an alternative, you could just glue
the Velcro to the battery.
[Recent Mod: You know that insulating foam designed to go around
pipes? I've put a piece around the top tube. This cushions the
battery from the tube, and lets me really snug it up tight with
the Velcro. It also makes sure to insulate the exposed battery
terminals from the bike frame. I also added a short piece at the
top of the down tube, since the front corner of the battery rested
here, and I thought it could use some padding.]
Adding a rear rack and mounting the batteries back there would
probably be easier. Just glue Velcro hooks under the batteries and
loops on the rack, and loop an elastic tie-down over the top to keep
things from moving. I thought my front end was already pretty light,
so I didn't want to add any weight behind the rear axle. (My
batteries are 6 pounds each.) And I was too cheap to spend another
$35 on a rack (But the Velcro cost me nearly $20 ! 8-)
My switches are mounted on a scavenged rectangle of plastic,
sandwiched between the headlight bracket and the stem. This plastic
is soft rather than brittle, so it doesn't mind all that force on the
bolt to keep the handlebars from moving, and it was easy to work for
mounting the switches.
I expect anyone going this route won't need a lot of details on
wiring. The bike frame makes a fine ground connection, even through
the steering bearings (good thing, since automotive lights assume
their mounting points are their ground connection, and they have just
one lead!), so you just need to pick some point to ground the battery.
My batteries have spade lugs, so I have a wiring harness with sets of
female lugs for 2 batteries and a connector that mates to wiring to
the switches and frame ground. I plan to make a matching connector
for my battery charger. (It makes sense to use a polarized
My lights came from the automotive departments of discount stores.
These things tend to go on sale perodically, if you can wait.
Switches and connectors from Radio Shack or wherever. Some of the
wire I used came with the lights, and rest came from my old electrical
I don't know a source offhand for the batteries. Mine are PS-1265's
(12 V, 6.5 AmpHr) from Power-Sonic Corp of Redwood City, CA. They
weigh about 5.5 lbs each. I got five of them at a computer flea
market for $3 each. (They all seem to be good, but you never know
what you're bringing home from a flea market.)
These batteries are good for just over 50 minutes each, running both
the headlight and taillight. Full brightness through about 51
minutes. Seriously dim after 55 minutes -- still enough enough light
to attract attention, but not enough to help see road problems at
speed. Adding batteries will add time. Having separate switches for
the front and rear lights will let you stretch that time.
For lead-acid batteries, I think a 1-amp light-duty motorcycle battery
charger should be fine. If you go with NiCads, you might want
something more gentle. A trickle charger should work for either, if
the setup can sit still long enough. NiCads will cost you a lot more
than lead acid too. 55 watts from 12 volts means
4.6 amps, so they'll need to be beefy. (Consider this in your wiring
and switch selection.) Add in something for your taillight too.
There's a lot of room for variety and improvising with all this.
Here's some things I did better the 2nd time around:
separate front/rear light switches
placed switches where they are easy to use while riding
batteries are easily removable (good for day rides,
not good for locking)
can use 1 or 2 batteries -- less weight for less light-time
used sealed batteries
First time I just had 1 switch for both lights. There was an extra
hole in the taillight bracket, so that's where I put the switch. Now
I have 1 for front and 1 for back. I like this much more, as I can
conserve the battery capacity. If I'm on a trail (no car traffic),
there won't be many joggers or other bikes. I don't need the
taillight there at all, and I don't always need the headlight if the
trail is lit. On streets, I can turn on the headlight as I need it,
and the taillight whenever someone is behind me. I ride with a
rear-view mirror, so I see cars pretty far off before they overtake
me. (If you're not very aware of your surroundings, then just keep
the lights ON!)
The first time around I used a 9 Amp-Hr motorcycle battery, taped with
strapping tape to a rack over the back wheel. This gave me something
under 2 hours of light. (But it was winter. You'll get more power
from a battery when it's warm.) This battery was NOT sealed, and I
found it a major nuisance. I did not mount the battery so it was easy
to remove, and I had to be very careful to always keep the bike
upright. Even so, there was frequently acid dripping out the overflow
tube (which was routed to keep the acid off the bike, but that stuff's
still going to land somewhere). A removeable setup didn't seem like a
big issue in February, since if I did any weekday riding, it was going
to be dark when I came home (if not when I left, too!).
I have to admit that the big drawback of my setup is WEIGHT. The
lights aren't bad at all, but the batteries are HEAVY. If you want
a 55-watt light, you've got to carry some serious batteries. If
you're riding for exercise, this may not bother you. I love the
light, so I live with it.
The big advantage is that cars can't help but see you. From the way
they often wait on side streets, they must think I'm a motorcycle --
until I finally go by in their headlights. And you can really see
well enough to go 20+ mph. It's hard to overdrive this much light.
It's also a conversation starter on the METRO. It's not such a bad
bike in the first place, but everyone wonders about that light, and a
few people will even break the conversation taboo and ask about it.
This is a lot cheaper, brighter, and heavier than commercial bike
offerings. I expect replacement bulbs will be much cheaper and easier
to find too, since they're not specialty items.
From: firstname.lastname@example.org (Giles Morris)
Anyway... I cannot take credit for much of the ideas involved in this - my
contribution was the hose clamps. Whatcha do is:
- The front lamp assembly is a standard 12V reflector bulb. Made
by GE (and others) for track lighting. It is available in 20W
and 50W versions, each of which is available as either spot or
flood beam. I use a 20W spot beam version. Because the
silvering on the reflector is not entirely opaque it should be
painted - I used several coats of spray enamel, but suspect
that matt black engine spray paint would be better.
- The bulb is held in place by two hose clamps. One passes
widest part of the bulb (2" in diameter). The other passes around the
handlebar and between the bulb and the bigger hose clamp. I use epoxy
resin around the bulb to ensure that it stays in place within the
- Wiring in my version is a very simple setup. The conducters
are soldered to the two pins on the back of the bulb and there
are simple spade connecters on the other end to match the
connecters on the battery.
- I have two alternative batteries. Both are 12V sealed lead
acid, bought from a local (Falls Church VA) battery
specialist. One will eventually live in a water bottle and is
a 1.9AH battery. The other one is a little more difficult to
mount because it is a larger 4AH version. I have it strapped
in the space frame of a Moulton.
- The rear light is a Vista Light.
Where to get the stuff:
The bulb should be in any home supplies/lighting/hardware store. I
The hose clips are obtainable from, well... lots of places. Small $.
The battery was easy for me to find locally, but I have seen many mail
order sources. I think I paid about $18 for the small and $30 for the
The rear light is available in most bike shops.
Summary: I am _very_ happy with the result. Thanks to all here who
contributed. It seems to work about as well as my wife's NightSun for
a _lot_ less money.