Your commute is relatively short so a ni-cad system is an okay way to
go.
The big advantage of generators is you always get power when you are
moving. There is no need to remember to recharge your battery or to
remember to bring it along. And you get power for all night rides.
There just aren't any commercial rechargeable bike light systems that
will last all night. Most are good for up to 3 or 4 hours at low beam
setting, etc.. Good generators don't add a noticiable amount of drag.
You are typically riding a little slower in the dark anyhow.
There are many different kind of generators!
1: The classic bottle shaped tire drive model. These are the worst
ever. maximum mechanical drag in addtion to the electromagnetic drag
created by the electricity being generated. Cheap. They wear out the
side walls of your tires if you don't align them just right. I just
bought a used bike where some previous owner had the drive wheel of the
generator running of the rim inself! Arg. 1 ruined aluminum rim not
to mention nearly no power because of the metal to metal slipping, and
don't forget the noise! You can buy a rubber cap to put on the drive
wheel that softens the contact area and increases the drive wheel
diameter which means less voltage being generated.
2: Hub generators. There have been many verisons. Sturmey Archer
probably made the most. Very low power output. heavy. I convereted
one to quick release and wired it into a Wonder light. I have a couple
of others on old Raleigh 3speed bikes. Pretty worthless as far as the
light output goes.
Shimano has several models listed in their catalogs. Hard to find for
sale in the USA.
The best is the german make Schmidt. I got one for my wife for her
'midnight century' rides. These are great hubs. About $200. Peter
White Cycles is the usa distributor. This is a relly nicely made unit.
I built up a spare wheel so we can just change out the wheel for the
night rides. There is nearly no noticable mechanicial drag. You would
not notice it while riding when the light is off. When the light is
on, there is the electromagnetic drag which is not really noticable
either. no noise! The hub is sealed up well enough so I don't think
rain would affect it. For the power concious, a 3 watt generator would
take 3 watts of your pedal power, plus a little extra for energy
conversion. But you are probably putting over 100 watts into riding.
okay thats highly subjective. 25+ for the super leisurely rider, to
500+ for lance in a prolog.
3: Bottom bracket generator. Sanyo made these nice units. The french
coppied it: soubitouz (sp). This bolts on where a kickstand would go.
It has a larger drive wheel than the bottle type. The generator is
actually inside the drive wheel. Runs on the tread of the tire.
Minimum mechanical drag. Pretty quiet. I used on for commuting for
years. My only complaint was it would occasionally kick off when I hit
a hard bump. that is a function of frame geometry, how close does the
generator get mounted to the wheel. I got good at flipping the lever
with my toe. I have seen some worn out from excess road debrie.
4: I have another oddball generator. Mounts on the rear hub like a
drum brake. Panasonic. I can't say this is any good. Lots of
physical drag. Really heavy. Probably cuts 3-4 mph off my speed.
Won't fit on many bikes because of clearance issues. Forget any
aluminum bike, quick release wheel, etc.
Most generators are rated at 6 volts, 3 watts. But that depends on
speed. I do have a special bottle generator that is rated 12 volts for
a florescent light.
All generators make more voltage as you go faster. To keep bulbs from
burning out at faster speeds (over ~~15-20 mph) you need a regulator.
The ideal regulator is a Zener Diode. This is a special solid state
diode that limits voltage to a preset level. They are available in
countless voltages and power ratings. The alternatives to a zener is
1: ride slower. 2: switch on more lights as you go faster. You will
still burn out bulbs using these 2 methods.
Peter White sells the Lumotec lights that have the zener diodes added
inside.
Also Peter White's website has a bunch of charts comparing drag, output
vs speed for various products.
Most generators will hit the prescribed 3 watts of output at about 12
mph to 15 mph. If you are doing 35, that would power 3 head lights!
My panasonic generator came with a tail & head light that also have a
light sensitive switch, a regulator plus a capacator! This means the
light only turns on at night plus the tail light stays on when I stop
for a few minutes.
My Sanyo came with a large head light that had regular batteries inside
(2 D cells). It was designed to stay on at stops as well. I got this
at sears, a different packaging from what the bike shops were selling
way back then.
Before you go off looking for these no-longer made models, you can mix
and match. You can get the schmidt generator and connect it to any
light. You can add your own regulator. You can do all this with the
bottle generator too.
I would not bother connecting a tail light up to a battery pack or
generator. There are plenty of bright flashing tail lights on the
market that would be better. Get the brightest. Get two! Make sure
they are pointed straight back. They need to be visable by the drunk
drivers 1 block behind you, not another cyclist just 5 feet behind you.
Mount it on your bike where it won't get blocked by your seat bag,
rack pack, panniers, etc. Keeping the tail lights out of the generator
circuit has a big advantage, burn 1 bulb and the rest will go because
of the sudden increase in available power. That would leave you with
no lights....
Light bulbs. Argon, Krypton, etc. That refers to the gas inside the
bulb. Krypton bulbs are brighter for the same power than the old
fashioned bulbs. New kid on the market are LED headlights. Okay for
being seen but not great for lighting up the road way.
Beam pattern has nothing to do with the power source. It's all about
the shape and material of the reflector and lens. LED head lights are
typically several leds so its nearly impossible to focus their output
into a beam. I think Bicycling magazine did a beam pattern comparison
a few years ago.
Night riding means different lighting equipment depending on
circumstances. A standard white reflector on the front of the bike
will reflect more light from an oncoming car beam than just about any
bike head light. if you are riding in front of a car, you are nearly
invisable compared to that car's head lights, to oncoming traffic.
This is a circumstance where a reflector is best. In town riding with
lots of ambiant light means your head lights need to be extra bright to
let you see the potholes. Ambiant light dialates your eyes making it
harder to see in the dark. Reflectors in the wheels can't be seen from
behind but can be seen well just before you get broadsided. Reflectors
on helmets are totally useless. Cars approaching from behind typically
have their low beams on which are pointed slightly downwards. Pedal
reflectors are going to be seen first if your feet aren't too big or
your seat isn't too low forcing your heals to block the line of sight
to the reflectors. Of course reflectors don't let you see, but let you
be seen which is very important.
My wife organizes night rides a couple of time every year and I get to
see first hand how bad most bike lighting equipment is, how bad you can
install it, and how the riders think their stuff is great. A tail
light cliped to a jersey pocket is the worst. Not the least bit
visable when you are on the bike and the rider thinks he has some sort
of warning device. A tail light blocked by a seat bag is useless. A
tail light pointed up just 10 degrees won't be seen from very far away.
I personally think flashing tail lights don't show up as well as a
steady light. But do both!
I'm testing out a semi truck trailer tail light. 27 LEDs powered by 6
AA batteries. This is brighter than any commercial bike tail light.
$30 total. The main problem is it's so big, it's hard to fit on a
bike. 5-6" in diameter! I see you can now get LED tail lights for
regular car tail lights. These would be easier to install on a bike
since they are designed to fit in a small place.
Rick
