On 2/24/2018 7:10 PM, Jeff Liebermann wrote:

Opinions vary:
- Frank wants brightness limited to avoid blinding oncoming motorists.
- SMS wants some upwards spill to help see overhanging branches.
- You seem to want (not sure) more beamwidth to help see the roadside.
- NASA wants even lighting and no hot spot so that press release
photos look good.
- Barry wants only the forward facing area to be considered (beam
lumens), discarding the dim spillage as useless light.
- I want megalumens so I can set fire to the riders clothes ahead of
me. I also want megalumens because my principle use is "be seen"
lighting, which means I want to get the attention of motorists.

That's not an accurate collection:

- Frank's main concern is that the light work off a dynamo. All his
other statements are rationalizations of why it is not necessary to
illuminate anything other than the pavement immediately in front of a
rather slow-moving rider. He understands, but does not want to admit,
the importance of proper optics on LED lights in order to illuminate not
only the patch of pavement directly in front of the tire.

- I want both side spill and upward spill. But of course you can do this
without blinding oncoming motorists, which is a red-herring anyway since
on even a two lane road, with the cyclist on the right (or on the left
in countries where they drive on the wrong side of the road), a motorist
coming the other way will not be blinded. The real concern is that on a
narrow MUP that oncoming cyclists not be blinded.

- More beam width is also a side effect of a proper beam shape.

- Barry's emphasis on NASA is unhelpful in marketing bicycle lights. His
lights do have some real advantages in terms of optics and batteries,
and if they were priced at $100 and $200 I think he'd be selling a lot
more of them. It's really hard to work with bicycle shops that demand
Keystone margins, and even harder if you have to go through distribution.

- Your desire to set fire to the clothes of riders in front of you will
not be achieved by LED lights. You could use a flame thrower, but to
achieve sufficient range would require a very heavy and cumbersome
system. You might look into laser modules, i.e.
https://www.amazon.com/dp/B071HB9LX5. Since you'd not need it to run
for long periods of time, you could run it off of a 4S Li-Ion battery pack.

- Jay's main concern is that whatever light he buy be on the bargain
table at one of Portland's famous bicycle shops.

- Joerg's main concern is that the light and battery can pass his
vibration tests.