Light testing

I Finally got a hole made in the bottom of my stainless steel cup that will make the body of my light. So I have gerry rigged it for some beam testing. The lens wedges in at about 30mm down the cup, so I wanted to test the beam I got from the lens wedged in and the lens mounted right at the mouth of the cup. A narrower bright spot would mean better range. Here are the results:

• No lens: Bright spot only 30 cm wide with extreme light diffusions and bleed out to about a 1.5 m circle


• Lens wedged in 30 mm from mouth of cup: Bright spot about 90 cm in diameter with a less bright ring about 1.5 m


• Lens at mouth of cup: Bright spot about 68 cm.

So it appears that mounting it at the mouth of the cup will be best. I have decided not to attempt to manufacture an end cap for the light. Instead I will drill some small holes and screw 3 or 4 short, self-tapping screws through these holes for the lens to rest on. Then I will seal the lens to the cup with a bead of silicone. This way I can cut this away to replace a damaged lens or install a better one without too much trouble.

Here is a photo of the temporary setup:

Project Headlight

Well as promised, here is my first post on my new project; Project Headlight.

With the speeds that I go at, I feel the need for a better headlight. Especially during the last couple of km before I get home at night. It is virtually pitch black, downhill (AKA quick) and there are people walking on the bike path, including those with dogs off lead. My current headlight gives me about 10 metres of very feeble light. Some quick calculations tell me that at 35 kph I am going about 9.72 metres/second, so my current headlight gives me about 1 second to react to anything on the path. I need something better.

From the beginning of this project I wanted to make myself a decent headlight. To buy these cost ~$300 for something decent. Surely I could make something almost as good for a fraction of the cost. My research led (no pun intended) to believe that Luxeon Star LEDs were the way to go (I have since learned that these are being dropped in favour of CREE LEDs). These deliver about 100 lumens of light (a 100 watt incandescent light is about 1,700 lumens). I looked around for people who had documented their projects and this is what I found:

1. This one is pretty good, but a bit bodgy.
2. This one is good but complicated looking
3. This one is also a little complicated, but seriously impressive

I decided to go for design number 3 due to the addition of the lens on the front amplifying the number of lumens to 500. It was also featured in Silicon Chip magazine along with the driver kit it employs. You can't just hook a LED up to a battery if you want it to last. It needs some sort of current limiting device. This is because a LED is a diode and a diode is just a component that lets current flow in one direction and not the other. If you overdrive your LED it will melt. You can simply put a resistor in line to limit the current, but the resistor I would need for this 5W LED would be a 10W resistor, which would then bleed twice the power I am using for light to heat. This driver kit supplies a constant current so will give me the 5,000+ hours of life the data sheet on the LED reckons it should get. It will also drop down the current from my battery to the voltage required by the LED serving a dual purpose.

Off to start looking for materials. I was lucky enough to find someone in Canberra selling off two 5W Luxeon Stars (Jaycar has now discontinued these. Probably due to the $69 RRP price tag) and two collimators (reflecting housings) on eBay which I won for $48. Bring in my friend Peter who has a Phd in Electronic Engineering (robotics) to build the switch mode power supply driver kit for me. He modified this to run at the ~40V supplied by my main battery instead of the normal 12V it expects.

I now have all the major components and need to build mount and test the light. Here are some photos:

All hooked up to my battery, ready to go


The LED mounted on a former Pentium III heatsink


The LED with the collimator on top


A close up photo of the driver board

Idiots in cars who hate people on bikes

From the ABC News web site:

A man has been charged over a crash involving a group of elite cyclists, including Olympian Ben Kersten, in Sydney's south last week.

About 50 cyclists were riding along Southern Cross Drive at Botany last Thursday morning when they crashed into a car.

Among the group was Kate Nichols, who was injured in the 2005 accident that killed fellow rider Amy Gillett.

Kersten claimed the driver overtook them and then stopped suddenly, causing the lead riders to hit the car, before driving off.

No-one was seriously hurt but some cyclists had to be treated for cuts and bruises.

The 34-year-old Claymore man has been charged with failing to stop at a crash and give particulars.

He will face Waverley Local Court next month.

Police say they are still investigating the crash.

OT - Dumb things

This is my first off-topic post. So if you are after some story about my latest trials, then you can close your browser now.

I was reading an article about the comparative longevity of more and less intelligent fruit flies in this week's New Scientist and a phrase in the article struck me: "Brainier flies live shorter lives than dumb ones."

Now there is a phrase in plain English that I admire. Honest and to the point. There are brainier flies and there are dumb flies. When was the last time you heard someone, especially someone in the public eye, refer a human's intelligence level in this way? Why are terms like dumb so imbued with negativity that we have to use new descriptions like "less intelligent". When does that label take on the tarnish of "dumb"? Will we have to start saying "differently intelligent"?

You may argue that the social stigma and taboo on such terms comes from their common use in an insulting manner so that they have been robbed of their original context to such a degree that they can no longer be used as a simple, honest (if subjective) description.

I think it is time we started judging the intent, not just the content of what people say, don't you?

Project 2-speed is complete

A few weeks ago I blogged about getting a single speed free wheel on the back wheel of my bike and how I needed a bigger crankset on the front to maintain a decent speed without sprinting. Well this work is now complete and I have three rides under my belt on this setup. I also had comfy soft-touch bar ends installed to compliment my new grips as well as an interim headlight to prevent further crashes (more on this in future posts, lets call it "Project Headlight"). The final part of this purchase was the new seat I needed after crashing.

The speed I am now maintaining is only 1-2 kph faster than before, but I can keep it up for much longer. Before I used to have to pedal quite fast to get to 38 kph on a flat and then I would have to rest, then go again. Now it is achievable with a much mor comfortable cadence.



Here is a picture of the bike:


Here is picture of the new drive train:




Here is a photo of the handlebar setup. It is pretty crowded now. Note the rubber band around the thumb throttle. This is my "cruise control".



Here is a better photo of the "cruise control". You might think that it will interfere with the gear changer, but this is defunct now since I only have one gear on the back.