Tron Bike: Clear Plastic Bike With LED Edge Lighting

Tron bike: it's a 100% clear plastic bike frame with LED edge lighting. The entire frame starts from a single flat sheet of clear polycarbonate (lexan) plastic which is cut into pieces and assembled. LED edge lighting is added to provide great night-time special effects. The bike falls a bit more on the "art" side than the "practical" side as it is heavy and wobbly, but it is rideable and great for cruising town around at night.

The original (un-lit) clear plastic frame concept & design is by saul, who led an intersession class at the MIT Media Lab in 2003 (?) where about 10 students each designed and built a clear plastic bicycle frame. Some of the students modified the frame styling a bit, one of the other frames with a more curvy style is shown below.

After seeing one of the frames around MIT in 2004, I had the idea for customized edge lighting so I built up a frame and added the lighting effects.

The full project here is quite a lot of work unless you have a high-end machine shop at your disposal, but there should be several ideas for you along the way. I've included the CAD files for the plastic frame and the C code for the microcontroller. This is an "after the fact" documentation, i built this about 3 years ago.

As seen in the Wired Blog.  

This article is brought to you by MonkeyLectric and the Monkey Light bike light

Step 1: Tools & Parts You Need

plastic frame:

- a 4' x 8' sheet of 3/8" thick clear polycarbonate
- a 2' x 4' sheet of 1/8" thick clear polycarbonate
- a 2' long, 1" diameter clear polycarbonate rod (handlebar)
- acrylic solvent cement

bike build:

- standard bottom bracket
- standard seatpost & seat
- 26" rear wheel with coaster brake
- 26" front wheel
- threadless headset
- 12" long aluminum fork tube (sized for your headset diameter)
- standard stem
- standard crank arms & pedals

LED edge lighting:

- as many LEDs as you desire (this one has about 200 x 5mm leds, but you probably want to use high-power leds)
- 22 guage wire in 4 colors
- three copies of my simple constant-current led driver circuit, one for each bank of LEDs
- simple Atmel AVR controller circuit which drives three FET's, each fet turns on/off one of the LED banks.

Tools:

You need to be able to cleanly cut out the plastic frame parts from the sheet of plastic. You might be able to do this with a jigsaw, a dremel tool and a lot of patience, otherwise you'll need a CNC mill or a CNC waterjet cutter.

You will need a bottom bracket tap to cut the threads into the plastic to screw in the bottom bracket, most bike shops probably don't have one of these and you'll have to try a custom frame builder.

A dremel tool to polish any of the plastic edges that don't quite fit.

standard bike tools

soldering iron & pcb assembly gear

Step 2: Cut the Frame Parts!

i've attached a cad file with all the parts needed for the plastic frame.

I ADVISE BEEFING UP THE BOTTOM BRACKET AND REAR WHEEL DROPOUTS BEFORE CUTTING YOUR PARTS. by this i mean: add some extra plastic around the bottom bracket and rear wheel dropout areas as compared to what is shown in the cad files. These two areas failed on my bike, i had to repair them afterwards.

you can also re-draw the outlines of the frame for a custom shape.

Step 3: Frame Assembly

the entire frame fits together using tongue-and-groove assembly, after it is assembled use solvent cement on all the joints. if the fit is very tight use a file or dremel to help, and a hammer. the fork is assembled separately from the frame. there are not so many parts so it should be pretty clear how it all fits together.

i'll highlight a few key areas in the next steps

Step 4: Bottom Bracket

my bottom bracket broke - you should increase the diameter of yours so there is more plastic supporting it. after mine broke i added fiberglass around it, so yours will be a lot neater than what's shown here.

Step 5: Headset & Front Fork

the front fork is assembled separately from the headset & main frame, just like a regular bike.

first assemble the main frame, then install the standard threadless headset bearings into the plastic head.

assemble the fork, then install the fork tube into the plastic, and then attach fork to bike in the usual way.

Step 6: Seat Clamp & Rear Fork & Rear Dropouts

the seat clamp is tightened using the two bolts.

you can see my rear dropouts are reinforced by gluing some extra plastic to make it thicker.

Step 7: The Electrical Circuit & Programming (overview)

I used a very simple circuit here. the LED's are in 3 banks. each bank is all one color of led (one bank is red, one is green, one is blue). all the LED's in a bank are wired in parallel. each bank uses my simple LED constant current source. each bank can be turned on or off using a power mosfet. lastly there is an Atmel AVR microcontroller which turns the 3 mosfets on and off in a few simple patterns, i've attached the C code for the microcontroller.

there are two simple patterns currently programmed:
1) blinking the 3 banks. this is a very epilepsy-inducing pattern, it blinks each bank for 1/7 of a second, in a cycle.

2) color fading. using PWM, it fades each color in and out in a cycle, the same pattern you now see in innumerable chinese 10 cent blinky toys.

Step 8: Adding the Edge Lighting

having all the led's of a single color in parallel dramatically simplifies the wiring job. there are 4 colors of wire routed all over the bike: black (ground), red (red led positive), green (green led positive), and blue (blue led positive).

I used about 200 x 5mm leds for this project, back when i did it high power led's (eg Luxeon) were very expensive. if i did something like this again i would most likely use Luxeons, it would save a lot of work on the lighting install and light up the bike just as well. it wouldn't look quite the same since it would be fewer points of light, but probably just as good anyway.

install leds like this:
- drill a hole deep enough for the led into the plastic
- jam in the led
- bend over the led leads against the frame
- strip a small area off the two wires - it is very convenient here if you have a stripping tool that does not cut the wire
- solder the two wires to the led leads
- coat everything with hot-melt glue or silicone

covering everything with glue made the wiring a lot faster since no tape or shrink-tube is needed. on the downside you can see that the glue job is a big ugly mess.

you can go back and look at all the photos to see how i just routed the 4 wires all over the frame and drilled the leds everywhere.

Step 9: Wiring the Front Fork

to protect the wiring to the fork from ripping out, i added two strong cables which limit the steering angle

Step 10: Circuit Attachment

all the circuit controller stuff is just glued into the middle, and there is a battery pack holder (it runs on 4 x NiMH AA batteries, or plugs into the wall using a 5V 2A wall wart)

Step 11: Other Ideas

the construction method for the lighting was quick-n-dirty, and it made a big mess of the frame which looked a lot nicer before all the wires and glue were stuck on. just doing the wiring neater would help, and making it all one color wires would look better i think, and keeping the glue much more contained.

on a different one of these frames i saw, the plastic edges were all polished mirror-smooth (just like they do on eyeglass lenses sometimes), this is not too hard with a power polishing wheel and looks nice.

it would be great to have a more sophisticated lighting effect, but that would require a lot more wires to get individual control of the leds. the leds i used were from about 2001, new power led's would be a lot brighter and require a lot fewer leds and less wiring.