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Notes from the Bikelab

Issue #6 -- 1/30/91

by Steven K. Roberts

Copyright (C) 2000 by Steven K. Roberts. All Rights Reserved.

Random Commentary on Matters Various
Handlebar keyboard
Seat fabric
Mobile R&D Lab
More on security
One last solar charging tweak
Wiring harness update
The emailbag
CD packaging

" we enjoy great advantages from the inventions of others,
we should be glad of an opportunity to serve others by any
invention of our own, and this we should do freely and

-- Benjamin Franklin, upon refusing a patent offered
by the governor of Pennsylvania for his stove.

Random Commentary on Matters Various

This is an intense time. Overload is a common theme: the
bike, that perennial focus of attention supported by
sponsorship and publicity, sits mostly idle while I work full
time on sponsorship and publicity. It is a terrible thing to
be finite. Progress is occurring on many fronts, but only a
few of them result in physical changes to the machine.

Some of those fronts are pretty interesting, though... and in
this report I want to bring you up to date on a variety of


First, you may recall from issue 3 the mail discussion about
steering. The question there was whether to stick with the
straight bar under the seat or go to a much more elaborate (and
comfortable, probably) assembly that would be more like tank
controls -- with an articulated linkage of shafts and bell
cranks to couple arm motion to a pair of opposing push rods.
The primary motive was ergonomic, eliminating all twists of the
wrists while adding more handgrip real estate for controls, and
it also offered elevated WQ (Weirdness Quotient) at no extra

After having nighmares about the dynamics of emergency braking
on bumpy roads and other risky situations, we're now back to a
simpler system. Dave Berkstresser has completed the mechanical
design, and the aluminum stock and necessary end mills are in
house. Basically, this is an extension of the original
under-seat steering... but done right. Handgrips will be
removable for service, and mount into the tube with expansion
bolts such that they form about a 45-degree angle with the
frame and tilt up slightly. This should eliminate all
pronation and wrist tension, which have slowed my handlebar
typing in the past. A pair of 1616 bearings embedded in the
pivot assembly should make the whole thing tight and smooth,
and actuation of the fork will be via half-inch stainless
tubing and rod ends as before.


I still haven't figured out quite how to mold the handgrips,
but there's one major bit of progress in that department: the
"switches." In the past, I used a variety of pushbuttons,
rejecting the C&K's for environmental flakiness, trying and
discarding a few surplus things, and eventually settling on the
ON buttons used by Hand Held Products in the Microwand (the
Fed-X bar code scanner). These worked pretty well, and were

What I really need, however, is a software-definable switch. I
want to have some hysteresis... but I don't yet know how much.
I want to have actuation force adjustable to taste. I'd like
to be able to experiment with using one for Morse Code (yes, I
know the computer can do that, but it's fun). And since the
bike now has a MIDI system, I need to emulate the flute... but
I'd like aftertouch information to make it more expressive.

This is a lot to ask of a pushbutton switch. But there is a
solution: Force-sensing resistors (FSRs) from Interlink
(805-684-2100, Bill Yates). Originally developed for music
keyboards, these are made of two flat polymer sheets with
interdigitating electrodes on one surface and some kind of
"semiconductive" material on the other. The harder you press,
the lower the resistance. They come in a variety of sizes, and
the product line includes linear potentiometers and XYZ

The ones for the bike are about a half-inch square (with an
active area that's half that), and will be bonded to the
fingertip lands on the molded grip assembly, covered with a
rubber keycap with just enough mechanical hysteresis to provide
light tactile feedback. A scanning A-D converter under control
of one of the New Micros 68HC11 boards (or, possibly, a local
PIC processor from Microchip) will monitor the resistances of
all ten FSRs and pass the information on to the keyboard
software. Depending on the application, this will yield a
character, a macro, a musical note, or anything else that may
be relevant. (A friend suggested using the aftertouch
information to add emphasis... squeeze hard to capitalize!)
The nice thing about the whole approach is that it puts large
unknowns into the TBDWL (To Be Dealt With Later) box (otherwise
known as software).

More on that -- and on the new chording scheme -- another time.


A new seat panel has arrived, custom-sewn of black nylon mesh
(Luna-mesh) by someone in Boston. This has provision for the
insertion of aluminum rods on both sides, which are then
grabbed by about 50 cable ties to the aluminum seat frame.
This method is cheap, easy to install, and quite pleasing to
the eye. And the cable ties, which can take 120 pounds each,
are very reliable... IF black ones are used. White ones
degrade and fail from UV exposure within weeks. I'm using
Panduit this time around... tensioning them properly with a
hand-operated GS4H installation tool. (Panduit makes
everything for wiring)


This will be the subject of a whole article someday, but I've
gotten some questions lately about what test equipment I
carry... and the recent addition of a Fluke 87 Digital
Multimeter provides the news hook. A soft pack will contain
the Createc 10 MHz digital oscilloscope, the Fluke, a logic
probe, a spectrum probe, Ultratorch butane soldering iron,
wiring tools, and a large tinkering stock of chips and other
components. Since I'm going to soft logic as much as possible,
I also carry a BP Microsystems device programmer, a Datarase II
miniature EPROM eraser, development tools for the Microchip PIC
processors, and as much documentation on microfiche and CDROM
as possible. The hardware toolkit is not yet together, but
includes a Makita battery-powered electric drill (with 12-volt
charger) and a full suite of hand tools. Unfortunately, Cecil
has to remain behind... no room for a 900-pound milling
machine on the bike.

This new meter is remarkable. Accustomed to the DMMs of
yesteryear that measure AC/DC voltage and current, along with
resistance, I was hardly prepared for the range of measurement
tools built into one small rugged instrument. The 4-1/2 digit
Fluke 87 has an analog bar graph, performs min/max/average
recording up to 36 hours, measures frequency and duty cycle,
determines the forward drop of semiconductor junctions,
measures capacitors, will display readings relative to a stored
reading, and has ranges for all the essential measurements that
almost defy comprehension (in conductance mode, for example,
you can measure up to 100,000 megohms). Seriously neat stuff.
It's about 10 times the size of the teensy Soar meter I was
planning to take, but has hundreds of times the capability.
Hey, it's only gravity...


In issue #1 of this series, I mentioned the Alpha microwave
motion sensor, which is integrated into the support column for
the big yellow flasher. That is the "level 1" alert,
indicating that someone is within about 10 feet of BEHEMOTH.
Other components are now coming together as well.

The "level 2" alert is provided by the UNGO Box, made by Techne
Electronics of Palo Alto. They did something
unusual for an automotive product: designed it for extremely
low-power operation (I wish car stereo manufacturers would do
that). This surface-mount board accepts inputs from two motion
sensors -- remarkable little units that were well proven during
6,000 miles on the Winnebiko II.

Essentially, each sensor is a blob of mercury with a 40 kHz
field around it. Any rippling or motion of the mercury yields
changes in flux density, which are then picked off and filtered
by sensitive op amps. A settable threshold level then
determines whether the disturbance is severe enough to issue an

On BEHEMOTH, there is a 130 db siren -- but it is mostly useful
to convince dogs that chasing me is not a good idea (it sweeps
into the ultrasonic and is seriously obnoxious). The typical
response to a motion alert at this level is to speak to the
perpetrator with the synthesizer while beeping me on the pocket
pager (or calling me on ham radio) to let me know someone is
touching the bike. There will be much more on the psychology
of BEHEMOTH-protection in a later issue... it gets quite

The "level 3" security alert indicates that access panels are
being opened or connectors unplugged. (There are now
microswitches on the RUMP and trailer lids, and more will be
installed as enclosures are completed; loopbacks in all harness
connectors provide feedback on unplugging.) Levels 4-6 are not
yet implemented, but are the seat switch, physical movement of
wheels or steering shaft angle, and changes in GPS satellite
navigation coordinates. This last, without corresponding
password, is a major red alert and the bike will attempt to
emulate a 5-alarm fire while taking local steps to make riding


You may recall the ongoing commentary about dark current and
other bugaboos in the power management system -- I took care of
that problem (while adding another potentially confusing
"mode") by installing a Solar Disable switch betwen the charge
manager and the batteries. During long storage away from
daylight, this will reduce the power leakage by 5.6 mA.


Wiring isn't a particularly glamorous part of the system, but
it sure seems to be one of the major time sinks. The harness
was officially begun this week with the installation of an
enclosed aluminum subpanel on the underside of the port
RUMP-bay (about axle-level on the rear wheel, just above the
trailer hitch). This contains a 61-pin military-style Bendix
connector for data, a Lemo waterproof RF connector for a remote
antenna, and a 4-pin automotive trailer connector for the power
bus. In addition, there is a rubber-booted toggle switch that
rearranges the relationship between local battery and load when
the trailer is disconnected (with trailer, all batteries are
effectively paralleled and managed as a group; without, I
bypass all that).

This subpanel is gooped onto the fiberglass, and a plastic box
is mounted over it to keep stray DRAMs or tools from falling
into the pins.

"Those are the headlines -- now the rumors behind the news..."

The Emailbag

The article on Poor Man's Composites in issue #4 generated considerable
mail, as expected. Frank Lyon, via the Well, suggested some additional
local sources for materials:

I really enjoyed your tale of fiberglass fabrication. I've
built five windsurfers in the last 5 years starting from a
state of pure ignorance so I've 'been there.' Cardboard sounds
like a good low-hitec solution!

Let me pass on a few resource tips:

You should check out Monterey Bay Fiberglass in Santa Cruz.
They have a complete stock of materials
including the exotic Kevlar and graphite, and thay can give
good advice.

Also check Clark Foam. Besides being THE maker
of surfboard blanks, thay make block and sheet foam, the
hi-hitec way to do what you did. And their tech literature is
ADDITIVES AND MATERIALS GUIDE for some good bedtime reading :-)

Kevlar has the best impact resistance and toughness of any
fiber. You should talk to HEXCEL in Dublin, CA.
They weave fabrics like S-Glass, Kevlar & Graphite so thay are
a primary resource.

Good luck with your projects!

In response to the piece in issue #5 where I sketched an on-the-road
scenario of life with BEHEMOTH, Ken Okin here at Sun offered a succinct

Paradise for the techno-weenie!!!!!

Ken's got me pegged.

And Duncan Elliott from the EE Dept at the University of Toronto asks:

What kind of trailer brakes do you use? How do they couple at
the hitch? When you're going down hill and using the
regenerative braking on the front wheel, are you in danger of


The trailer brakes are not yet implemented... awaiting tests on
the Mathausers. The plan is to tie them together at a surge
linkage in the hitch, unless I can find a safe way to store
brake-compression energy (not in batteries... they can fail).
Jacknifing does not seem to be a problem -- I've had the
bike-trailer combo up to 50.5, and that was with bike brakes
only. Of course, they were really lousy brakes.......

CD Packaging

Music is essential. During the first trip, I carried an Aiwa
cassette deck and later a Sony, plugging earphones into my head
and listening to the same old 12 tapes over and over and over
(at least when local FM had little to offer). Occasionally I
would stay with someone who had a good stereo, and I could
record over a tape that had become particularly boring.

On the second trip, it was the same basic problem, though I did
double the size of my music library. Still, it was a pain: I
had to go into "music mode" to listen to something, blocking my
perception of other audio sources (including reality) with ear
inserts and having to stop the bike to change tapes.

Considering the motivational value of music, I've decided to do
it right. BEHEMOTH now has a Sony automotive stereo system
with AM/FM, cassette, and shock-mounted D-180K CD player.
There's a pair of 4" Blaupunkt speakers on the RUMP just behind
my shoulders. Headphones can be used as an option, but are not
necessary. And MIDI, video, Mac Recorder, cellular phone, ham
radio, speech synthesis, and other audio sources can all be
mixed under software control with the entertainment audio -- so
I'm no longer stuck in a mode that cuts me off from
communication and survival data whenever I need some jams.

All of which will be discussed in more detail later, but
there's one problem that concerned me right up front: having a
good stereo makes one wish for a good music library, and those
are bulky. How many CDs in jewel boxes would I be able to
carry? 20, maybe?

The solution is elegant, and anyone interested in portable CD
use (or software distribution) should check this out. A
company in Dublin, Ohio called Univenture produces a product
called the CD-Viewpak. It is a soft clear vinyl sleeve, into
which is bonded a layer of spunwoven polyester much like the
liner material in a floppy disk. This protects the active
surface of the CD while leaving the printed side visible -- and
the space behind the liner allows room for the insert
describing the disk (to save weight and space, I just photocopy
the cover page and leave the booklets and jewel boxes back at
the base office). My current library of 40 disks has been
compressed from 16" of shelf space to 3" in the pack.

Using a Cannondale racktop pack as an enclosure, the
CD-Viewpaks will allow me to carry between 100 and 120 disks on
the bike. The weight is approximately 1/7 that of jewel
boxes. Univenture offers a number of variations on this
theme: the packs alone, wallets of 12, boxes of 70, or binder
systems for shelf storage of a music library (or inexpensively
shipping CDROMs with documentation).

Closing Notes

That's it for this issue. As you may have noticed, I missed a
week: I've been in a state of serious overload setting up the
new business structure, trying to get issue 10 of Nomadness
written, negotiating deals, seeking goodies, and -- oh yes --
working on the bike. I did take a much-needed break for a
camping trip to Pinnacles National Monument, and was reminded
while clambering over world-class vastness that somewhere under
all this techno-gizmology are some very deep-rooted motives for
travel. Oh yeah... I remember... As the countdown progresses
(24 weeks), this becomes critically important. It goes way
beyond mere motivation and project management -- this takes
unwavering passion and obsession...

Both of which weaken under fluorescent light.

Cheers from another Sunday in the bikelab!