When The NERDS filled out the Scrapheap Challenge applications, it asked each of us to name a "Passion". My answer was an instant and obvious one - Bicycles. I am a cycling advocate, educator, commuter, and tourist. I even build my own bikes, and fix the bikes of strangers.
With the collection of bike specific tools that resulted, and with my love of fixing things, I started working the bike repair crew for various multi-day sponsored (charity) rides. As a mechanic, I can make a very significant contribution, without having to nag co-workers for donations. I have been a part of the bike tech crew for 4 of the 5 (to date) Boston to New York AIDS rides (the last two as road crew manager - see essays BNYAR 2, BNYAR 3, BNYAR 4, BNYAR 5), and the last 4 Pan-Mass Challenge rides (raises money for cancer research). With some rides hosting 3500+ riders, you see all manner of bike and some truly impressive problems. I have made repairs to literally every part on a bicycle, including mending broken frames. Repairs are sometimes improvised; we don't always have an exact replacement part. Duct tape and baling wire are valid repair parts.
As a cycle commuter, the "special" driving styles of the local motorists and the occasional underinformed police officer turned me into a cycling advocate "in self defense". (One officer issued me a ticket for cycling legally, another threatened me with arrest if I didn't immediately cease legal use of the road, and make illegal use of the sidepath). This led to participation in a number of bicycle advocacy organizations. ( Massbike, Cycling Life) Interest in learning the safest way to use my bicycle led to John Forester's writings, the research summaries of John Franklin and eventually instructor certification in the Effective Cycling (tm) program (I am number 709)
Ten years ago, overuse injuries to my hands forced me off conventional bicycles, and onto a recumbent. No, these aren't some new invention, I have 115 year old pictures of a bike of this type. Those of us that ride them wonder why people ride conventional bikes. Yes, we still have to pedal, but our position is otherwise far more comfortable. When I ride, I sit on something wider than I am, and have a rest for my back. My arms support no weight, and I don't have to crane my neck to see where I am going. Should I hit something, it will be with my feet, not my head, and if I am knocked over, I won't have as far to fall, and I will land on a well padded part of my anatomy.
Many recumbent designs have an aerodynamic
advantage over the conventional "safety" layout, and it was for that reason
they were declared "not a bicycle" in 1934 by the UCI, the organization
that regulates bicycle racing. Since they weren't eligible for racing,
what little commercial production dried up.
In recent years they have undergone a re-birth. Starting in the late 60's with a competition sponsored by Dr. David G. Wilson at MIT, and experiments in streamlining carried out at some California universities by Chester Kyle and students, the International Human Powered Vehicle Association ( IHPVA) was formed to foster competition, and several companies were started to produce bicycles.
Interest in speed competition was encouraged with the establishment of an award fund, the Kremer prize for the first solely human powered vehicle to exceed 65 mph. It was captured in 1986 by Eddy Markham in the "Gold Rush". The bike is now on display on the first floor of the Smithsonian Museum of American History. (Kremer also sponsored several prizes for human powered aircraft).
Current speed efforts have been focussed
on longer distances, with a recent attempt resulting in a single rider
traveling slightly over 50 miles in one hour. There is now a prize, the
- MacCready Hour record prize, for the
first cyclist to exceed 90 km traveled in one hour. Further
assaults on the top speed record (now at 110 km/h, by Chris Huber on the
are expected since the establishment of the .deciMach
prize for the first to go one tenth
the speed of sound (75 mph).
The recumbent community has a number of people that have designed and built their own bicycles. It didn't take me that long to move from updating the drivetrain of my commercially produced bike, to making changes to the frame of a commercially produced machine, and then to CAD software, studying bicycle geometry, and ordering thin wall CrMo tubing. I have built several bikes (all for my own use), and have several others at various stages of completion (from nearly ready for the first test ride, to "the steel is cut", and a couple still just sketches).
Here are pictures of two that get ridden
regularly. One is almost done, the other is by my definition, actually
finished. (to some, a homebuilt can't be considered truly "done",
till you have scavenged at least half the parts from it to attach to a
successor. My personal standard, is that any bike that gets painted
is to be defined as finished. Since I pay others to paint my bikes,
I will ride a bike unpainted for up to a year to work thru all the inevitable
design changes. I want to be certain that I don't need to take the torch
to it any further.) A further note: Frankenbike was rebuilt
since the pictures were taken, and many of the controls and parts have
changed. (it is an experiment after all)
started with a commercial long wheelbase recumbent, but since then I have
built my own. Curiosity about steering geometry led to Frankenbike.
A study was done with a bicycle constructed with an adjustable head tube
and fork. The results were published in the proceedings of the second velomobile
conference. One surprising choice was essentially the reverse of
normal practice. The head tube points forward, and the fork has negative
offset. The testers found it pleasant, and it is surprising that
nobody produces a commercial version. Since I couldn't buy one, I
ordered some alloy steel tube, and built a frame. Here is an early
version, before painting. (For once, under construction refers to
the subject rather than the web page).
Having built a frame, like a good Scrapheap competitor, I reached into my pile of scavenged parts to complete the bike. The mix of parts is rather eclectic, and has changed since this picture was taken. In fact, the variety of parts and parts sources is how it earned its name. The boom and bottom bracket are salvaged from a dead Cannondale. They are kept from rotating by a bit of keyway brazed to the underside of the frame tube, and clamped by an industrial shaft collar. The cranks are road touring; the bottom bracket itself is a MTB unit. The head tube is at an angle of 92 degrees, and the fork is raked 7 cm to the rear. That in combination with a 37-349 tire (one of the "16 inch" sizes) yields a very conventional 6 cm of trail. The piece below the bottom bracket is the original seat tube; it will be used to mount a fairing in the future. The rest of the frame is made from 4130 aircraft spec CrMo tubing, and is fillet brazed.
When the picture was taken, the bike
was fitted with road style brakes, fitted to the rear of the fork so the
chain wouldn't hit the cable. It now has "self energizing" cantilever
brakes. The bars are under the seat, and are connected by a carbon
fiber tube that was intended to be the shaft of a golf club. (I found a
shaft blank, and couldn't resist the look). A grooved skateboard
wheel routes the chain around the wheel, and away from the seat.
Unusual part utilization continues. The seat is a standard unit made by RANS; the seat bracket includes a ordinary door hinge. The rear chain stays are actually front fork blades. The rear derailer shows an extended cage to deal with very wide range gearing. The rear wheel, while built on a road hub, is MTB (559) sized. Continuing with unusual placement, the rear brake is mounted below the chainstays. A pair of clip pins allows the angle of the seat to be adjusted.
The layout with two front and one rear wheel is called "tadpole". (Two rear wheels and one front is called "delta", and if you have two wheels in line, with the third on the other side of the seat, you have a "Coventry"). The two front wheels, using Ackerman steering, result in excellent stability and great handling. The single driven wheel eliminates the need for a differential, greatly simplifying the drive system. Primary braking is by independently controlled disk brakes on the front wheels. The rear wheel has a caliper brake, which is operated by the stoker, using a ratcheting control in the handlebar. Its primary use is as a parking brake, but it is also useful as a "parental override" when a child is at the controls.
The largest departure from the Greenspeed design was in the drivetrain. With a 20 inch back wheel, normal components would yield gearing that was too low to be useful. Fixing it would require either very large (and hard to shift) front chainrings, use of a planetary hub/derailer cluster combination gearing rig (used in the commercial version), or the solution I picked, a countershaft or jackshaft.
The gears on the crankarms have 10 more
teeth than the ones on the countershaft. The 20% step up in rpm that
results, lets me use normal bike gearing on my small wheel, with
normal ranged results. The higher chain speed gives lightning fast
shifting. A further benefit of the arrangement is the ease of adjusting
the crank position for different sized stokers. (I even installed
quick release bits on the clamp, so it doesn't require tools to adjust,
just a different sized loop of chain. I am planning on a tensioning
arrangement so I don't need to swap chains, but I am holding off, as I
would like to replace the chain with synchronous belts.)