The XR2 is an extremely sophisticated machine. It is as efficient a vehicle design as I have ever seen, aside from Bruce Bursford's Ultimate Bike. This means that it can be totally unforgiving if built wrong. I'm not saying that it would kill you; it just might not function if you build it too funkily. For example, relocating the forward bottom bracket an inch or so forward would mean that you might not be able to steer or pedal the thing. Mr. Riley covers all that sort of considerations in his very comprehensive technical notes. People who need more or less leg room than the range of the adjustable seat position are told exactly where to stretch or shorten the frame. The unmodified frame can accommodate riders from 5'3" to 5'11", so most people shouldn't need to change anything about it.
Building your own carbon-fiber recumbent bike may seem like an outlandish undertaking, unless you're Damon Rinard, or one of the IHPVA crowd. Or maybe, me. However, after intense study of Robert Q. Riley's plan-set for the Ground Hugger XR2, I can confidently state that you probably can, if you really want to do it. It might be useful if you were the home-handyperson type, but Mr. Riley has designed his instructions under the assumption that you are a total nimrod at this type of thing. Being a nimrod might even be a benefit, as people who start out with a developed skill-set might be inclined to not follow the directions as slavishly as they should. A little learning is a dangerous thing for this sort of project.
BikeRod&Kustom Review:
Robert Q. Riley's
Ground Hugger XR2
Carbon Fiber Recumbent
Build-It-Yourself Plan-Sets

By Jim Wilson,
BR&K Editor-In-Chief
Building your own carbon-fiber recumbent bike may seem like an outlandish undertaking, unless you're Damon Rinard, or one of the IHPVA crowd. Or maybe, me. However, after intense study of Robert Q. Riley's plan-set for the Ground Hugger XR2, I can confidently state that you probably can, if you really want to do it. It might be useful if you were the home-handyperson type, but Mr. Riley has designed his instructions under the assumption that you are a total nimrod at this type of thing. Being a nimrod might even be a benefit, as people who start out with a developed skill-set might be inclined to not follow the directions as slavishly as they should. A little learning is a dangerous thing for this sort of project.
would be astonishingly light and strong. The same process is used in the construction of high- performance home-built aircraft, which should give you an idea
of the strength and durability of this type of construction. The comparatively small size of a bike frame means that even a rank amateur using this process can make one quickly.
Right: Identical hardboard templates are made using full size patterns. A hacksaw blade is used to cut the foam to shape, with templates on both sides as guides.
machine shop to make the parts yourself. Very few people fall into this category, myself included. This is not a problem, as Mr. Riley, taking that into account, provides the drawings and data for you to take to a machinist. The most difficult part of giving a job to a ma- chinist is providing all the info he needs to do it properly. These plans take care of that.

Right: Rendered 3D models make for extremely good instructional images.
The carbon-composite frame is made using a process Mr. Riley has been perfecting for decades. The basic form is cut and shaped from urethane foam. This form is covered in layers of carbon-fiber cloth pieces saturated in vinylester resin. This composite skin is then smoothed and filled with common auto-body filler (Bondo). It is then painted conventionally. The finished frame
According to Mr. Riley, the materials, parts, and machine services needed to construct the frame will cost in the vicinity of $800. This does not include common bike parts such as wheels, tires, cogs, shifters, cranks, brakes, etc. Mr. Riley recommends stripping a used bike of these parts, as this shopping list can get expensive if you just walk into a bike shop with it. He says 80% of the parts can be obtained from a single used bike, presumably an MTB. I bought an ideal donor bike like that last year at a yard sale. Missing its handlebars, it cost me $20. After you've spent the big bucks and finished your basic XR2, you can take your time about acquiring new, snazzier parts to swap into the machine. Recumbent bikes are inherently more expensive than upright bikes, as they are not mass-produced. It is easily possible to spend several thousand dollars for a high-end model. If you could walk into a bike shop and buy one in carbon fiber composite, it would be even more expensive than that. At a final cost in the neighborhood of a thousand bucks, the XR2 is an astounding bargain.
The XR2 plan-set comes in two flavors. For $75, you get a set of six large plan sheets with full-size patterns where needed, and an instruction manual. For $100 you get that and an amazing
CD ROM formatted for Wintel platforms. The CD contains 3D models, 2D CAD
drawings, an electronic construction manual with large high-rez photos,  links to on-line services,  software for viewing the 2D CAD & 3D models in Windows, and video clips of the XR2 in action.  I'll cover the CD later, but you can certainly build an XR2 using only the $75 package.
Right: Instructions cover the making of a simple fixture to hold rear stays
in proper relationship for welding.
The XR2 is a very modern design. Like other modern technology, it was mostly designed using
computers. A side benefit of this is that the technical images in the instruction manual are rendered
from the actual digital data of the design. In the old days, instructive images would have been drawn by an illustrator working from murky photos or blueprints, with lots of opportunity for confusion to creep in. The XR2 manual benefits greatly from the crystal clarity imparted by computer renderings of 3D digital views.
All images © 2000, Robert Q. Riley Enterprises
Ground Hugger XR2 Deluxe Plan-Set's Electronic Construction Manual CD-ROM
Printable Color
AutoCAD Plan-Sheets:
All the plan-sheets are included as AutoCAD files, so you can have lots of printouts of the full-scale templates. The best way to cut something out is to paste a full-scale pattern to it, then take the saw (or whatever tool) to it. If you screw it up, you print out another one. 
Full-Color Hi-Rez Images
of all the B&W instruction manual images are included. The finer detail and additional color input will make a big difference to a lot of people (Like me and a lot of my other dyslexic friends).

Left: Notice the difference between this hi-rez
color image and the same one in B&W from
the paper construction manual, shown above.
Right: The subtleties of the layers of a carbon composite form are extremely difficult to see
in a B&W photo. Color helps a lot.
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Movies!
If you've ever wondered how you would launch yourself off on an XR2, or any other 'bent, seeing
a movie of someone else doing so, in close-up, is an extremely good way to learn the operation. There are also other movie sequences: all  demonstrating that them-there new-fangled recombinant bio-cycle dinguses actually work.
Right: There is also a '60s-era film clip of the original welded-tubing Groundhugger performing on the road.
(Look, Ma-No Hands!). Not only is the rider, young dare-
devil Robert Q. Riley, not wearing a helmet, but it looks suspiciously like they shot the film on LA's Mulholland
Drive, home of the notorious "Dead Man's Curve".
There were giants in those days!
Plug-Ins, Upgrades, Software:
This disc comes with a lot of content which will benefit from having several other applications on hand to utilize it fully. It comes with version 5.5 of MSIE, Shockwave, Whip! (for AutoCAD Files). etc. This includes Rhino3D, for viewing and modifying actual 3D models of the finished bike. Being able to zoom in on a detail, at whatever viewpoint or level of magnification you prefer, is of tremendous benefit to someone engaged in building a fairly-complicated machine like the XR2. Rhino is a very sophisticated 3D modeler, which goes for about $800, retail. The Rhino3D demo version included with the disc is full-featured, and is good for 25 saves of modified 3D RX2 objects. If you plan ahead sufficiently, you can do quite a bit of Kustom work before using up the saves. In my opinion, Rhino is a really great, powerful, and intuitive 3D modeler, and it's very useful having it available on the XR2 CDROM.
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Rhino 3D and the RX2-3D Model:
Screen save shows the Rhino 3D  workspace. 4-view of complete XR2-3D model is shown. Separate sub-assemblies of the XR2 are also furnished, made up of clusters of 3D parts.
Above and Left: Screen saves of Rhino wireframe close-up and perspective rendering reveal the incredibly accurate detailing of the XR2 3D model.
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In Conclusion,
the XR2 Deluxe Plan-Set is far and away the best package of its type that I've ever seen. The information included will give you anything you need to know to build the bike, and there are, literally, hours, days, and weeks of amusement value included in the package. Robert Q. Riley is to be congratulated not only for the design of the XR2, but also for the design of the excellent instruction-set for the building of it.
PS: Mr. Riley and I finished the main interview before the prototype CD-ROM disc was finished. After reviewing the Deluxe Plan Set, I realized that I had a new set of questions, to do with that aspect of the plan-set. The following short interview covers this topic.
BRK: That's a really interesting film clip of you riding the Ground Hugger downhill, with hands off the steerer. I guess you must have trusted the machine not to kill you. Were you to do that run on the XR2, nowadays, would you be more inclined to wear a helmet?

RQR:  I haven't even considered doing no-hands run on the XR2, with or without a helmet.  Not that it's any less stable than the original Ground Hugger.  But consider that I was only 24-years old when that film was shot, and I was not at all concerned about the possibility of ending up on the pavement at 35 mph.   Since then, I've discovered that I'm not really invincible after all.  That's me riding the XR2 in the other videos, but 25 years later and wearing a helmet.  And speaking of helmets, notice the difference in the total garb. It seemed normal back then to go cycling in dress slacks, a white shirt, and bare-headed.   And I doubt that one in a hundred bike shops would have carried a cycling helmet (who would have wanted one?), and certainly not jerseys and pants.

BRK: I realize that the XR2 3D model's main function is as a visual aid to constructors, and most constructors wouldn't need to make their own chain. However, for playing with the model in my favorite 3D program, I'd like to have chain(s). I zoomed in on a sprocket on the model in Rhino3D and realized that it would be perfectly straightforward in Rhino, to make a pair of rollers, pins, and links, then copy and paste them into the model as many times as it took to fill the chain path.
RQR:  The modeling job for the XR2 was enormous.  One of the biggest differences between modeling for appearance and modeling for engineering purposes is that the engineering model has to include everything, even if it doesn't show on the outside.  Titanic is a good example.  To model the hull for appearance, you would just create the outside skin, and the skin would be made of one piece extending the length of the ship.  But that's not how Titanic was built.  So with an engineering model, you would create each of the metal plates used to make up the skin of the hull.  And each plate would have an inside surface (a thickness to the plates).   Then you'd have to put in the substructure and mechanical parts, right down to the bearings that hold the propeller shafts.  And don't forget the rivets that hold it all together.   So the model would include many times more pieces, and everything would have to be modeled to high degree of accuracy- typically one-thousandth of an inch.
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Left: Rhino 3D may be
used to make Kustom modifications.to the
XR2-3D model. Included AutoCAD software can turn the changes into plan form.
BRK: I forget; but that was an excellent answer.

You've set up a password site for builders who've bought the plan-sets. I've been checking it out,
and noticed that you've announced the future availability of XR2 kits, consisting of the machined
metal parts, and pre-shaped frame foam armature and needed composite materials. That's a brilliant idea. I'm sure it will make the project much less formidable to a lot of potential builders.
Do you have a time-table for availability, and pricing?

RQR:  Kits will happen as soon as we can work out the details. Until now all my time has been devoted to producing the CD-ROM.  Now that the CD is done, a great deal of time has been freed up for other things.  But don't ask me for a date.  I've pretty much given up on the idea of predicting the future. Winston Churchill said: "I much prefer to make predictions after the event
has happened."   So I'm switching over to his technique.
Over the last few years, there's been a total revolution in the way products are designed. Every- thing is done in 3D today, and the technology is just now reaching the point of filtering down to
the consumer level. And when companies like Chrysler use 3D models in their consumer advertisements, it actually promotes the technology itself.  That's why I'm so excited about what we're doing with our plans on CD-ROM.I think we are just a little ahead of the curve in terms of consumer familiarity and comfort with the technology.  But the time is just around the corner when 3D will be commonplace even for the average hobbyist.  And it's more than just 3D modeling. 
It's the whole transition to an electronic format, with the Internet playing a key role in the process.
BRK: For a recent TV commercial, an ad agency came up with the concept of a spokesman
standing next to a life-size virtual model of a perfectly-rendered Chrysler. As he talks about the
car, the skin dissolves to reveal the parts, etc. As I understand it, the agency used the actual engineering model, and rendered every little bit and piece of the thing. Fortunately, it only had to
be done to TV resolution, but it must have required a huge amount of computer power to render and animate all those zillions of components. The software and computer power necessary to do this sort of work at your sort of "garage" corporate level has only been available for a few years.  Is XR2 the first of your digitally-designed projects?
The beauty of an engineering model is that it ends up as a "real" representation of the actual prod- uct, not just an approximation of the outside surfaces. So it can be used for a variety of engineering purposes. For the home craftsman, those "engineering purposes" would include things like
machining parts and making decals from electronic files, zooming inside to see how it's built, and taking dimensions in three-dimensional space. With a mesh model of the outside surfaces (typical
of models made for appearance purposes), you couldn't do any of these things.

But if you try to import one of these engineering models into an animation program like 3D Studio MAX, you end up with a file that is so large it crashes the program.  So for animation purposes,
you have to go in and remove a lot of the detail in order to get the file down to a manageable size.
Consider that we now write electronic data to a plastic disc, then put the disc on a gas-guzzling truck and physically ship it to the end user, who then has to put the data back into an electronic environment in order to use it.  In the abstract, that ranks among the worst of all the dumb ideas
I've ever heard of. Why not just send the data over the Internet, and eliminate the plastic and the gas-guzzling hardware needed to transport it around the world.  Well, when high-speed Internet connections become more widespread, that's exactly what we'll do.  It's pretty exciting stuff, and
I feel lucky to be playing a role in pioneering a new way of doing things in  the do-it-yourself field.  It's not just 3D models, it's not just the Internet, and it's not just putting the same old product into
a new format.  There is a whole new universe of possibilities waiting to emerge.

So what was the question?
RQR: The first project I designed totally in 3D was a sink-mounted water faucet for a client who manufacturers a line of under-sink water purifiers. And the Project 32 Slalom was done totally in
3D, as well as a few others that are still under wraps.  So when I started on the XR2 project, I
was already using 3D in my consulting business.
BRK: I've worked with digital modelling and animation for television, so I've had a chance to check out plenty of digital models, including the one for the Titanic film. I've never seen so many details that were made for this model. I realize that as an industrial designer responsible for all those details, this level of precision detailing in a model created for such a purpose as this, is ordinary business. I took the model to pieces by deleting the objects which make it up, one at a time. What a task! I didn't make any attempt at counting all the bits and pieces, but there were an astonishing number of parts, most of them so tiny as to be almost invisible on the monitor screen. Have you
and Elusha recovered to the extent that you can look at the model and not feel immensely tired?
RQR: The original model did have a chain.  But the chain took more memory than the entire rest
of the model.  Imagine all those links with their side-plates and rollers.  The file was HUGE.  So
we tossed out the chain in order to make the model manageable.  At the last minute, I even tossed out the head bearings.  Elusha(Abdurakhmanov)  had modeled them with every single ball in place.

Also, Elusha did the sprockets, and he cheated a bit in a couple of places. He scaled some of them up, rather than making them in the new diameters as they should have been.  So I wouldn't totally rely on the accuracy of the teeth profiles.  Some will be accurate, and some will not.  We were
precisely accurate on any part that the builder would build himself.  But with the off-the-shelf items, our goal was to duplicate them fairly accurately, but not necessarily precisely.  So things like brake levers and calipers will just be semi-accurate representations of the real parts.  We took primary dimensions with a set of calipers, then sort of eyeballed the rest of it and went with the curves and sweeps that were not too challenging for Rhino.
If you're capable of disciplining yourself to the extent that you can follow the steps exactly to Mr. Riley's instruction, you will have yourself an incredible bike in an amazingly short amount of time. And you will find that there is no steep learning curve to any of the composite processes.  This is unlike building your own bike from metal, which involves becoming a competent welder and metal worker as a pre-requisite to starting the job. Composite construction is very simple in comparison, in that you only need to be meticulous in following directions. There are metal parts to be fabricated and modified, which would require that you be a competent machinist with access to a
The XR2 is an extremely sophisticated machine. It is as efficient a vehicle design as I have ever seen, aside from Bruce Bursford's Ultimate Bike. This means that it can be totally unforgiving if built wrong. I'm not saying that it would kill you; it just might not function if you build it too funkily. For example, relocating the forward bottom bracket an inch or so forward would mean that you might not be able to steer or pedal the thing. Mr. Riley covers all that sort of considerations in his very comprehensive technical notes. People who need more or less leg room than the range of the adjustable seat position are told exactly where to stretch or shorten the frame. The unmodified frame can accommodate riders from 5'3" to 5'11", so most people shouldn't need to change anything about it.