I'm thinking of getting the plans for this, and building it as a trike.

Frame is foam core with carbon fiber or fiberglass skin, polyester resin. According to the designer, the frame can be built for under $150.00, including the 6001 series aluminum bits and shock for the rear suspension. I have a Miami Sun trike that can donate the trike rear, or maybe I'll just get a low rider trike conversion kit.

Your thoughts?

Of all the plans that guy sold, I think two or three 'bents were actually built. But I've never seen one on the road; so I am guessing that something about it is incredibly hard to do to make all those plan-owners decide against building it.

U-Joint steering is very finicky - you have to get a high quality u-joint with no slop, and when it starts getting worn, you have to replace it pronto. It also adds complexity, which may be one reason why you don't see more (or any) of those on the road.

Of all the plans that guy sold, I think two or three 'bents were actually built. But I've never seen one on the road; so I am guessing that something about it is incredibly hard to do to make all those plan-owners decide against building it.

U-Joint steering is very finicky - you have to get a high quality u-joint with no slop, and when it starts getting worn, you have to replace it pronto. It also adds complexity, which may be one reason why you don't see more (or any) of those on the road.

Blazing,
It seems to me that a very simple bevel gear would work much better than a u-joint. Been used on trucks, tractors and cars for a gazillion years. Would also provide a way to incorporate some ratio adjustment into the steering. Wouldn't have to be precision or heavy gearing. You could probably recycle some parts off an old riding mower in a pinch.

I too have wondered why I have never seen one of these. The design looks kinda cool.

Blazing,
It seems to me that a very simple bevel gear would work much better than a u-joint. Been used on trucks, tractors and cars for a gazillion years. Would also provide a way to incorporate some ratio adjustment into the steering. Wouldn't have to be precision or heavy gearing.


You're right, a bevel gear would work. It may have the same issues wrt slop, and it might be more expensive than a u-joint, but it seems it would do the same job. I only offered that as one explanation for the discrepancy between plans sold and units built. I personally don't think it looks all that cool. Take away the one curved piece and replace it with a short straight length of tubing, and it'd look pretty plain. Maybe the difficulty in making the curved piece is what the problem is?

The groundhugger is a very lightweight machine. It's the design that originally got me interested in recumbents. Lightweight materials is its advantage. Why would you want to add extra weight by turning it into a trike?

No, you can't build it for $150 -- not unless somebody gives you the components, including carbon fiber and epoxy. Carbon fiber and epoxy, and bidirectional fiberglass with epoxy are materials used on aircraft. They give you a very strong, yet lightweight structure. However, they are costly materials.

Thanks for the input. The frame is a Styrofoam core (from Home Depot or Lowe's) which remains after the carbon fiber or fiberglass skin is applied. A knife or jigsaw is used to cut the frame from the 4 x 8 sheet of Styrofoam. Sand paper, and rasps are used to contour the foam before the skin is applied. A polyester resin is used, not epoxy, which requires an autoclave. Polyester resin does not need an autoclave. Bidirectional fiberglass is also used in the automobile and boat industries. Check out the Chevy Corvette, fiberglass body from day one, and any of the myriad of fiberglass hulled boats.

I was thinking of building it as a trike, because I have never ridden a recumbent of any kind, and although I have over 45 years riding upright bikes, I do not know if I could balance a 2 wheel recumbent, or get one rolling from a stop sign without falling on my a**. I am too old to fall on my a** these days. Also, a trike would make it easier to mount rod holders for fishing, carry camping gear, and so on. For me, a trike just makes more sense, I think. The only other viable option I can think of would be an EZ-3 of some type.

I'm familiar with carbon-over-foam-core construction. I'd recommend that rather than fiberglass. Both use essentially the same technique, but fiberglass will result in a heavier, flexier frame. As low as the Groundhugger is, falling won't be a big problem except for your ego; but there's probably an easy way to connect the main frame to a trike rear end. Just don't make your FIRST project too complicated so that it prevents you from completing it.

Can you make this thing with glass? The only composite plans I saw on their website were for carbon fibre, with an estimated construction cost (excluding tools - and CF is hard on scissors) of just under $300.

I'm genuinely curious as to why you'd like to build this particular bike. While it may be light, composite building is pretty toxic and it sounds like you're already thinking of hacking the design, which may have implications for handling etc. Have you checked out their forum to see if anyone else has done this?

I guess I just get kind of uneasy when I see the only detailed pics on the site appear to be "prototypes" and could find little in the way of building experiences online.

I just completed a recumbent bike this year. I had to learn to ride it, the way I did when I first mounted a bicycle. I just had to go to an empty parking lot and gently coast downhill. Then I had to learn to ride it in that empty parking lot. It took twenty to twenty five hours in that parking lot, before I was comfortable enough to ride around other people. I had to do that to retrain my muscles. My recumbent is much more comfortable.

CF is hard on scissors

Negative. Cutting carbon is like cutting cotton. I can even cut it with incredibly cheap scissors from the dollar store, with no apparent effect on them. Glass, now THAT'S hard on scissors. It may feel soft to the touch, but it's... silicon! stone!

Negative. Cutting carbon is like cutting cotton. I can even cut it with incredibly cheap scissors from the dollar store, with no apparent effect on them. Glass, now THAT'S hard on scissors. It may feel soft to the touch, but it's... silicon! stone!

oops, good catch, I was thinking of kevlar..

there is a guy here in toronto that made his own carbon fiber trike , amazing looking

I think it would be a great project. I'd love to see you do it.

I suspect you're going for "light" in your version, but I did this 150 lb, electric hog, in steel. Used 2 U-joints out of small Honda car tack Mig'ed together for steering.

here is some pic links to the trike from vic's HPV site http://vic.gedris.org/pics/2007-11-11/MD-2007-11-11-008.html http://vic.gedris.org/pics/2007-11-11/MD-2007-11-11-025.html