Overview of
Building the GNAT>>

If you want a GNAT, you will have to build it yourself, from a kit.
This page gives an idea of what is involved, and describes what you need.


It is anticipated that demand for GNAT kits will exceed supply for some time. During this period, it is unlikely that you would be able to buy a kit unless you gave the impression of being able to assemble it. Ultimately though, it is for you to satisfy yourself that you are capable of doing this. I hope these pages will enable you to decide. If I have not made anything as clear as it should be, please feel free to email me - Nick - at the address on this page.

To assemble a GNAT kit, you do not need any big or expensive bits of equipment. If you maintain your bicycle yourself, and do a bit of DIY at home, you'll probably have most of the things needed. Neither are there any really difficult steps to building the kit. Success is mostly a matter two things:

firstly, preparation:

and secondly, methodically organizing simple manual techniques, such as:

Carbon fibre is nicer stuff to look at than to work with: it blunts ordinary cutting tools in seconds, and the fibres penetrate one's skin easily. Fortunately you do not need to do a lot of work on the carbon components, and you will find building the kit a good introduction to this wonderful material.

The aluminium angle brackets and glass-composite chassis don't present much difficulty to finish: these materials cut easily with an electric jigsaw.

The steel parts - wishbones &c - in the kit are finished, except possibly for painting. You may need a couple standard-size taps for cleaning out threads.

 

 

How the GNAT is put together

Most recumbent trikes (and bikes; as well as conventional bikes) are built around a metal chassis to which a seat is attached. The GNAT, however, has a composite chassis which is also the bottom part of the seat, and to which just about everything else is screwed. The GNAT's moulder, Mike Nelthorpe, refers to this moulding as the monocoque. I usually call it the chassis.

Some people see the chassis of the finished trike and look for a 'proper' metal frame underneath. However, glass fibre is stronger than steel, for its weight, and wishbones are an especially good means of making attachments to it, since they reduce loading and spread it over wide areas. This section gives more information on the chassis.

Building the kit involves cutting holes in the chassis - for the trackrods, chain, and cables to pass through. The glass composite is not difficult to cut; you can do it with ordinary tools. This page tells you how.

Eight L-section light alloy brackets attach the wheels, front boom and seat back to the chassis. These brackets can be supplied in the kit with holes already drilled - and countersunk, in the case of the bearing holes which give suspension and folding. You do need to shape them; this page gives instructions. An electric jigsaw does the job nicely, along with some other basic tools like files and drills, and it is not difficult to make a nice job of it.

When you have shaped the brackets you need to stick them to the glassfibre chassis. Car-body filler is recommended as an initial adhesive here.With the brackets fixed, you drill through holes in the brackets into the chassis, then attach them securely with screws. This way makes it easy to end up with the brackets securely fixed in exactly the right positions. Read this section for full instructions.

Both the rear fork, and the front boom brackets, use a belt-and-braces approach involving bonding and screwing to make metal-to-composite joins. The rear fork is the biggest job, apart from the chassis. Read this chapter to see what it involves.

The GNAT's seat is sewn from fabric, using a sewing machine. You might want to do this yourself, or get someone else to do it, or you could perhaps buy a readymade seat with the kit. This section gives guidance.

The rest of the work is basically fitting, and is the easiest and probably the most enjoyable part of building the kit.

Building the GNAT>>