The seat tube and head tube are made out of fiberglass, brown packing paper, and birch veneer all wrapped around a pipe used for a mandrel. For the seat tube I used part of an old shower curtain rod with the decorative plastic removed. It just happened to be the same diameter of my seat post. For the head tube I used 1 in. pvc pipe that had an outside diameter of 1.3 in.



I planned to attach a front derailleur to the seat tube so I had to pay attention to both the inner and outer diameter of the tube. The seat post was 1 in. in diameter and the derailleur needs a 31.8 mm (1 1/4 in.) seat tube so I had to make the tube 1/4 in. thick (1/8 in. on each side). I also integrated the old bike's seat post clamp into the tube so I wouldn't have to figure out how to put it on later.



There are some helpful websites for amateur rocketry that provide instructions on how to make fiberglass tubes, but my experience was difficult. It took 3 tries to make the seat tube. The first attempt made a tube with an internal layer of paper that was way too loose. The 2nd attempt was a very tight tube of fiber glass and paper, but it wouldn't slide off the pipe. Finally I made a tube of only fiberglass and with effort was able to pull the pipe out. The head tube is much smaller and slide off the pipe fairly easily.



Here's the steps I finally used:

1. Sand the pipe so it's smooth

2. Lubricate the outside of the pipe, with grease or wax, but leave the ends

clean so the wax paper can be taped on.

3. Wrap the pipe with wax paper, and tape the ends so it stays in place.

4. wrap the tube two times with fiberglass and epoxy. Using latex gloves I was

able to wrap the epoxy soaked fiberglass flat onto the pipe so that there no

bubbles or gaps. Don't make it too tight though or it will never slide off.

5. Let the the tube cure, but not completely.

6. Remove the pipe: Remove the tape then break the pipe free by locking the fiberglassed section into a vise and twist the pipe with pliers. Work the pipe out by pulling and twisting with the pliers on one end and push the pipe with a stick or smaller pipe on the other end. Take care to cause as little damage as possible but there will be some.

7. Remove the wax paper, and slide the fiberglass tube back on the pipe. Sand it and coat with more epoxy and wrap with several layers of paper to add some thickness and add some epoxy as you go. The paper doesn't need to be soaked with epoxy.

8. Let it cure. I used some cord to keep the paper tightly wrapped while it cured.

9. Sand the pipe again, and measure the circumference, to get an idea of how much veneer is needed. Cut the veneer so it overlaps the pipe by about a 1/4 - 1/2 of an inch and sand the inside edge of the veneer to a sharp blade (the outside edge gets sanded after the epoxy cures). The blade edge will go down first then the opposite edge will lap over it.

10. Add another layer of fiberglass and epoxy followed by the veneer layer. The veneer bends easier once it's been wetted out with epoxy.

11. Let cure. This time I used wire ties to the keep the veneer wrapped around the

tube.

12. Sand the veneer to get rid of the over lapped edge, and to remove any marks or indentations caused by the wire ties.

13. Finally apply the last layer of fiberglass.

14. Let cure

15. Sand it smooth.



The Head tube ended up being 1/8 inch thick with an inner diameter of 1 5/16 in. and outer diameter of 1 9/16 in.



I originally tried to use a 28.6 mm front deraileur, but it wouldn't fit, so I added another layer of fiberglass at the bottom of the seat tube and used a 31.8 mm derailleur. The seat tube finally had an inner diameter of 1 1/16 in. and an outer diameter of 1 5/16 in.

