How to Build a Lightweight Recumbent Bicycle Seat

In a recumbent bicycle seat, the rider can achieve a more comfortable, ergonomic posture.

For anyone who just built or bought a recumbent bicycle but did not yet obtain a seat, the prices on store-bought seats can come as a bit of a shock. Fortunately, with a bit of welding prowess, one can build a seat for considerably less than the cost of a new seat. Since recumbent bicycles already tend to be heavier than traditional, upright bikes, weight is an important consideration, and a lightweight seat made from electrical conduit tubing is an ideal solution.

Instructions

1. Cut the conduit to the appropriate lengths. The sides will start out at 36 inches long, and will be made from the 1/2 inch tubing. The seat stretchers will each be 24 inches long and made from the 3/4 inch tubing. Cut each piece of tubing in half, then clean the cut ends with a file.

2. Bend the conduit pieces to form the seat sides. Each side will have to be bent exactly the same way, and each bend should be made in plane. First, bend one of the 36-inch pieces 45 degrees at the end so the center of the bend is at about 4 1/2 inches. Next, bend the conduit 90 degrees in the opposite direction, with the bend centered 12 1/2 inches from the end. Then, make two 15-degree bends in the same direction as the first bend, centered at 19 1/2 and 22 1/2 inches from the end. Finally, bend 20 degrees opposite the initial bend, centered at 28 3/4 and 32 1/4 inches. Perform the same bends on the other one.

3. Bend the conduit pieces to form the seat stretchers. Bend one 3/4 inch conduit piece 60 degrees, centered 6 inches from one end. Do the same bend, in plane and in the same direction, 60 degrees and 6 inches from the other end. Perform the same two bends on the other piece to form a second seat stretcher.

4. Braze the seat together. Connect the ends of one of the seat stretchers to the seat sides, centered between the 90 degree and 45 degree bends, approximately 8 inches from the end, keeping the seat sides in plane with one another. Connect the other seat stretcher between the adjacent 15 and 20 degree bends, about 25 1/2 inches from the end. Make fish mouth cuts on the ends of the seat stretchers to fit them to the seat sides, then braze each connection.

5. Attach the fabric cover to the seat. The fabric comes 54 inches wide, so cut it in half to form two 36 inch by 27 inch pieces, one of which will be used for this seat. Center the fabric on the seat so the long dimension goes along the vertical axis of the seat. Fold the ends over the sides of the seat, cutting where the seat stretchers are so as to fold around them, then hold them in place with the straight needles. Sew, using the fishing line, keeping as close to the seat rail, and maintaining as much tension on the seat as possible.

6. Finish sewing the seat together. Cut along the seat rails to remove the excess fabric, then trim the extra fabric at the ends, leaving about 1 1/2 inches of fabric at either end. Fold each end over, and sew a seam at the top and bottom of the seat, again taking care to maintain the tension in the seat.

Tips & Warnings

• When bending the conduit for the seat rails, make the corresponding bend on each piece before moving on to the next bend. This way, you can make sure that the bends all line up when it is easier to fix, before all the bends are made.

References

• Recycled Recumbent

Resources

• Drawings for Recumbent Bike