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Step 6Step Six: Making the Seat
To get the right shape, I started by tracing an outline my wife's torso. Based on other designs I've seen, I then modified the outline to provide support where it is most needed. I transferred the pattern to a sheet of 3/8" plywood I had in my scraps and cut it out using a jig saw. Then I cut it into 2 pieces to create a seat and back. I then added hinges to allow the seat to recline.
In the base of the seat, I drilled slotted holes for 1/4"x2 1/2" carriage bolts which would be used to mount the seat to the frame. The slots allow the bolts to be adjusted left and right to accommodate for the seat tubes. On the back of the seat I also drilled a hole for a 1/4"x2" carriage bolt for the bracket which would be used mounting the new seat stays.
Next, I bought some dense foam rubber mats from the flooring section in Lowes. It ran about $17 for a package of four 24"x24"x3/8" pieces - enough to make about 2 seats. I cut the foam to roughly to the shape of the plywood pieces and glued them to the plywood with rubber cement. Then I added a second layer by the same process. Using a 5" sanding disk attached to my drill and 150 grit sandpaper, I shaped the foam rubber to create a slight lumbar support and cupped areas for the upper back and buttocks.
To cover the seat I used 2 pairs of 'fat lady', black, winter tights. I cut the legs off and worked them on starting from the top. After I had added all four layers, I simply pulled them around over the front and stapled it to the bottom of the seat. If I did it again (and I'll likely have to), I'd use cotton tights or something similar. Even though the material is pretty tough (and considering who they're designed for, they'd have to be) they have already started to develop runs.
The entire assembly was mounted to the frame using 5/8" adel (rubber lined) clamps around the top tubes, then a 1/2" nylon spacer, and a fancy wing-nut. The spacer simply provides room for the nut to turn. The pictures provide the best details.
The rear mounting bracket was actually fashioned from a swingset clamp. I drilled three holes - one to bolt it to the seat and the other two for mounting the seat stays. The seat stays are simply 24" pieces of 1/2" conduit that has been squashed to an oval shape on the end that mounts to the seat bracket, with a 1/4" hole drilled about 3/8"" from the end of the tubing.
To mount the stays to the bike, I originally attempted to use adel clamps using a setup similar to that which was used for the seat bottom (1st picture). However, I found that under load the clamps had a tendency to slip no matter how much I tightened them and though I had originally intended to use the old sissy bar from the CCM bike it proved unstable. I decided to instead drill a series of 1/4" holes spaced 1" apart. A 1/4"x2 1/2" carriage bolt is inserted though the rear dropout followed by a 1/2" nylon spacer, the seat stay, and finally a wing-nut to hold the entire assembly in place.
In the base of the seat, I drilled slotted holes for 1/4"x2 1/2" carriage bolts which would be used to mount the seat to the frame. The slots allow the bolts to be adjusted left and right to accommodate for the seat tubes. On the back of the seat I also drilled a hole for a 1/4"x2" carriage bolt for the bracket which would be used mounting the new seat stays.
Next, I bought some dense foam rubber mats from the flooring section in Lowes. It ran about $17 for a package of four 24"x24"x3/8" pieces - enough to make about 2 seats. I cut the foam to roughly to the shape of the plywood pieces and glued them to the plywood with rubber cement. Then I added a second layer by the same process. Using a 5" sanding disk attached to my drill and 150 grit sandpaper, I shaped the foam rubber to create a slight lumbar support and cupped areas for the upper back and buttocks.
To cover the seat I used 2 pairs of 'fat lady', black, winter tights. I cut the legs off and worked them on starting from the top. After I had added all four layers, I simply pulled them around over the front and stapled it to the bottom of the seat. If I did it again (and I'll likely have to), I'd use cotton tights or something similar. Even though the material is pretty tough (and considering who they're designed for, they'd have to be) they have already started to develop runs.
The entire assembly was mounted to the frame using 5/8" adel (rubber lined) clamps around the top tubes, then a 1/2" nylon spacer, and a fancy wing-nut. The spacer simply provides room for the nut to turn. The pictures provide the best details.
The rear mounting bracket was actually fashioned from a swingset clamp. I drilled three holes - one to bolt it to the seat and the other two for mounting the seat stays. The seat stays are simply 24" pieces of 1/2" conduit that has been squashed to an oval shape on the end that mounts to the seat bracket, with a 1/4" hole drilled about 3/8"" from the end of the tubing.
To mount the stays to the bike, I originally attempted to use adel clamps using a setup similar to that which was used for the seat bottom (1st picture). However, I found that under load the clamps had a tendency to slip no matter how much I tightened them and though I had originally intended to use the old sissy bar from the CCM bike it proved unstable. I decided to instead drill a series of 1/4" holes spaced 1" apart. A 1/4"x2 1/2" carriage bolt is inserted though the rear dropout followed by a 1/2" nylon spacer, the seat stay, and finally a wing-nut to hold the entire assembly in place.
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