S40 New frameset build plus Thor seat.

[Decher Kritzmire]

After about 600 miles and too much time personalizing (mostly the seat) I think I have this dialed in and worthy of sharing in the event that there's any take aways for someone else.
Brief background: 62 years old, 20 on recumbents mostly high racers of various brands. The development of cervical stenosis has made the reclining seat and forward neck curvature uncomfortable. While I could raise the seat on my previous Metabike the high bottom bracket created a closed hip angle unfriendly to my arthritic hips. Isn't aging fun. My goal was to have a high racer style bike with upright seat and lower bottom bracket to open and elongate the hip angle. The S40 looked promising due to the downward rotating boom adjustment. I have fairly long legs and estimated that the resulting BB height would be good.
Build points: This is a 2x9 set-up:
DaVinci crank arms, 160mm, 110/74 spider set up as double with TA Zephyr 44t middle ring and 27t Rotor Q inner ring, 11-34 cassette w/ XTR der
Microshift thumb shifters, front is friction
Soma Gator bar
Shimano Tiagra flat bar road brake levers with TRP Spyre brakes
White Industries CLD hubs on Velocity Dyad rims
Origin8 steer tube extender cut to desired length
Thor seat and Ventisit pad (thanks to another forum member for the sale) - I spent a lot of time (as many of you did) trying to get the seating comfortable, not too reclined for the neck, not too upright for the lower back and recumbutt, etc, etc. The curvature of the Thor seat was much better than the stock seat but the depth of the contour felt excessive. I wasted a bunch of scrap foam sleeping bag and yoga pads adding and subtracting layers to change the contour until I reached one I could comfortably live with. Actually, its really pretty darn good. I'll post the seat mounting system I used in a second reply.

 

[Decher Kritzmire]

Seat mount: I did shave of the lower wing ends and mounted the bottom directly to the frame with a 3-stack of big rubber washers between. At the top I used a remnant of 1/4" HDPE sheet that I had, cut into rectangles that I could stack and adjust 1/4" at a time. I think I ended up using 4 layers, the bottom one slightly visible above the bracket in the photo. If you are not familiar with HDPE it is a very resilient, tough, marginally flexible plastic like material that tools like wood. Mine was originally a 4x8 sheet from Menards from which I had leftovers from. I did end up adding and then taking away layers a couple times. The rear bracket is an 1/8"x 1"which piece of aluminum bar (also from Menards). I hand bent the curvature around the top of a peanut butter jar ( high tech, right? ) but it fit well. The Velcro strip does help to hold it in place during changes and also protects the frame. I did not bother with any mid support as most bikes don't have that and this attachment is firmer than any seat strut mounting I've ever had on previous bikes. I did pack some left over foam between the seat and frame, not for structural support, but it does seem to help deaden the sound/vibration transfer through the frame to seat.

 

[ak-tux]

After about 600 miles and too much time personalizing (mostly the seat) I think I have this dialed in and worthy of sharing in the event that there's any take aways for someone else.
Brief background: 62 years old, 20 on recumbents mostly high racers of various brands. The development of cervical stenosis has made the reclining seat and forward neck curvature uncomfortable. While I could raise the seat on my previous Metabike the high bottom bracket created a closed hip angle unfriendly to my arthritic hips. Isn't aging fun. My goal was to have a high racer style bike with upright seat and lower bottom bracket to open and elongate the hip angle. The S40 looked promising due to the downward rotating boom adjustment. I have fairly long legs and estimated that the resulting BB height would be good.
Build points: This is a 2x9 set-up:
DaVinci crank arms, 160mm, 110/74 spider set up as double with TA Zephyr 44t middle ring and 27t Rotor Q inner ring, 11-34 cassette w/ XTR der
Microshift thumb shifters, front is friction
Soma Gator bar
Shimano Tiagra flat bar road brake levers with TRP Spyre brakes
White Industries CLD hubs on Velocity Dyad rims
Origin8 steer tube extender cut to desired length
Thor seat and Ventisit pad (thanks to another forum member for the sale) - I spent a lot of time (as many of you did) trying to get the seating comfortable, not too reclined for the neck, not too upright for the lower back and recumbutt, etc, etc. The curvature of the Thor seat was much better than the stock seat but the depth of the contour felt excessive. I wasted a bunch of scrap foam sleeping bag and yoga pads adding and subtracting layers to change the contour until I reached one I could comfortably live with. Actually, its really pretty darn good. I'll post the seat mounting system I used in a second reply.

Nice !

The seat almost looks like two in one!