adjustable seat

[Greenhorn]

I am trying to come up with the most simple, cost effective way to make an adjustable seat for my highroller. At first I was going to try and copy the Rans or Volae design, but both of those require moving parts at the top and end of the seat stays, as well as the bottom of the seat. This seems to be a complicated design and would result in frame flex, as the bike could flex at all of the joints. --That would seem to waste a lot of power. I do not want to slide the seat fore and aft; I just want to be able to adjust the recline position.

I am out of ideas and looking for opinons.

I have gone through about 3 or 4 different designs in my head, and so far the best I can come up with is as follows:

1. Make a "hard" rear triangle as called for in Brad's plans but change the angle on seat support to the lowest I may want to be reclined.

2. Make an aluminum or wood (probably aluminum) seat with appropriate bends.

3. Add two pieces to the back of the seat about the length of the seat tabs in Brad's design, but with the centers hollowed out (or with multiple holes) that will mate with the seat support bar and can be adjusted to slide back and forth. (I don't know if that was a good explanation...I saw this method utilized by Challenge on some of their bikes)

http://www.challenge-ligfietsen.nl/images/fotos/ventus/ventus-1.jpg

http://farm4.static.flickr.com/3172/2712397208_0220d1b632_o.jpg

4. Add a bracket to the underside of the seat |-| that will mate with a bolt to two slightly skinnier tabs | | welded to the main boom.

The idea is that you loosen the bolt at the bottom of the seat and the bolts on the tabs on the seat back, which allows the seat to pivot from a fixed position.

I hope that description made sense.....One of my earlier plans was to make the actual back seat support pivot, but on further consideration that seemed it would result in a loss of power transfer and contribute to flex when peddling hard.


Comments and critiques would be most welcome. Thanks!

[theDude]

I don't know if it will help, but here's how I made the seat for my Meridian. It's pretty simple and easy to adjust. There are holes drilled through the outer steel tube every 1/2" that a spring type cotter pin slips through to hold everything in place.

http://www.projects.archersdad.com/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=172 (http://www.projects.archersdad.com/wpg2?g2_itemId=171) http://www.projects.archersdad.com/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=169 (http://www.projects.archersdad.com/wpg2?g2_itemId=168)

[comreich]

I have a very similar setup on my lowracer. The front support bar of the seat is attached to two tabs that slip over a 4" piece of 3/4" square tube, with the tubing drilled out with 1/4" holes at 1/2" intervals. This allows some adjustment of the seat position relative to the bike for weight distribution. The upper seat support tube also has two tabs welded 1 1/4" apart with a piece of 1/2" tubing welding between the 1/4" holes in the tabs. Then I have two pieces of 1/8" aluminum to act as support struts and 4 1/4" holes drilled at the opposite end from the seat which allows me to slip a bolt through them and a similar 1/2" tube welded to the top of the rear frame member. With a 45 degree bend in the seat, the seat can recline to a little under 30 degrees from horizontal.

It's the not the best picture to explain it, but you should be able to get an idea of the construction from here. The Challenge seats are much prettier versions :)


One thing to note is that the front seat support is very narrow and appears to wobble a tiny bit. Until I get this on the road I won't know how stable it will be in the long run.

http://comreich.ods.org/~reich/lowracer/2009-02-22%20lowracer.jpg

[Greenhorn]

Yes--that is very similar to what I had in mind. Thanks for the pic!

[Odd Man Out]

I am trying to come up with the most simple, cost effective way to make an adjustable seat for my highroller. At first I was going to try and copy the Rans or Volae design, --That would seem to waste a lot of power. I do not want to slide the seat fore and aft; I just want to be able to adjust the recline position.

Thanks!

I mainly ride with RANS seats and while you can slide them fore and aft, you do not need to to adjust the recline angle by just adjusting the seat stays. The RANS seat feels rock solid and does not move when you apply pressure to the cranks. No power is "wasted". I would say a word of caution about the fanaticism of power; recumbents use a different style of pedaling than DF's -- DF's use gravity and the riders weight to stand on the pedals to "push" the speed up hills. Recumbents shift down and "spin" -- trying to power a recumbent along consistently is a sure recipe for blown knees and other problems. Buy a set of RANS seat stays and adapt them for your HR -- the easiest solution out there. Hope this helps.