Seats

http://albums.photopoint.com/j/AlbumIndex?u=1025520&a=8431984
See USA patent Des 301218
Aluminium Recumbent Seat
See 'The Seat' part of 'A homebuilt Recumbent Diary' by Gary King in HUFF 5

Building the Seat by Rick Horwitz

Steve's Recumbent Project - Seat Detail

Barnett Williams The Contoured Recumbent Seat

From: Fred Larimer <flarimer@gurulink.com>
Grommets can be frustrating to use unless you get the right grommets for the thickness of your material. You might find it easier to use an idea from Rans. Sew an open ended hem along each side of the seat material.
Insert a 12 ga. rod in the hem. Stainless steel would be best. Melt holes with a hot nail in the hem every 1.5" BEHIND the rod. Lace the seat using the holes. I use parachute cord with good success. Don't use nylon cord from the home improvement stores - it stretches too much.

From: Jfreewheel@aol.com
Date: Tue, 13 Jul 1999 15:27:30 EDT
I know one guy who used a regular sewing machine to sew his web material. On the edges, it was folded and regular cloth was sewn together with the fold tucked in for greater strength. He then punched the grommet holes on the fold. You can buy this tool from most tool shops. It's like a puncher. You use this tool to press in the grommet holes.
As for meshing, I've seen soil control meshing. It's a plastic type mesh used to prevent soil from eroding. I think Home Depot carries it. It's also used on side of scaffoldings to prevent debris from flying off. The above guuy used this material and has been holding up.
J Gaerlan - Gaerlan Custom Cycles, http://www.gaerlan.com
Framebuilding,Recumbent and Bike Parts eStore
(415)362-3866: (415)677-8943 fax
JFreewheel@aol.com

From: Scott Talkington freewheeling@bigfoot.com
Seat material in different colors is available from HPVSupply: http://www.hpvsupply.com/catalog.html#seats
In addition, I noticed that some fiberglass screen material available at home building supply stores would make a decent seat. There are different qualities of this stuff, and you'd definitely not want to use the cheapest grade (which appears to be all Home Depot carries). I would think that this material might outperform regular nylon mesh, and it appears to be supple enough for a seat.

From: Fred Lenk flhpv@commpower.com
With regard to making grommets: I've found it hard sometimes to "punch" a hole thru some thicker materials with the tool provided with a typical grommet product.
I put the "punching" tool into a powered drill, as tho it were a bit, then "drill" thru the material. For double layers, after getting thru the first layer, I dig out the first layer from the punch tool, then "drill" thru the second layer.

From: Eric Warp ericwarp@jps.net
Subject: [hpv] Re: good source for mesh fabric
I found (what I believe to be) the best source for mesh seat fabric.
They're the same folks who make mesh for backpack frames, and man is this stuff tough. It's called Leno-Lock, it's $11.72 a yard, and here's the company:
Outdoor Wilderness Fabrics, Inc.
16415 Midland Blvd.
Nampa, ID 83637
(208)463-4622
They carry a full line of any kind of outdoor fabric, fasteners and straps you could imagine. They were courteous and shipped promptly via UPS. I highly recommend them.

Recumbent Seat by Jack Lee

Posted by Art Mulder on August 11, 1999 at 14:14:23:
Qn: Where can I get some of the nylon mesh that is commonly used on the seats for recumbents?
Ans: When I built my recumbent, my friend found me the seat material - he got it by dumpster diving behind a Tent+Awning store. The material is the type used in awnings over the front of stores. It is frequently changed and tossed when stores move or renovate.
It's not a very wide mesh, but it's still nice. I then picked up some inexpensive canvas and folded it around the edges (about a 3" wide band) and stitched it to the awning material. Finally I used a grommet kit to punch holes in the canvas
edge for stringing the ropes to attach the seat to the frame.

From: Mark Stonich
Subject: Brazing EMT / EMT for seat frame
Brazing EMT
Mechanical removal of the galvanizing is not enough, you won't get it all unless you are willing to remove a fair amount of the base metal. I use "The Framebuilders Secret Weapon" Sno-Bowl toilet bowl cleaner. Besides removing oxides and degreasing, it also is great for de-galvanizing anything you want to weld (gives off some nasty fumes though). Unlike other cleaners with Hydrochloric Acid, Sno-Bowl doesn't leave a residue.
Trouble is, the inside of EMT seems to be galvanized also, where it's a bit tougher to remove. Brazing fumes are bad enough without galvanizing so I always use a 3M welding fume mask (abt $7 US) AND ventilate. Sickest I ever got from welding was outside, so don't count on ventilation alone.
EMT for seat frame
I like to prototype a seat using 5/8" x 0.049" mild steel, which is similar structurally to 1/2" EMT, because I can bend, straighten and rebend till I get the shape just right. Then I can make the final seat from 5/8" x 0.035". 5/8" x 0.049" mild steel (or 1/2" EMT) is pretty marginal stuff to be building a seat frame from, unless you do a few things to limit the stresses fed into the seat frame.
Don't wrap the fabric around the frame and lace it in the back. Theoretically bending loads would double, compared to lacing the fabric directly to the frame. Increase is somewhat less because of the friction where the fabric wraps around.
Lace your seat fabric loosely to the frame. Tension on the fabric and bending loads on the frame rise dramatically, if you try to keep things tight. I don't have my formulas handy, but I'm pretty sure that if you try to limit maximum sag under load to 1", stress will be about 4 times as great as if you limit it to 2". When using the mild steel, if I try something like increasing the lumbar support by selectively tightening the laces, the frame just bows in.
A side benefit to loose seat mesh is that it feels much more solid, as you won't be stretching the fabric and flexing the frame. Have you ridden a late model RANS, with their drum-tight seatbacks? I tested a Gliss and thought that there was a lot of rear suspension pogoing whenever I pressed hard on the pedals. Then I tried a Tailwind (no suspension) and found it felt almost the same. Turns out I was trampolineing the seat, more than activating the suspension.
From: John Funk
Subject: carbon fiber seat
How to copy a Rans seat.
1) find a friend with a Rans seat and borrow it
2) take off the seat cover and foam padding
3) cover with 2-3 layers of plastic kitchen wrap. cover the back as well so that you still have a friend when you're done
4)slather lots of plaster of paris over the plastic
5) use more plaster of paris and add a piece of wood with some screws sticking out of it so the plaster has something to grab
6) take out of the seat
7) drywall compund on the mold to make it smooth
8) either paint and wax the mold or use lots of wax
9) lay up fiberglass I use 3 layers of mat and 1/2 quart of resin for one seat base
10) conduit! bend it so that it looks like the one you borrowed.
11) weld a little (be careful of the fumes. very nasty)
12) pop rivet the seat base to the frame
13) put on the bike
14) grin (one of those stupid big cheesy grins that shows you have the sweetest seat around and it cost peanuts.)

I figure my seat cost 15-20% what a Rans would cost. I use canvas for the seat cover and a plastic closed cell foam for padding that shows up in packing at my workplace. My friend said it felt pretty good and it weighs 1 lb more than his.

Robert Haston
Satellite Beach, FL US
Re: sand-casting mold for custom seat
I just tried using plaster of paris to make a cast of the impression I left in the sand. I had a beach handy, but there is no reason a box and some sand (the finer the better) wouldn't work fine. This was to serve as a mold for a fiberglass seat. The sand made an accurate impression, further, it was stiff enough to get a feel for the seat. But I failed in some key areas:
The sand got in the plaster too much. As I spread the plaster around, it sifted the sand, making the impression too rough.
I also couldn't build the more vertical portion near my neck.
To fix this, the next time, I recommend:
Make layers of plaster and cheesecloth (or burlap, old t-shirt material maybe, etc.) then lay these in the impression. Probably working in thin strips would be easier.
Gently lay these on the mold with a minimum of handwork.
Or as an alternative, you might lay a layer of fiberglass and resin between two layers of thin plastic. I will try both tomorrrow.
From: Leon Martin
Date: Wed, 12 Jul 2000
I wanted to share with you something I came up with for the adjustable seat on the recumbent trike. I was at a local auto salvage yard and I came across an older Ford Mustang with Bucket seats. I purchased the seat and removed the seat adjustment slides. I then welded two cross members onto the book and then welded the adjustment slide onto the cross members. My bike is not quite complete yet, but I really think this will work great.
From: Mark Maier
Date: Tue, 18 Jul 2000
Subject: GTR vs. GTS
List-Id: Recumbent Human-Powered Trikes <trikes.ihpva.org>

On 17 Jul 2000, at 18:11, michael deegan wrote:
I'm seriously considering ordering a Greenspeed, probably a GTR, but I would first like to get some opinions on seat angle. The GTR seat angle is 40 deg. versus 30 deg. for the GTS. I have no trike experience, but the seat angle on my Lightning Stealth recumbent is no where near as laid back. It's quite comfortable but I suppose the relationship of the seat to the bottom bracket is different than on a trike. I would appreciate any words of wisdom from you long term trike owners out there.

Before I got my GTS, I asked Ian a similar question (20 deg GLR or 30 deg GTS). His advice was to get myself a plank of wood, long enough for my back, set it up on the floor in front of the TV set at the angle of question. I would find out very quickly which angle is acceptable and which is not.
After less than 5 min I found 20 deg totally unacceptable, 25 deg was OK for not more than 30 min and 30 deg all right also for longer times. So I ordered a GTS.
At the time I decided about wanting 30 deg, I was owning a Flevobike Racer with an approx. 35 deg seat angle. This bike has now been replaced by a Challenge Jester which I have since 6 weeks. The Jester claims to have a seat angle of 23 deg and I actually don't have any problems with that (except slight ones, on that 230 km ride I did only 3 days after delivery). I guess you can get used to a lot...
From: Clint Everett
Date: Mon, 18 Sep 2000

Re: Grommets in Nylon webbing for building seats.
Don't cut the webbing, melt it.
Push a hot soldering iron tip through the webbing. It forms a raised ring of solid nylon with all of the strand ends firmly held in place. Then, while the material is still hot and pliable, set the grommet.
The melted ring of nylon will conform to the inner contour of the grommet shoulders and lock every strand of thread in place.
I laced a seat with heavy nylon webbing using this technique and have not had a single pull-out.
14 Jun 2001
alt.rec.bicycles.recumbent
"lewis60" <limeylew@home.com> wrote:

For those of you that might be interested in making your own seat, I have put together an album entitled ' Recumbent Seat ' (so appropriate, huh?)
http://community.webshots.com/user/tirush
The material I used is 1/2" EMT, otherwise known as electrical conduit, which is available at places like Home Depot for almost nothing. Your time is the main thing you will have invested here but you will have a seat that is lightweight and will never be a ' sweat box ' on a hot day. I purchased the mesh, seat cover, material from this friendly place:
http://www.poweroncycling.com/homebuilders_corner.htm ( item #FAB-001BL ) It comes in various colors and one yard will cover two of this style of seat.
Lewis.
```
 From: Peter Heal

Date: Mon, 25 Jun 2001
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There was a bloke making outdoor furniture here in Canberra that has since moved to warmer climes in Northern NSW. The material is a nylon mesh - I don't know it's name. It can be hi frequency welded so seams and reinforcement are pretty easy. I have the guys number and he understands what a recumbent is. Last seat meshes I got from him worked out at $22 each plus post $6 and took a couple of days. It comes in a couple of plain colours like Royal Blue and Dark blue all the rest that my bloke has are pastels or stripes - not the best look on a macho trike. Ian Sims also sells the mesh in any colour you want as long as it's yellow. I'll dig out his number tonight - actually it might be worth me talking to him about paying for an advert in Huff and I can write an article on seats.

Date: 26 June 2001
The chap I spoke of is: Neil Millynn PO Box 214 Coraki NSW 02 66832599 Neil will weld seams top bottom & sides and the width will be very accurate. On my seats i punch holes about 10mm in from edge, insert a brake cable down the welded seam and attach with zip ties to the frame. This provides a firm seat and there are no pressure points from eyelets and bungy cord. People I have asked with greenspeeds reckon they don't get problems with the cords etc.

Got a Greenspeed Parts "Dogalogue" last night. Ian sells the seat cover already sewn and eyeleted for $80 @750 - 1150mm long The Nylex Breezeway fabric comes in Red, yellow, dark blue, bright blue, dark green for $20 per metre @1400mm wide.
Mon, 16 Apr 2001
From: Fred Larimer flarimer@gurulink.com
Subject: RE: [hpv] rans seat mesh modification details
At 11:18 AM 4/16/01 -0400, Scott wrote: I wonder if you could write up this conversion in a bit more detail, for those of us who are "sewing challenged." What did your wife use for a "binding of 1 1/2 inch strap"? Is this a single piece of 1 1/2 inch webbing, or the nylon material used for the original seat? What sort of stitch and thread did she use? Do you basically just duplicate what RANS did, only on the "new" edges inside the uprights?

Glad to, Scott. I had written it up in some detail before so I didn't want to take too much bandwidth for the details again. What follows is even more detail.

I cut the mesh an inch narrower than the inside distance of the seat back tubes. A bit of space is needed to pull the mesh taut when lacing. The distance between the seat back tubes is narrower at the top than the bottom so cut both sides accordingly for a neat appearance.

The binding was black nylon strap available from an outfitter's store. Its used to make lashing and compression straps. Its probably a bit overkill but it is easily available, sews easily and looks good. It ran the entire length of each side of the seat mesh fabric. It was folded in half lengthwise to make the hem. My wife used a heavy duty polyester blend thread for minimum shrinkage and a zig-zag stitch. She ran two rows of stitching down each hem. The hem ends were trimmed to length and the cut edges heat sealed with a butane lighter to prevent fraying.

Insert the lacing rods in the new hems. I melted holes about every 1 1/4" along the hems for the lacing. The holes are about the size of an 8d nail. Parachute cord was used for the lacing. See note at the end about zip ties. The parachute cord ends will feed through the holes easier if you form a pointed end on them. Heat the ends with a butane lighter, when the melted nylon cools enough, roll the end between your thumb and index finger to form a tapered point. You might want a glove for this step.

Lace both sides up loosely leaving about 2x width of the seatback of extra cord at the top. After both sides are laced up, heat seal and tie off the bottom. Use a needle nose pliers to tension the cord and pull slack up through each hole in turn. Thumb pressure or a spring clamp pressing the cord against the seat tube will hold the tension. I did the first three wraps on both sides to establish the lateral spacing. Work your way up to the top. When both sides are evenly laced, the top can be tensioned similar to the way tent guy lines are tensioned with knots. Do this by tying a slip knot loop in the cord about an inch from the seat tube. Run the rest of the cord around the opposite seat tube, bring it back through the slip knot loop. Now you can pull on the tail of the cord to tension it. Tie it off at the loop with another slip knot or overhand knot.

Essentially we did duplicate what Rans did with heavier material in the hems. I thought the stresses on the "side" hems of the modified cover would be greater than the stresses on the hems of the stock cover so the heavier hem material would be a good idea.

Note: I tried zip ties but the 50# type commonly available at home improvement stores weren't strong enough. You haven't lived until you are 15 miles out on a fifty mile loop and find the zip ties giving way like a zipper. I had spares but they gave way too. 15 miles is a very long way to ride with only a rolled up jacket for back padding!

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Thursday, 29 January 2009