Tom Porters's lightweight recumbent bikes

Tom Porter's Ultra Lightweight Recumbent Bikes
Tom Porter of Wisconsin has built and raced a series of very lightweight (around 20 lbs), steel framed recumbents over the past several years. Though they are lightweight, they have held up quite well to Tom, who is on the high side of 200 pounds.

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Plans 2004 - Several recumbent plans and Tom's design philosophy
Tools - The tools you will need to build the bikes
Parts and Materials - What you will need to build the bikes and where to get it.
Welding and Brazing - Notes on welding and brazing.
As Built 2004 - Dual 700C high-racer version 1 & version 2
Plans 2005 - Revised Dual 700C plans, plus options.
Frame Build 2006 part 1 and Part 2 - Building the version 3 Dual 700C high-racer
Dual 700C 2010 - Ovalizing the tubes
LWB 2010 - Tom builds the long wheelbase bike
Making a stem jig 2010 - makes sure the handlebars go on straight.
Making a narrowed front fork 2010 - for lowracer chain clearance

RWD Ultra lightweight recumbent

This is the SL (superleggera) rigid 20lb bike I built in 1999.This bike was built to build the lightest cr-mo tubes bike I could to see if it would hold up. To hell with the consequences! The specifications are 1 1/2 x .035 bi-axial formed main tube, 1" x .035 rear stays formed at rear for my handmade dropouts. This bike has all the lightest components I have on it but the seat is conduit and pffiertex fabric which adds a lot of weight, I intend to obtain a CF M5 seat with will save a few lbs and get to the 18 lb range.

Frankly I'm surprised this bike has lasted given my weight but to date shows no signs of stress fractures so I'm quite happy about that.

FWD rear suspended lightweight recumbent

Number two is the direct drive FWD that was modified from the lay-down bike I built in 2000. This bike was raced several time in 2000/2001. I decided to change this to what I'll call my urban lowracer as the seat height is 12" and I can see traffic safely. 

The lay-down concept may be good for flat track racing but I feel does not work well for hill climbing, like not at all. Specifications on this bike are 1.75" x .035 main tubes, 1" x .035 rear stays ovalized with pine blocks in a vise and heat formed to fit my own made dropouts. 
This bike was built with a rear suspension only at first, to get that idea straightened out before taking on the suspension fork design problems. The gear range with 72/53 rings is 35-110 inches approx. The 72T ring is from The front spacing is 130mm and rear spacing is 100mm.
This picture shows the detail of the elastomer based rear suspension. Brass bushings are used in the pivot to provide smooth movement.
FWD fully suspended lightweight recumbent

The TRS (Tom Ries Streamliner) was built as the lightest possible cro-mo framed, fully suspended FWD bike I could possibly build. The frame specs are 1 1/2 x .035 main tube with bi-axial forming with the wood block method to obtain ovalization in the proper areas. 

I decided to use 1 1/2 tube after I couldn't locate 1 3/4 x .028 which what I really wanted to use. The tubes were gas welded with 4130 1/16 rod at the miters and than covered with a formed gusset brazed to reinforce the joins. The rear stays are 7/8" x .035 again ovalized with wooden blocks and formed to my own hand made dropouts. The stays pivot on bronze bushings in tube through frame. the upper suspension mounts in a 1" x .035 tube mitered and inserted completely through the frame. 
The frame with suspension unit mounted weighs just over 5 lbs. The front fork is a cro-mo 700c fork, most bike shops have these laying around for free or next to nothing. The fork blades were first straightened out and then rough cut to a 406 wheel length. Then were formed into a S bend to 130mm spacing and my own dropouts inserted.
The drive systems is 155mm BMX cranks with a single 110mm chainring, initially a 48 tooth ring will be used, the chainrings bolts are a BMX item for a single ring. The intermediate drive is a HG freehub body with threads on the outer edge, this is a fairly old item but is necessary because the freehub is bored out on a lathe for 10mm x 30mm sealed bearings, Ralph Koser did the machining using a carbide tipped tool bit because the freehub is hardened. 
The more recent freehub bodies have an internal thread to mount the locking ring whereas the older style used a threaded gear to lock everything into place. Using various spacers a 14T and 24T steel cogs were used to drive to the 9 speed cassette. I'm not sure but these are probably some old Dura-Ace with sufficiently deep teeth to engage the chain, seems most cogs are now use shorter teeth and the chain will unship with too much deflection. The cogs should be closer in profile to a chainring's cogs. 
The front derailleur is a braze-on mounted upside down with the cage shortened for clearance. The derailleur on the fork is a newer Ultegra (11T pulley) shot cage as it will handle the chain wrap. The cassette is an Ultegra 12-27. Gear inch range is 31 - 125 inches. The adjusting boom is all steel that will eventually be replaced with an all aluminum boom and bb spindle. 
Here's the bike frame next to Tom Ries' Baron. It looks slightly longer and a little lower.
Tom Ries says: "I rode it, just for a feel. (note: no brakes yet!). Very nice rear suspension. He's going to get a softer front elastomer. The FWD seems very smooth as well."

The suspension units still need to be tuned because the rear with a 60A durometer elastomer is a bit to soft for TR's weight (170 lbs) and oscillates as he pedals and the front also with 60A durometer is to stiff and barely moves so I have get these adjusted in the next couple of weeks. The steering is also a cobble job just to get the thing rideable. 

June 2010
Here's the latest version of Tom's SWB dual 700C high-racer, with ovalized 2" tubing.
Here's Tom's 2010 build, the LWB.

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