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  1. #1
    Join Date
    Jan 2015
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    in transit
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    Default Recumbent trike.

    Thought Id share this, someone might find it interesting. I was moved to write this because I can no longer ride my recumbent and probably never will again, what a barrel of fun this thing was. It's pretty well worn out now after almost 10 years use, but it makes a good shed ornament. I now ride an MTB.

    Id always wanted a recumbent bicycle, but when I saw my first tadpole about 14-15 years ago, I just had to have one and set about making one. All in all I made four of them, trying out different designs, wheel sizes, gear changing mechanisms, steering configerations, and so on. This was my final, Everything either came from the tip or from my box of bits, except the front hubs, rear rim, S/S spokes, three chains, brake levers, cables and tyres.

    Main frame section was made from Square tubing and the rear from 20mm round tube. Bottom bracket was cut from a bicycle frame and welded to the non adjustable front extension. A short tube was also added for front deraillleur mounting and a modified rear derailleur mounted underneath the extension for chain tensioning, Behind the cross beam I mounted a threaded bottom bracket section about 20 mm long into which a bottom bracket bearing retainer is threaded and a modified rear cassette threaded over that for intermediate gearing. On the main frame above that is another short tube onto which is mounted a modified front derailleur. Seat brackets are welded to the mainframe and under that the handlebar mounting. Behind the seat bracket on the main frame are another couple of brackets for chain idlers. The rear wheel carrier is attached to the the main frame below and the seat support at the top. Axle mounts where cut from 3mm steel plate and welded in place, they include a threaded section for mounting the rear derailleur. I also welded short 6mm round cable retainers at various points around the frame.
    .
    King pins are bushed with bronze bushings. Welded to the kingpins is a centre bored 12mm stub axle, tapped to accept a 6mm bolt for wheel security. Also welded to the kingpins are steering arms and brake support extensions. Six bronze bushings ride inside threaded mounts on both ends of three threaded linkage rods. Two connect each wheel to a central pivoting lever system, the third connects the pivot to the under seat handlebar. Gearing is provided by different sized levers on the pivot.

    Wheels are double walled alloy rims laced to alloy hubs via S/S spokes. Front hubs are from a wheelchair, rear hub is a standard five gear bicycle hub.

    Seat is made of three sections, the two sections for back support are shaped to wrap around the torso slightly and include lumbar support. Squab is flat. No padding required due to body hugging nature of the seat.

    Gearing is via a five speed cassette at rear (13-26) operated by standard bicycle derailleur, twin chain wheel at front (52/42) operated by standard front derailleur, and three intermediate gears mid cycle operated by a modified front derailleur. Rear chain is approximately 2.5 lengths and routed through two idler wheels. Front chain is standard length and tensioned by a modified rear derailleur. Intermediate cluster is a modified four ring cassette and is mounted on a bottom bracket bearing retainer and threaded into a shortened bottom bracket welded to main frame.

    Homemade bar end shifters mounted on top, each side of U shaped handlebar service front and rear derailleurs and a modified front deraillleur mounted in front of the seat squab services the intermediate cluster

    Front brakes are modified alloy side pulls operated by alloy levers. No rear brakes required.

    Features and specifications
    Ackerman steering
    Centrepoint steering
    Adjustable toe in
    Geared steering
    Bar end shifters
    Side pull brakes
    Weight 22kgs
    length 1800mm
    Width 780mm
    Height 600mm
    Track 740mm
    Wheelbase 980mm
    Seat height 150mm
    Ground clearance 90mm (Frame) 50-60mm intermediate cassette
    Gears 5 rear
    2 front
    3 intermediate
    Wheels 20

    Kilometers. Lots, used this one for around 8-10 years riding around 20klm 4-5 times per week. Front chain ring and intermediate cassette now worn out and slipping. Unfortunately I can no longer ride this trike and probably never will again due to crook hips. The trike now quietly hangs from the shed ceiling, slowly gathering dust.

    Recumbent bikes. I also made two short wheel base recumbent bikes, 20 front wheel and 27 rear wheel, Both had standard 5 speed cassettes at rear, 52/42 chainrings at front as well as an intermediate cassette mid way to raise the gearing. Unfortunately, chains kept coming off and the intermediate cassette made it very uncomfortable. But, in tests these things, due to their light weight and very high gearing, were incredibly quick.

    Recumbents were banned from racing under the UCI in 1934 due to their superior speed.
    Attached Images Attached Images
    Sit down comedian.

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  3. #2
    Join Date
    Mar 2013
    Location
    Tasmania
    Posts
    393

    Default

    Pretty impressive bike & specs.

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