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Tadpole Trike

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th62

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I’d 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.
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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.

Things have changed a little over the last couple of years, namely I have contracted PsA and largely lost the use of my hands and arms so an MTB is out of the question as I can't take any weight on my wrists. On the plus side, I now have a new hip so can ride recumbents again, and wouldn't you know it, I finaly pulled the taddy from the ceiling and threw it away some months ago, grrrr.

Anyway, I built a two wheeler only to find I keep falling off due to the PsA, almost finished it just needed paint. Now it's in the rubbish. New on the bench is another tadpole, my fifth. This one will sport:

deore components throughout,
20" wheels at front,
700c at rear,
9 speeds at rear,
three speeds at front,
hydraulic disks at front, none required at rear,
Ackerman and centrepoint,
110 wheelbase,
780 track,
frame of 30mm square tubing.

I have all the parts, compliments of the MTB I can't ride anymore and have made most of the parts for the frame, just need to stick it together.

In case you are wondering PsA is psoriatic arthritis, it is an autoimmune disease that eats away your joints, muscles, tendons and inner organs. so far I've had my right hip replaced and right lung removed due to cancer brought on by PsA. Nothing is left of my elbows so an arthroscopy is out of the question, only a total elbow replacement is left, but, Docs not keen on that since I'm only 68. With elbow replacements comes a totally sedentary lifestyle, can't lift anymore than a bag of sugar. Not ready for that yet so I live on pain killers, just wish they would work.

And No, your arthritis is nothing like PsA, PsA is the most serious and disfiguring of the rheumatoids; unfortunately, mine is untreatable. Cancer has returned and is now in my lymph gland, the lymph glands are like a super highway for cancer, radio therapy is not an option so not looking too good at the moment.

Some pics, first pic is of the last one I made and used for 10 years. Other pics are of forerunners, working out gears, seat angle, steering gearing, wheel sizes, steering type, caster, camber, toe in, ride height and so on.

I should point out that the tyres, chain, rims and S/S spokes were bought new, all other parts were found at the rubbish tip or by the side of the road, The alloy components were all mirror polished in my workshop to make them look nice. Phosphor bronze bearings in the steering linkages were all turned up on my lathe, frame was stuck together with a stick and the seat was made of ply bent and moulded to match the contours of my back.

The co=pilot was Dennis, Dennis loved going for rides, so much so he used to scream if I tried to go without hime. Same applied to Toby, the chihuahua we had prior to finding Dennis. Dennis contracted alzheimers and so w had to put him down and Toby died of cancer. When this latest trike is finished I hope to introduce Alice to the world of cycling. Toby was a thrill seeker, no matter how fast I went he would push me to go faster by pawing me and sticking his nose in my ear, as I went faster his ears would go back, he would rest his head on my shoulder and adopt a more streamlined position. Unfortunately, I came off the MTB one day with Dennis on the back, he suffered shock and a few bruises and refused to go with me anymore.

My new recumbent is taking shape: the frame is all tacked together, I've turned up twp stub axles with quick release levers, some delrin bushes for the king pins, a few delrin chain guides and ordered two disk brake hubs from the local bike shop. Still have to make up some under seat bars, steering linkage bearings and seat.
 

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