Member-Ken's Experimental Bikes
The Mantis described below, is no more. It has been cut up for parts for a lowracer.
“Black Betty”
My curent bike is called “Black Betty”. She was seen at last years Broadford with an experimental aero-fork. The trailing blade fork has been altered since then to try and get some trail as last year it was negative when the bike was loaded. It is (and always was) very stable at speed. I have also built a “Peter Heal” style tailbox which attaches directly to the seat. The seat still has its rear leaf spring hidden inside the box and the ventilation airscoop still works. The geometry is the same as Mantis but with a 406 rear wheel to make a more compact package. This also allowed more recline for the seat, now somewhere near 35 Deg.
There is a novel chainguard which protects the rings without protruding past them. I still have the mould for this guard, so if someone wanted one, they should talk to me (e-mail address below). One warning, I make things from interest and not for production. Also the streamliner project takes priority at the moment.
“Mantis”
This bike is my second frame. The first one was a city bike conversion built to see if I liked recumbents. It worked quite well and served as the test-bed for the intermediate drive set-up.
“Mantis” was designed with a longer wheelbase (1050 mm)to improve the ride and improve the stability at higher speeds. The frame is made from a length of 35mm square steel tube. This only requires two perpendicular holes to be drilled (32 mm at head tube, and 40 mm at the rear triangle attachment)
A variety of stable configurations have been tested including 16/20, 20/20, and 26/20 with and without front suspension. At Broadford I also used my home-made 700c carbon/nomex rear wheel.The above photo is with carbon wheel attached.
I don’t weld or braise so I would like to thank the following people:-
My Dad for stick welding, Terry Rosewarne-mig welding, Gordon Griffiths-Beautiful braising, Rod Sweeting for “rough” braising, And for general information, everyone in the HPV community!!!!!!!!Particular thanks to Steve Nurse for the 35mm tube methods and to Peter Holloway (Cycle Science) for finding odd parts that solved several problems.
Keep watch whenever I make some of a ride (I usually cannot cope with a full one) as the bike is always changing. It is currently in 16/20 configuration with disc covers on both wheels and flip steering. Photo below shows 20/20 with 16” (305) wheel in front showing thermoformed clear PVC wheel cover.
The fibreglass leaf-spring at the back of the seat gives about 15mm of travel vertically with no flex under pedal stroke pressure. This got awarded best innovation in a homebuilt bike at Broadford (even though James Friday’s commuter was easily the best home-built there). Photo of spring is below.
The photo below taken in Canberra shows the current form of the seat and also the “Sungold” frame that was considered unpainted by the Broadford judges. The suspension is a conversion from 559 to 406 achieved by bonding extra drop-outs to the outside of the reversed fork tubes. You can click here to e-mail me.
