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ShelGame
recumbent enthusiast

USA
254 Posts

Posted - 11/07/2017 :  14:22:14  Show Profile  Reply with Quote
Time for this bike to get it's own thread. This is just a first sketch. Literally did this last night in a hour before bed. Really just a geometry study at this point. Feel free to poke holes in the idea.



The idea was to see what a high racer would look like with the seat @ 15deg and as short a boom as possible, staying with a 'stick bike' layout.

I have a Rans F5 (steel) frame coming soon. I'll play with that first to see how I like it and probably refine this idea over the next few months...

warren
human power expert

USA
6087 Posts

Posted - 11/07/2017 :  15:13:03  Show Profile  Visit warren's Homepage  Reply with Quote
Are you doing remote steering? Otherwise you must have very long arms. :)
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ShelGame
recumbent enthusiast

USA
254 Posts

Posted - 11/07/2017 :  15:53:03  Show Profile  Reply with Quote
quote:
Originally posted by warren

Are you doing remote steering? Otherwise you must have very long arms. :)



yeah, I think it would need remote steering, or a lot of tiller.
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CincyRay
Starting Member

USA
33 Posts

Posted - 11/07/2017 :  17:57:24  Show Profile  Reply with Quote
Bacchetta, Schlitter and Rans have all figured out similar geometries that optimize the high racer stick bent. I think you will find that shortening the boom and moving the seat so far back will result in sloppy handing with so much body weight above and behind the rear wheel axis and unnecessary crank interference with the front wheel particularly in slow turns. I can drop my Bacchetta seat to near a zero angle if I wanted to, so not sure what you are trying to improve but be different for the sake of being different. Love your first bent design. very sharp.
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ShelGame
recumbent enthusiast

USA
254 Posts

Posted - 11/07/2017 :  20:15:18  Show Profile  Reply with Quote
quote:
Originally posted by CincyRay

Bacchetta, Schlitter and Rans have all figured out similar geometries that optimize the high racer stick bent. I think you will find that shortening the boom and moving the seat so far back will result in sloppy handing with so much body weight above and behind the rear wheel axis and unnecessary crank interference with the front wheel particularly in slow turns. I can drop my Bacchetta seat to near a zero angle if I wanted to, so not sure what you are trying to improve but be different for the sake of being different. Love your first bent design. very sharp.



I’m not sure they’re optimized for racing. They’re general purpose recumbents.

My point for this study was to see what a low seat angle high racer might look like if I tried to keep the front boom short; and keep the main frame as a ‘stick’.

I actually have a Rans F5 frame to build up. I may never build this bike...
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ShelGame
recumbent enthusiast

USA
254 Posts

Posted - 11/08/2017 :  08:22:29  Show Profile  Reply with Quote
OK, so worked on the F5 frame a bit last night.

It's a 'regular' size frame, ~44" wheelbase. I measured the frame and drew it up in CAD to see what fork I would need to use with it to get decent trail; and see where the seating position might be.

It also has a short boom (12"), with the short wheelbase, this puts the top of the seat ~2" behind the rear axle CL @ 25deg seat back angle. Lowering the seat further seems out of the question. Other dimensions are similar to my sketch above.

Actually, it's pretty similar to the ActionBent HR that I have - with the exception that the WB on that bike is even shorter (38"), and the front boom even longer (and lower BB).

So, this F5 will be a good training bike. But, not an all-out race bike.

Edited by - ShelGame on 11/08/2017 08:42:26
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ShelGame
recumbent enthusiast

USA
254 Posts

Posted - 11/08/2017 :  08:43:16  Show Profile  Reply with Quote
Maybe I need to re-visit this sketch instead of a new HR...

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Speedbiker
human power expert

USA
3744 Posts

Posted - 11/08/2017 :  11:48:43  Show Profile  Reply with Quote
Oh no! Too many tubes! One curvy tube and one tall cross section aero stay per side.
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ShelGame
recumbent enthusiast

USA
254 Posts

Posted - 11/08/2017 :  15:36:43  Show Profile  Reply with Quote
Yeah, too many.

Front wheel is too small.

Maybe something more like this:



Just a slight bend at the rear chain stay attachement. Even lower seat than my first sketch. Still simple.
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Speedbiker
human power expert

USA
3744 Posts

Posted - 11/08/2017 :  17:29:49  Show Profile  Reply with Quote
How about something like an M5 chromoly highracer with smaller wheels? Don't copy slow bikes. Copy fast ones!
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ShelGame
recumbent enthusiast

USA
254 Posts

Posted - 11/14/2017 :  20:17:15  Show Profile  Reply with Quote
How about this?



Inspriation was this:



Which I beleive I read was your work, Thom? Don't know if it was fast, but it looks fast.

Mine is a similar layout, but not FWD...

Edited by - ShelGame on 11/14/2017 20:20:24
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ShelGame
recumbent enthusiast

USA
254 Posts

Posted - 11/14/2017 :  20:19:00  Show Profile  Reply with Quote
At any rate, I'm starting out with this Rans F5 to see what I like and don't like about HR's. Measured the frame, and 'installed' the steel 700c fork I have laying around.



The frame will have to be modified as it was originally a 26/650B frame. I cut the rear frame to fit, and made a 'pringle' to re-close the main boom. I also cut down the HT ~3/4" to lower the front end back down where it should be.

As soon as it warms up enough for the paint stripper to work, I'll strip this frame down and braze in the pringle.




Edited by - ShelGame on 11/14/2017 20:30:32
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warren
human power expert

USA
6087 Posts

Posted - 11/15/2017 :  08:10:29  Show Profile  Visit warren's Homepage  Reply with Quote
Your latest drawing looks great, Rob. Pringle, LOL.
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purplepeopledesign
recumbent guru

Canada
680 Posts

Posted - 11/15/2017 :  10:57:52  Show Profile  Reply with Quote
Just realized that it has to be a Pringle, since a potato chip on a bike means something much less benign.

:)ensen.

Those who claim to be making history are often the same ones repeating it.

Video of my trike
http://www.youtube.com/watch?v=MdSLRD_2vzc
Photos of my trike
http://www.flickr.com/photos/purplepeople/
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warren
human power expert

USA
6087 Posts

Posted - 11/15/2017 :  11:47:06  Show Profile  Visit warren's Homepage  Reply with Quote
I have an old Giro frame with a crack in the base of one of the rear stays which I'm planning on Z-ing. It will have wide tires and headers and be FWD.
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alevand
human power expert

USA
2908 Posts

Posted - 11/16/2017 :  06:43:54  Show Profile  Visit alevand's Homepage  Reply with Quote
Don't do any headers without a helmet on. I use to store my pump inside the tube, until I forgot and sawed it in half.

C:
Tony Levand
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warren
human power expert

USA
6087 Posts

Posted - 11/16/2017 :  09:55:09  Show Profile  Visit warren's Homepage  Reply with Quote
LOL
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