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T O P I C    R E V I E W
ShelGame Posted - 11/07/2017 : 14:22:14
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...
24   L A T E S T    R E P L I E S    (Newest First)
ShelGame Posted - 12/03/2017 : 16:35:26
Painted the fork and installed it today. Mounted up the wheels just to get a look of it...

ShelGame Posted - 12/03/2017 : 08:23:57
Paint is done. Not pro, but decent for rattle can. I used the same epoxy paint as my long wheelbase home build.



And, re-assembly started.



Friday nigh, I also brazed a brake tab onto the steel Sun fork I plan to use. This thing is not light. But, itís a low rise Ďtrackí fork which is what I laid out for the bike with the 700c wheels. A Ďnormalí height 700c fork and the steering geometry would be all wrong, I think.

ShelGame Posted - 11/28/2017 : 12:32:52
Powdercoat is all off. It's just about ready for re-paint (or re-coat). What does powedercoat usually run?

warren Posted - 11/22/2017 : 08:54:37
Thatís not paint, itís powder coating. Yes it is much tougher than paint!
Speedbiker Posted - 11/21/2017 : 21:19:11
Yeah, overlap. I see it doesn't have much, but I mostly based it on a Vendetta's original geometry. I would have loved to make the whole thing lower, but that wasn't the deal.
ShelGame Posted - 11/21/2017 : 20:29:24
quote:
Originally posted by Speedbiker

Yes Rob, that mbb is the design & prototype I sold Cruzbike(also the one Oslund used for the 100 mile record). It's a good layout, but the boom is too short for non-mbb.




Iím not following. Why is the boom too short for non-MBB? Crank overlap? I would think a short boom would be good, less flex and all that.
Speedbiker Posted - 11/21/2017 : 20:21:07
Yes Rob, that mbb is the design & prototype I sold Cruzbike(also the one Oslund used for the 100 mile record). It's a good layout, but the boom is too short for non-mbb.
ShelGame Posted - 11/21/2017 : 20:06:44
Pringle is in...



Now I just have to figure out how to get the rest of the paint off. Whatever Rans used, itís good stuff. Automotive Paint Stripper hardly even softens it...
warren Posted - 11/16/2017 : 09:55:09
LOL
alevand Posted - 11/16/2017 : 06:43:54
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
warren Posted - 11/15/2017 : 11:47:06
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.
purplepeopledesign Posted - 11/15/2017 : 10:57:52
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/
warren Posted - 11/15/2017 : 08:10:29
Your latest drawing looks great, Rob. Pringle, LOL.
ShelGame Posted - 11/14/2017 : 20:19:00
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.



ShelGame Posted - 11/14/2017 : 20:17:15
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...
Speedbiker Posted - 11/08/2017 : 17:29:49
How about something like an M5 chromoly highracer with smaller wheels? Don't copy slow bikes. Copy fast ones!
ShelGame Posted - 11/08/2017 : 15:36:43
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.
Speedbiker Posted - 11/08/2017 : 11:48:43
Oh no! Too many tubes! One curvy tube and one tall cross section aero stay per side.
ShelGame Posted - 11/08/2017 : 08:43:16
Maybe I need to re-visit this sketch instead of a new HR...

ShelGame Posted - 11/08/2017 : 08:22:29
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.
ShelGame Posted - 11/07/2017 : 20:15:18
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.



Iím not sure theyíre optimized for racing. Theyíre 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 Ďstickí.

I actually have a Rans F5 frame to build up. I may never build this bike...
CincyRay Posted - 11/07/2017 : 17:57:24
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.
ShelGame Posted - 11/07/2017 : 15:53:03
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.
warren Posted - 11/07/2017 : 15:13:03
Are you doing remote steering? Otherwise you must have very long arms. :)

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