Home Built Bent

[Cyphus]

Hi people,

I've been riding my home built bent for 3 weeks now (love it). Have a
web site up at:
http://home.htva.net/~brisbois/recumbents/stageone/
Thanks to the people that fielded my questions during the build
process. Feedback appreciated (be nice).
Now for yet another question. Any thoughts on using lightweight
aircraft chromoly steel tubing for a frame then wrapping it in a single
layer of carbon fiber (I think my next one's going to be a trike after
reading about "leg suck").

Thanks,

 

[Jeff Wills]

Cyphus wrote:
> Hi people,

Hi, yerself.

> Now for yet another question. Any thoughts on using lightweight
> aircraft chromoly steel tubing for a frame then wrapping it in a single
> layer of carbon fiber

Sure, you could do that. But what are you trying to accomplish? Any
Cro-mo tubing that is thick enough to be welded is adequately stiff for
most recumbent applications. A single layer of carbon won't do much,
either, beyond being really tough to keep it stuck to the tubing. It'd
be better to weld up the frame and then weld in gussets at the
high-stress points.

On the other hand, I've seen a few recumbents built from carbon-wrapped
*aluminum* tubing. Here's one that raced at PIR a couple years ago:
http://www.ohpv.org/pir2003/the-pits/pages/don103.htm

Jeff

 

[Cyphus]

Oh, and thanks for the "*aluminum*" link.

 

[Jeff Wills]

Cyphus wrote:
> > Sure, you could do that. But what are you trying to accomplish?
>
> Possibly an alternative to paint or powdercoating. Not looking for
> stiffness or strength.

Oooohh... now I get it. It's just for cosmetics. You'd still have to
primer the frame with something to avoid galvanic corrosion, though.

If you just want it to *look* like carbon fiber, why not get some Avery
vinyl:
http://www.beacongraphics.com/carbonfiber.html
???

Jeff

 

[Cyphus]

Jeff Wills wrote:
>
> Cyphus wrote:
>
>>>Sure, you could do that. But what are you trying to accomplish?
>>
>> Possibly an alternative to paint or powdercoating. Not looking for
>>stiffness or strength.
>
>
> Oooohh... now I get it. It's just for cosmetics. You'd still have to
> primer the frame with something to avoid galvanic corrosion, though.
>
> If you just want it to *look* like carbon fiber, why not get some Avery
> vinyl:
> http://www.beacongraphics.com/carbonfiber.html
> ???
>
> Jeff
>
Not for cosmetics, but as a protectant. I'm not too concerned with
what it looks like as long as it sticks and stops the underlying metal
from rusting.

 

[Jeff Wills]

Cyphus wrote:

> >
> Not for cosmetics, but as a protectant. I'm not too concerned with
> what it looks like as long as it sticks and stops the underlying metal
> from rusting.

OK, then you're still better off with paint. Carbon fiber is
conductive, and there can be a tiny current flow between the the carbon
and the steel. This causes galvanic corrosion.

I'm not sure if it would be a huge problem with steel, but early Vitus
carbon-tube frames (molded carbon fiber tubes bonded to aluminum lugs)
experienced many frame failures due to galvanic corrosion. They fixed
this by inserting a layer of fiberglass between the lug and tube.
Fiberglass is an insulator.

On the other hand, I've seen a number of steel bikes that have gone
years *without* paint- and they're still intact and relatively rust
free. Usually they're owned by Joe Kochanowski:
http://www.ohpv.org/pir2003/joekoch/pages/don041.htm .

If all you're concerned with is rust prevention, a can or two of epoxy
spray paint is easier and cheaper than sheathing the frame in carbon
fiber.

Jeff

 

[Bob Parnass]

On Wed, 15 Jun 2005 10:56:07 -0400, Cyphus wrote:

> I've been riding my home built bent for 3 weeks now (love it). Have a
> web site up at:
> http://home.htva.net/~brisbois/recumbents/stageone/

Nice web site! Thanks for documenting your work and
sharing the info.

--
=========================================================================
Bob Parnass, AJ9S GNU/Linux User http://parnass.com