Should I be afraid of carbon?

[Chalo]

Threeducks <[email protected]> wrote:
>
> Chalo wrote:
> > Werehatrack <[email protected]> wrote:
> >
> >>[email protected] wrote:
> >>
> >>>One possible complication is that circuit boards, unlike
> >>>bike frames, are affected by lots of local hot spots.
> >>
> >>Some are also exposed to significant levels of ozone, and yet seem
> >>unaffected.
> >
> > Another variable is UV radiation, which bikes get a lot of while
> > circuit boards generally don't.
>
> Who rides an unpainted bicycle? And if UV radiation is a problem, it is
> a simple matter to block it with a coating.

Lots of CFRP bikes are clearcoated, not painted. Besides, we are
discussing potential longevity, and any paint or coating can
deteriorate in less than the time span in question. That a coat of
paint can forestall UV damage for a few years does not make the issue
disappear-- if UV can damage CFRP, then that would put some limit on
how long a CFRP bike can last, at least if it's ridden outdoors by
daylight.

Chalo Colina

 

[foldedpath]

[email protected] (Chalo) wrote in
news:[email protected]:

> Threeducks <[email protected]> wrote:
>>
>> Who rides an unpainted bicycle? And if UV radiation is a problem, it
>> is a simple matter to block it with a coating.
>
> Lots of CFRP bikes are clearcoated, not painted. Besides, we are
> discussing potential longevity, and any paint or coating can
> deteriorate in less than the time span in question. That a coat of
> paint can forestall UV damage for a few years does not make the issue
> disappear-- if UV can damage CFRP, then that would put some limit on
> how long a CFRP bike can last, at least if it's ridden outdoors by
> daylight.

I'm no expert on CFRP bikes, but I know a few things about boats.
Someone earlier mentioned that fiberglass boats last a long time, but
boats are usually coated with a thick "gel coat" that forms a secondary
protective layer over the resin/cloth matrix.

The boats that are most like bicycles are canoes and kayaks. My SO and I
currently own three sea kayaks, two in fiberglass and one in kevlar.
These boats are all 10 to 15 years old. Because the gel coat is still in
reasonably good shape on all these boats (if somewhat scarred and
chalky), the underlying resin/cloth matrix is fine.

OTOH, I once had a racing sea kayak in kevlar, with a clear resin coat
(no gel coat), that didn't last long. After just 3 years in the South
Florida sun, the resin started to break down. Instead of a smooth
"glass" surface, the fibers were starting to poke through, and the hull
started to show a lot of hairline stress cracks. So there is a limit,
especially with clear resins and finishes that show the underlying fiber
matrix. I thought the "clear/golden Kevlar" look was cool when I first
bought the kayak, but not after it started to fall apart on me after
just a few years.

I wouldn't worry about this in places like the Pacific Northwest, where
not only is there less total yearly UV from sunshine, but it's at a much
lower angle (more filtered by the atmosphere). But in places like
Florida, Arizona, or California at lower lattitudes, it could be a
problem. Speaking only for myself, if I was sinking a lot of money in a
carbon bike, I'd have it painted with something that was guaranteed to
block UV.

--
Mike Barrs

 

[David L. Johnson]

On Thu, 26 Aug 2004 15:29:45 -0700, Chalo wrote:


> Lots of CFRP bikes are clearcoated, not painted.

A clearcoat will offer some UV protection.

> disappear-- if UV can damage CFRP, then that would put some limit on
> how long a CFRP bike can last, at least if it's ridden outdoors by
> daylight.

Unless the bike is stored outdoors in the sun, I doubt that the UV
exposure would be enough to cause damage for many years. UV also damages
the plastics used in cable sheaths, the materials in saddles, and tires.
But few bikes really have a problem because of UV damage to these parts.

--

David L. Johnson

__o | Arguing with an engineer is like mud wrestling with a pig... You
_`\(,_ | soon find out the pig likes it!
(_)/ (_) |

 

[foldedpath]

"Trevor" <[email protected]> wrote in news:cgloml$9nr$7$8300dec7
@news.beeb.net:

> Stresses made upon a boat hull are much different than that made upon a
> bicycle frame.

Not vastly different, if you get into human-powered boats like CFRP canoes,
rowing shells, and kayaks. They race those too, 'ya know. The racing
versions all live on the bleeding edge between being just barely strong
enough not to fall apart, and being as light as possible. Speed in the
water for a displacement hull is limited by hull length. So you have to
make 'em long, as well as narrow and lightweight. It's an interesting
design problem... just like bicycles.

--
Mike Barrs

 

[Threeducks]

Chalo wrote:
> Threeducks <[email protected]> wrote:
>
>>Chalo wrote:
>>
>>>Werehatrack <[email protected]> wrote:
>>>
>>>
>>>>[email protected] wrote:
>>>>
>>>>
>>>>>One possible complication is that circuit boards, unlike
>>>>>bike frames, are affected by lots of local hot spots.
>>>>
>>>>Some are also exposed to significant levels of ozone, and yet seem
>>>>unaffected.
>>>
>>>Another variable is UV radiation, which bikes get a lot of while
>>>circuit boards generally don't.
>>
>>Who rides an unpainted bicycle? And if UV radiation is a problem, it is
>>a simple matter to block it with a coating.
>
>
> Lots of CFRP bikes are clearcoated, not painted.

Then UV radiation must not be an issue then.

> Besides, we are
> discussing potential longevity, and any paint or coating can
> deteriorate in less than the time span in question.

I have a 10 year old bike and the paint is perfect.

> That a coat of
> paint can forestall UV damage for a few years does not make the issue
> disappear-- if UV can damage CFRP, then that would put some limit on
> how long a CFRP bike can last, at least if it's ridden outdoors by
> daylight.

Steel can rust, which would lead to failure. What's your point?

 

[Trevor]

David L. Johnson wrote in message ...
>On Thu, 26 Aug 2004 15:29:45 -0700, Chalo wrote:
>
>
>> Lots of CFRP bikes are clearcoated, not painted.
>
>A clearcoat will offer some UV protection.
>
>> disappear-- if UV can damage CFRP, then that would put some limit on
>> how long a CFRP bike can last, at least if it's ridden outdoors by
>> daylight.
>
>Unless the bike is stored outdoors in the sun, I doubt that the UV
>exposure would be enough to cause damage for many years. UV also damages
>the plastics used in cable sheaths, the materials in saddles, and tires.
>But few bikes really have a problem because of UV damage to these parts.
>
>--
The UV damaged caused in these items is not critical. Sudden failure will
not happen. failure is progressive and of minor consequence.

Trevor

 

[Trevor]

foldedpath wrote in message ...
>"Trevor" <[email protected]> wrote in news:cgloml$9nr$7$8300dec7
>@news.beeb.net:
>
>> Stresses made upon a boat hull are much different than that made upon a
>> bicycle frame.
>
>Not vastly different, if you get into human-powered boats like CFRP canoes,
>rowing shells, and kayaks. They race those too, 'ya know. The racing
>versions all live on the bleeding edge between being just barely strong
>enough not to fall apart, and being as light as possible. Speed in the
>water for a displacement hull is limited by hull length. So you have to
>make 'em long, as well as narrow and lightweight. It's an interesting
>design problem... just like bicycles.
>
>--
I expect that these racing hulls are replaced as a matter of course after a
season and so their typical usage is not similar to a cyclist who may want
to ride the same frame for ten years or more. UV radiation is important and
gel coats are required to protect the integrity of the material.

Trevor

 

[foldedpath]

Bonehenge <[email protected]> wrote in
news:[email protected]:

> Calfee and Giant don't seem to be afraid of uncoated carbon. Calfee
> offers a 25 year frame warranty, Giant is lifetime. Both offer raw,
> uncoated, carbon frames.
>
> Barry

Here's what Calfee says about that on the web site (white paper link):

"One thing that paint does well is to protect the epoxy from ultra-violet
rays. Clearcoats that filter UV rays are commonly available however. On a
clearcoated frame, it is much harder to hide manufacturing defects. Non-
coated frames can be protected from UV with wipe on, wipe off products such
as 303 ProtectantSM."

I think you just have to apply some smarts about your local conditions. I
wouldn't worry about a clearcoat carbon bike in Seattle, but I'd feel more
comfortable choosing one of Calfee's painted carbon frame options for
riding in a place like in Miami. I wouldn't personally trust a "UV
filtering" cleacoat, much less a UV wax finish in an area with fairly high
UV index, since I've seen too many clear epoxy products break down under
those conditions.

--
Mike Barrs

 

[Douglas Landau]

"Trevor" <[email protected]> wrote in message news:<[email protected]>...
>
> >Not vastly different, if you get into human-powered boats like CFRP canoes,
> >rowing shells, and kayaks. They race those too, 'ya know. The racing
> >versions all live on the bleeding edge between being just barely strong
> >enough not to fall apart, and being as light as possible. Speed in the
> >water for a displacement hull is limited by hull length. So you have to
> >make 'em long, as well as narrow and lightweight. It's an interesting
> >design problem... just like bicycles.
> >
> >--
> I expect that these racing hulls are replaced as a matter of course after a
> season and so their typical usage is not similar to a cyclist who may want
> to ride the same frame for ten years or more. UV radiation is important and
> gel coats are required to protect the integrity of the material.

Oh sure! All rowers have $$$ for a new scull every year. Just like all
cyclists have $$$ for a new trek 5900 each year.

I'd love to get a new scull just once -- let alone every year -- but I don't
have 5-7K to spend. So I'm still rowing my kevlar-skinned 84 Van Dusen.

Doug