Riding with a cracked CF handlebar

[jspa...@linuxquestions.net]

How safe is it to ride with a cracked carbon fibre road handlebar?

This evening I went for a ride and ran over a small bump in the road while I was up out of the saddle with some of my weight on the tops of my bars. I heard a cracking sound and felt a splinter in my finger.

I stopped to take a look and discovered that I had a small crack on the right underside of my FSA K-Wing handlebar. It's not around the stem. It appears to be around the opening where the brake cables go into.

The bar itself is around 6 years old. The bump I ran over wasn't that harsh, so maybe it was a combination of my weight on it and age/fatigue of the bar.

Anyways, is the handlebar still safe to ride on? It doesn't flex when I put weight on it, but I don't want it to snap off completely while I'm out riding and putting stress on it.


Thanks,
J. Spaceman

[Dan O]

On Aug 16, 7:36 pm, jspace...@linuxquestions.net wrote:
> How safe is it to ride with a cracked carbon fibre road handlebar?
>

No less safe than riding with one or no hands - I do it all the time
no problem.

> This evening I went for a ride and ran over a small bump in the road while I was up out of the saddle with some of my weight on the tops of my bars. I heard a cracking sound and felt a splinter in my finger.
>
> I stopped to take a look and discovered that I had a small crack on the right underside of my FSA K-Wing handlebar. It's not around the stem. It appears to be around the opening where the brake cables go into.
>
> The bar itself is around 6 years old. The bump I ran over wasn't that harsh, so maybe it was a combination of my weight on it and age/fatigue of the bar.
>
> Anyways, is the handlebar still safe to ride on? It doesn't flex when I put weight on it, but I don't want it to snap off completely while I'm out riding and putting stress on it.
>

Don't ride it hard. I wouldn't put any weight on the broken side at
all unless I was prepared to catch myself. I'd replace the
handlebars.

[James]

I would be nervous riding "normally". If you had to ride it to the LBS,
take care not to load that side. It could let go without warning. This
happened to a friend not so long ago. If you're heaving on the bars at
the time, you may well have a spill.

Replace ASAP, and watch for more splinters. Sometimes the crack
propagates and has nasty sharp edges.

--
JS.

[Frank Krygowski]

I'd like to see photos, but failure of a handlebar is scary indeed.
Contrary to some opinions, there would probably be zero chance of
"catching" yourself if it fails suddenly. Your weight on only one side
would likely throw the front wheel sideways and send you right over the
remainder of the bars.

One of my friends had a fancy aluminum handlebar fail at very low speed.
It was a sudden fracture caused by stress concentration at a hole
through which a cable passed. I don't know what the hospital trip cost
him, but it wasn't cheap.

--
- Frank Krygowski

[Jay Beattie]

On Aug 16, 7:36 pm, jspace...@linuxquestions.net wrote:

I have those bars. If they cracked, I would replace them
immediately. I've had bars break -- some Cinelli aluminum bars. They
failed on my way to work, deforming first and then breaking. I had
time to bring the bike to a stop With CF, you could end up with a
sudden failure, although I don't think it would be as catastrophic as
Frank's friend, but still not fun. -- Jay Beattie.

[Dan O]

On Aug 16, 8:45 pm, Frank Krygowski <frkrygowREM...@gEEmail.com>
wrote:

> jspace...@linuxquestions.net wrote:
> > How safe is it to ride with a cracked carbon fibre road handlebar?
>
> > This evening I went for a ride and ran over a small bump in the road while I was up out of the saddle with some of my weight on the tops of my bars. I heard a cracking sound and felt a splinter in my finger.
>
> > I stopped to take a look and discovered that I had a small crack on the right underside of my FSA K-Wing handlebar. It's not around the stem. It appears to be around the opening where the brake cables go into.
>
> > The bar itself is around 6 years old. The bump I ran over wasn't that harsh, so maybe it was a combination of my weight on it and age/fatigue of the bar.
>
> > Anyways, is the handlebar still safe to ride on? It doesn't flex when I put weight on it, but I don't want it to snap off completely while I'm out riding and putting stress on it.
>
> > Thanks,
> > J. Spaceman
>
> I'd like to see photos, but failure of a handlebar is scary indeed.
> Contrary to some opinions, there would probably be zero chance of
> "catching" yourself if it fails suddenly. Your weight on only one side
> would likely throw the front wheel sideways and send you right over the
> remainder of the bars.
>

As if you would know.

http://groups.google.com/group/rec.bicycles.tech/msg/1351c07fff3586e1

> One of my friends had a fancy aluminum handlebar fail at very low speed.
> It was a sudden fracture caused by stress concentration at a hole
> through which a cable passed. I don't know what the hospital trip cost
> him, but it wasn't cheap.
>

DANGER! DANGER!

[Jeff Liebermann]

On Thu, 16 Aug 2012 19:36:41 -0700 (PDT), jspa...@linuxquestions.net
wrote:

>How safe is it to ride with a cracked carbon fibre road handlebar?

I don't know, but I wouldn't risk it if it were my bicycle.

If you insist on riding it while waiting for a replacement, I suggest
you build a splint around the broken area. Two pieces of aluminum or
steel "L" channel held in place with some automotive hose clamps. Put
pieces of old inner tube rubber under the channels and clamps to keep
from trashing the CF. Since it's not around the stem, there will
probably be room for the splint. Yes, it's ugly, not aero, heavy, but
just might delay a catastrophic failure.

Also, are you sure it's a real KSA bar or a fake?
<http://www.youtube.com/watch?v=CyK-VbkBmqQ>
<http://www.youtube.com/watch?v=ewB7Qd5HEGM>
<http://www.youtube.com/watch?v=uxjWEqCwyYU>
You'll need a UV LED flashlight.

--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

[James]

On 17/08/12 14:54, Dan O wrote:
> On Aug 16, 8:45 pm, Frank Krygowski<frkrygowREM...@gEEmail.com>
> wrote:
>> jspace...@linuxquestions.net wrote:
>>> How safe is it to ride with a cracked carbon fibre road handlebar?
>>
>>> This evening I went for a ride and ran over a small bump in the road while I was up out of the saddle with some of my weight on the tops of my bars. I heard a cracking sound and felt a splinter in my finger.
>>
>>> I stopped to take a look and discovered that I had a small crack on the right underside of my FSA K-Wing handlebar. It's not around the stem. It appears to be around the opening where the brake cables go into.
>>
>>> The bar itself is around 6 years old. The bump I ran over wasn't that harsh, so maybe it was a combination of my weight on it and age/fatigue of the bar.
>>
>>> Anyways, is the handlebar still safe to ride on? It doesn't flex when I put weight on it, but I don't want it to snap off completely while I'm out riding and putting stress on it.
>>
>>> Thanks,
>>> J. Spaceman
>>
>> I'd like to see photos, but failure of a handlebar is scary indeed.
>> Contrary to some opinions, there would probably be zero chance of
>> "catching" yourself if it fails suddenly. Your weight on only one side
>> would likely throw the front wheel sideways and send you right over the
>> remainder of the bars.
>>
>
> As if you would know.
>
> http://groups.google.com/group/rec.bicycles.tech/msg/1351c07fff3586e1

Agreed. I had half the bars break off next to the clamp near the end of
a longish road race. 10 km to go and I finished with the break, even
chased down an escapee coming in to town. I didn't crash. I know my
bro has broken bars at least twice and didn't crash. A friend had CF
bars break more recently and he didn't crash. Jay has broken bars and
not crashed. You've done it. While I would not recommend using the
cracked bars for normal service as a crash is quite possible, Frank is
clearly talking out his arse, as many have survived his zero chance outcome.

>> One of my friends had a fancy aluminum handlebar fail at very low speed.
>> It was a sudden fracture caused by stress concentration at a hole
>> through which a cable passed. I don't know what the hospital trip cost
>> him, but it wasn't cheap.
>>
>
> DANGER! DANGER!
>

Quite.

(Broke a spoke last night. 20 km to home on a 23 spoke wheel. One of
the LHS spokes, of which there were 8, broke about 2-3 threads into the
nipple. I removed the spoke, opened the brakes and rode home. Had a
spare spoke at home and replaced it last night. Good as new. So much
for the "Can't ride home when you break a spoke in low spoke count
wheels." crew.)

--
JS.

[Lou Holtman]

Op 17-8-2012 7:47, James schreef:

What does this say? I know someone who actually crashed. Broke off three
of his front teeth. Telling the OP just to ride on and be carefull is
stupid (not telling that you do James).
This question shows again that people are reluctant to replace the
handlebar after a crash or whatever caused the damage if they paid
200-300 euro's for that handlebar. If it was a high end aluminum
handlebar of 60-70 euro's they wouldn't asked this question and just
replace it as the OP should do now with his CF handlebar IMO.

Lou

[John B.]

On Thu, 16 Aug 2012 19:36:41 -0700 (PDT), jspa...@linuxquestions.net
wrote:

A carbon fiber reinforced component is immensely strong.... as long as
it maintains its structural integrity, but once cracked its strength
drops dramatically. I would suggest that you either replace or repair
the item

Contrary to what seems to be popular belief reinforced composites can
be repaired and returned to original, or even higher, strength. Below
is the Web Site of a German company that specializes in the work and
I'm sure that there must be firms in the U.S. that do the same sort of
work.

I have a good friend in the business of "fiberglass" repair work on
boats and I've done a certain amount of it myself. It is not rocket
science, nor does it take high priced specialized equipment or, with
the exception of the carbon cloth itself, especially expensive
supplies.

http://polytube-cycles.de/en/index.html
Cheers,
John B.

[Duane]

You need to replace the handle bar.

[Duane]

On 08/16/2012 10:45 PM, Dan O wrote:
> On Aug 16, 7:36 pm, jspace...@linuxquestions.net wrote:
>> How safe is it to ride with a cracked carbon fibre road handlebar?
>>
>
> No less safe than riding with one or no hands - I do it all the time
> no problem.

It's one thing to ride intentionally with no hands. It's another thing
to be riding normally and then find yourself riding with one hand.

>> This evening I went for a ride and ran over a small bump in the road while I was up out of the saddle with some of my weight on the tops of my bars. I heard a cracking sound and felt a splinter in my finger.
>>
>> I stopped to take a look and discovered that I had a small crack on the right underside of my FSA K-Wing handlebar. It's not around the stem. It appears to be around the opening where the brake cables go into.
>>
>> The bar itself is around 6 years old. The bump I ran over wasn't that harsh, so maybe it was a combination of my weight on it and age/fatigue of the bar.
>>
>> Anyways, is the handlebar still safe to ride on? It doesn't flex when I put weight on it, but I don't want it to snap off completely while I'm out riding and putting stress on it.
>>
>
> Don't ride it hard. I wouldn't put any weight on the broken side at
> all unless I was prepared to catch myself. I'd replace the
> handlebars.

Yep. I would replace it immediately. If I had to ride it to the shop,
that would be the extent of my riding before it was replaced.

[Duane]

Been there. Done that. I would still replace a broken handlebar (or
spoke) as soon as possible. In either case, with 20k to get home, I'd
likely go for it but next stop is the shop or ordering a new part.

BTW, what exactly is a "fancy aluminum handlebar?" Is that one of those
that aren't made of rebar?

[DirtRoadie]

On Aug 17, 5:24 am, John B. <johnbsloc...@gmail.com> wrote:
> On Thu, 16 Aug 2012 19:36:41 -0700 (PDT), jspace...@linuxquestions.net

> wrote:
>
> >How safe is it to ride with a cracked carbon fibre road handlebar?
>
> >This evening I went for a ride and ran over a small bump in the road while I was up out of the saddle with some of my weight on the tops of my bars.  I heard a cracking sound and felt a splinter in my finger.
>
> >I stopped to take a look and discovered that I had a small crack on the right underside of my FSA K-Wing handlebar.  It's not around the stem.  It appears to be around the opening where the brake cables go into.
>
> >The bar itself is around 6 years old.  The bump I ran over wasn't that harsh, so maybe it was a combination of my weight on it and age/fatigue of the bar.
>
> >Anyways, is the handlebar still safe to ride on?  It doesn't flex when I put weight on it, but I don't want it to snap off completely while I'm out riding and putting stress on it.
>
> >Thanks,
> >J. Spaceman
>
> A carbon fiber reinforced component is immensely strong.... as long as
> it maintains its structural integrity, but once cracked its strength
> drops dramatically. I would suggest that you either replace or repair
> the item
>
> Contrary to what seems to be popular belief reinforced composites can
> be repaired and returned to original, or even higher, strength. Below
> is the Web  Site of a German company that specializes in the work and
> I'm sure that there must be firms in the U.S. that do the same sort of
> work.
>

http://www.calfeedesign.com/repair/frequently-asked-questions/
Frames, yes, handlebars or forks, no.

DR

[thirty-six]

I think that at six years you should consider it to have probably
outlived its expected lifespan, unless you can find documentary
evidence to the contrary. The failure and its probable
predictability suggest that a carbon-fibre handlebar be inspected
before each racing season under stressed conditions. If you can't or
wont do this or have a professional inspection each season then choose
a metal handlebar or retire a carbon-fibre component early at 2
years. I suggest that if you do replace with a crabon-fibre petro-
polymer handlebar that you are careful in the choice and application
of cable lubricant, bar-tape adhesive and tan-lotions etc used as
anything petroleum derived on long-term contact with the bar, will
cause deterioration in the polymer stability. A cellulose laquer may
be help in providing a suitable barrier to mineral oils and the like
but one would need to be careful as to the solvent in the laquer.

[AMuzi]

It's damaged. Do not ride it.
Replace any damaged handlebar, whatever the material.
Promptly.

--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971

[jspa...@linuxquestions.net]

Thanks for the replies. I'm supposed to do a 100km ride this Sunday, fairly hilly too; which means I'll be out of the saddle and putting weight/stress on the bar.

I thought about taking the bike into the LBS to either buy (if I have the $$$) or see if they can loan me a pair of bars and install them for me.


J. Spaceman

[davethedave]

Do it now! Carbon goes rather suddenly and without warning.

--
davethedave

[Frank Krygowski]

So you rode 10 km with half the handlebar broken off? Did you lash the
broken-off half to your top tube, toss it jauntily over your shoulder,
or just carry it loosely in your hand as you chased down that other
rider? I really am curious about details, James.

> I know my bro
> has broken bars at least twice and didn't crash. A friend had CF bars
> break more recently and he didn't crash. Jay has broken bars and not
> crashed. You've done it. While I would not recommend using the cracked
> bars for normal service as a crash is quite possible, Frank is clearly
> talking out his arse, as many have survived his zero chance outcome.

Note that I said "there would probably be zero chance of 'catching'
yourself _if it fails suddenly._"

But since you're sure it's no problem, you might want to correct all the
other folks who told this guy to replace his bars.


--
- Frank Krygowski

[thirty-six]

On Aug 17, 6:25 pm, Frank Krygowski <frkrygowREM...@gEEmail.com>

The majority of CF bars are not so much lighter than heat-treated
light aluminium alloy. I think that there is some safety margin
built in so that there is some resilience to damage in the event of
the inevitable knocks and tumbles.

>
> But since you're sure it's no problem, you might want to correct all the
> other folks who told this guy to replace his bars.

Personally I might take the chance if I believed I could conduct the
forthcoming ride one-handed, with additional binding. I rode for a
while with a weakened aluminium handlebar and it did give way on me.
It was expected and I was able to respond by stiffening up my other
arm as the bar dropped. Fortunately it did not detatch and get caught
in the spokes. I don't know wether a carbon bar is likely to detatch
when it gives way and I;d need to know that before making a
declaration to another that a failing carbon bar is safe. The fact
that it is already splintering suggests that the risk of becoming
penetrated by such splinters (and highly dangerous they are) be too
high for my liking.

I think the splintering really does suggest that the bar has come to
the end of its life. ^ years is not premature for a light racing
component.

[Jay Beattie]

On Aug 17, 10:25 am, Frank Krygowski <frkrygowREM...@gEEmail.com>
wrote:

It's do-able. http://www.youtube.com/watch?v=9-Pu71HXrfY

>  > I know my bro
>
> > has broken bars at least twice and didn't crash. A friend had CF bars
> > break more recently and he didn't crash. Jay has broken bars and not
> > crashed. You've done it. While I would not recommend using the cracked
> > bars for normal service as a crash is quite possible, Frank is clearly
> > talking out his arse, as many have survived his zero chance outcome.
>
> Note that I said "there would probably be zero chance of 'catching'
> yourself _if it fails suddenly._"
>
> But since you're sure it's no problem, you might want to correct all the
> other folks who told this guy to replace his bars.

He's not recommending against replacing the bars -- only pointing out
that a crash is not certain, even where there is a catastrophic
failure. That is probably true if you're just riding along on the
flats and have good balance. Still . . . replace the bars ASAP!

-- Jay Beattie.

[Dan O]

On Aug 17, 5:38 am, Duane <duane.heb...@group-upc.com> wrote:
> On 08/16/2012 10:45 PM, Dan O wrote:
>
> > On Aug 16, 7:36 pm, jspace...@linuxquestions.net wrote:
> >> How safe is it to ride with a cracked carbon fibre road handlebar?
>
> > No less safe than riding with one or no hands - I do it all the time
> > no problem.
>
> It's one thing to ride intentionally with no hands. It's another thing
> to be riding normally and then find yourself riding with one hand.
>

Well, that's what I meant (I was being flip). If you know the
handlebar is broken, you know you're going to be riding with (at
most), effectively, one hand.

> >> This evening I went for a ride and ran over a small bump in the road while I was up out of the saddle with some of my weight on the tops of my bars. I heard a cracking sound and felt a splinter in my finger.
>
> >> I stopped to take a look and discovered that I had a small crack on the right underside of my FSA K-Wing handlebar. It's not around the stem. It appears to be around the opening where the brake cables go into.
>
> >> The bar itself is around 6 years old. The bump I ran over wasn't that harsh, so maybe it was a combination of my weight on it and age/fatigue of the bar.
>
> >> Anyways, is the handlebar still safe to ride on? It doesn't flex when I put weight on it, but I don't want it to snap off completely while I'm out riding and putting stress on it.
>
> > Don't ride it hard. I wouldn't put any weight on the broken side at
> > all unless I was prepared to catch myself. I'd replace the
> > handlebars.
>
> Yep. I would replace it immediately. If I had to ride it to the shop,
> that would be the extent of my riding before it was replaced.

Effectively, riding one handed (no hands remaining another ~safe
option).

(I probably would we wary of the side that hadn't broken yet, at
that.)

[Dan O]

On Aug 17, 10:25 am, Frank Krygowski <frkrygowREM...@gEEmail.com>
wrote:

Which post in this thread doesn't advise replacing the bars?

[Duane]

Ok. But the OP is talking about starting off on a 100k ride with hills
knowing that the handlebar is broken. I think even the wheeljie king
would advise against that. <g>

[DirtRoadie]

On Aug 17, 11:25 am, Frank Krygowski <frkrygowREM...@gEEmail.com>
wrote:

As all seem to agree

> Frank is clearly
> > talking out his arse, as many have survived his zero chance outcome.
>
> Note that I said "there would probably be zero chance of 'catching'
> yourself _if it fails suddenly._"
>

And you were wrong.
I've watched a racer in a criterium snap one side of his aluminum
handlebars at the stem but still finish the race, albeit well OTB .
BTW the OP was quite clear, "It's not around the stem. It appears to

be around the opening where the brake cables go into."

> But since you're sure it's no problem, you might want to correct all the
> other folks who told this guy to replace his bars.
>
> --
> - Frank Krygowski

Was there someone - a real person - who disagreed with the
recommendation of replacement?
DR

[Joe Riel]

DirtRoadie <DirtR...@aol.com> writes:

> I've watched a racer in a criterium snap one side of his aluminum
> handlebars at the stem but still finish the race, albeit well OTB .

Sanctioned? Shouldn't the officials have pulled him?
Riders get dq'ed fo missing handlebar plugs.

--
Joe Riel

[DirtRoadie]

On Aug 17, 4:13 pm, Joe Riel <j...@san.rr.com> wrote:

Perhaps, but that didn't happen. I was thinking his bike sponsor might
have been a bit unhappy to have its product displayed in a defective
condition for a few laps.
DR

[Frank Krygowski]

Oh. I missed the part where James said he whipped out the tape and
taped the bar down while he rode in the race. My fault.

> Still . . . replace the bars ASAP!

Right!


--
- Frank Krygowski

[DirtRoadie]

On Aug 17, 4:37 pm, Frank Krygowski <frkrygowREM...@gEEmail.com>

> > It's do-able.http://www.youtube.com/watch?v=9-Pu71HXrfY

>
> Oh.  I missed the part where James said he whipped out the tape and
> taped the bar down while he rode in the race.  My fault.

Yes please try to pay attention. The guy that I described in a
criterium rode in essentially the same manner as shown the video,
sans tape, just holding bars together on one side with a hand.
So do you or don't you retract your silly "zero chance of catching
yourself" comment?

DR

[Jay Beattie]

On Aug 17, 3:37 pm, Frank Krygowski <frkrygowREM...@gEEmail.com>

> > It's do-able.http://www.youtube.com/watch?v=9-Pu71HXrfY

>
> Oh.  I missed the part where James said he whipped out the tape and
> taped the bar down while he rode in the race.  My fault.
>
> > Still . . . replace the bars ASAP!
>
> Right!
>
> --
> - Frank Krygowski

Hey Frank, I broke my bars and rode three or so miles to work with no
tape. You just drape the bar and lever over the stem or hold on to
it. It's not magic. You make it sound like James is lying or
something.

You have all of these disaster scenarios going in your head. Sure,
don't ride with broken bars -- everyone agrees, but if your bars
break, you may or may not crash. I've broken pedals, cranks, seat
posts, bars, chains and frames and never crashed. I broke two cranks
riding out of the saddle and didn't crash. I think I broke six
altogether, maybe more. Sometimes when things break, you don't
crash . . . and sometimes you do, and that's why you replace the
bars.

-- Jay Beattie.

[John B.]

You are correct. He says that because of critical dimensional
requirements he doesn't repair handlebars and forks.
Cheers,
John B.

[James]

Please reread. I did not say ride on fearlessly. I said replace ASAP, but if you have to ride to the LBS, be careful not to put weight on the bars. I'm in agreement with you, Lou.

--
JS.

[Joe Riel]

DirtRoadie <DirtR...@aol.com> writes:

>> >>> Agreed. I had half the bars break off next to the clamp near the end of
>> >>> a longish road race. 10 km to go and I finished with the break, even
>> >>> chased down an escapee coming in to town. I didn't crash.
>>
>> >> So you rode 10 km with half the handlebar broken off?  Did you lash the
>> >> broken-off half to your top tube, toss it jauntily over your shoulder,
>> >> or just carry it loosely in your hand as you chased down that other
>> >> rider?  I really am curious about details, James.
>>
>> > It's do-able.http://www.youtube.com/watch?v=9-Pu71HXrfY
>>
>> Oh.  I missed the part where James said he whipped out the tape and
>> taped the bar down while he rode in the race.  My fault.
>
> Yes please try to pay attention. The guy that I described in a
> criterium rode in essentially the same manner as shown the video,
> sans tape, just holding bars together on one side with a hand.
> So do you or don't you retract your silly "zero chance of catching
> yourself" comment?

Ah, but did the bar break suddenly? What is the typical failure mode?
I've broken handlebars near the stem and had to ride home with half a
bar. The initial fracture was on the lower half, the separation occurred
when pulling up on the bars from a stop. Didn't crash.


--
Joe Riel

[James]

Yes, to finish a race.

> Did you lash the
>
> broken-off half to your top tube, toss it jauntily over your shoulder,
>
> or just carry it loosely in your hand as you chased down that other
>
> rider? I really am curious about details, James.

It was still connected via brake and gear cables. It was the RHS that broke at the stem clamp. There was enough free end to move it across to the left and I could hold the end with my fingers of my left hand. I could then still change gears with my right hand and use the front brake, but the left hand was busy holding the bars. I asked the race follow vehicle to grab me a stick so I could insert and brace the bars, but they would not stop to pick up a stick along the country road where we were racing.

--
JS.

[John B.]

You are going pretty far overboard here. What are generally referred
to as "Carbon" bike components are actually carbon fiber - epoxy
composites and epoxy is reasonably impervious to hydrocarbons.
impervious enough that they build both gasoline and diesel fuel tanks
from epoxy. It is extremely doubtful that a small amount of tape glue
or sun tan lotion is going to damage them.

Having said that, the beautiful, shiny finish on some carbon
components isn't a structural part of the component, it is a "clear
coat" and likely is not epoxy resin, although it might be an epoxy
based paint. But on the other hand it might not be and as there is no
way of knowing what a particular manufacturer uses as clear coat I
can't comment on its resistance to mineral oils.

Cheers,
John B.

[thirty-six]

If this pov is prevelant, it should not surprise one that
manufacturers don't bother thinking too hard about the polymer's
resistance to likely contaminents. As long as it passes their quoted
guarantee period, they are happy. Notice that PSA requires one to use
a special assembly paste for them to honour their limited guarantee.
I wonder if they would back down if one used crushed walnut shells and
linseed oil/

>
> Having said that, the beautiful, shiny finish on some carbon
> components isn't a structural part of the component, it is a "clear
> coat" and likely is not epoxy resin, although it might be an epoxy
> based paint. But on the other hand it might not be and as there is no
> way of knowing what a particular manufacturer uses as clear coat I
> can't comment on its resistance to mineral oils.

I think its a specification which should be checked with the supplier
or manufacturer or use only non-petroleum oils and solvents.

[datakoll]

ONE OF THE PROBS WE REAL STEEL TYPES HAVE WITH plastics in general is or are one batch is not the next batch. Quality control for outgoing materials may be close in for specs comparison but then 6 years from now ?

has the bar's color faded ?

https://www.google.com/webhp?hl=en&tab=gw&q=Search%20for%20topics#hl=en&sugexp=les%3Beqn%2Ccconf%3D1.0%2Cmin_length%3D2%2Crate_low%3D0.025%2Crate_high%3D0.025%2Csecond_pass%3Dfalse%2Cnum_suggestions%3D2%2Cignore_bad_origquery%3Dtrue&gs_nf=1&gs_mss=AGING%20RESI&tok=ga9zOrM8UQ_ymJWHXg8iCA&pq=Search%20for%20topics&cp=12&gs_id=23&xhr=t&q=AGING%20RESINS&pf=p&sclient=psy-ab&oq=AGING+RESINS&gs_l=&pbx=1&bav=on.2,or.r_gc.r_pw.r_qf.&fp=46e1bb21f73534ca&biw=1152&bih=635

[Frank Krygowski]

I was talking about _suddenly_ breaking. And whether or not it's
deserved, carbon fiber parts have a reputation for breaking suddenly -
or at least, with much less warning than metal.

I've never broken a handlebar, but I've replaced two sets (both
aluminum) when I got worried about their extended life. But that friend
of mine I mentioned got no warning at all with his aluminum bars. He
said the break occurred when a light turned green and he began
accelerating hard across the intersection, pulling up on the bars.
Instead of making it across the road, he took a ride in an ambulance.

FWIW, he ran a bike shop, and he hung the bars above the counter as a
"don't let this happen to you" display.

--
- Frank Krygowski

[DirtRoadie]

On Aug 17, 7:56 pm, Frank Krygowski <frkrygowREM...@gEEmail.com>
wrote:
> Joe Riel wrote:
> > DirtRoadie<DirtRoa...@aol.com>  writes:

>
> >>>>>> Agreed. I had half the bars break off next to the clamp near the end of
> >>>>>> a longish road race. 10 km to go and I finished with the break, even
> >>>>>> chased down an escapee coming in to town. I didn't crash.
>
> >>>>> So you rode 10 km with half the handlebar broken off?  Did you lash the
> >>>>> broken-off half to your top tube, toss it jauntily over your shoulder,
> >>>>> or just carry it loosely in your hand as you chased down that other
> >>>>> rider?  I really am curious about details, James.
>
> >>>> It's do-able.http://www.youtube.com/watch?v=9-Pu71HXrfY
>
> >>> Oh.  I missed the part where James said he whipped out the tape and
> >>> taped the bar down while he rode in the race.  My fault.
>
> >> Yes please try to pay attention. The guy that I described in a
> >> criterium rode  in essentially the same manner as shown the video,
> >> sans tape, just holding bars together on one side with a hand.
> >> So do you or don't you retract your silly "zero chance of catching
> >> yourself" comment?
>
> > Ah, but did the bar break suddenly?  What is the typical failure mode?
> > I've broken handlebars near the stem and had to ride home with half a
> > bar.  The initial fracture was on the lower half, the separation occurred
> > when pulling up on the bars from a stop.  Didn't crash.
>
> I was talking about _suddenly_ breaking.

You mean like hitting a bump and having the bar snap?
That's what I witnessed and was describing.
That is well within what I understand "sudden" to mean.
On planet Krygowski things may be different

> And whether or not it's
> deserved, carbon fiber parts have a reputation for breaking suddenly -
> or at least, with much less warning than metal.

Nice back pedaling! Is "sudden" different for carbon fiber than it is
for aluminum?

> I've never broken a handlebar, but I've replaced two sets (both
> aluminum) when I got worried about their extended life.

And this is relevant because.....?

> But that friend
> of mine I mentioned got no warning at all with his aluminum bars.

And this single incident now qualifies you to make broad
pronouncements about " zero chance of 'catching'
yourself _if it fails suddenly_?"

>  He
> said the break occurred when a light turned green and he began
> accelerating hard across the intersection, pulling up on the bars.
> Instead of making it across the road, he took a ride in an ambulance.

Yes, so?

> FWIW, he ran a bike shop, and he hung the bars above the counter as a
> "don't let this happen to you" display.
>
> --
> - Frank Krygowski

Well that certainly proves conclusively that "zero chance of
'catching'
yourself if it fails suddenly." On one planet.
Frank why is it so bothersome to you that others have had experiences
different from your incompetent friends?
DR

[DirtRoadie]

Those are also structures that carry cantilevered loads. In contrast
to frames and rims.
See also
http://polytube-cycles.de/en/services.html
"Note:
The repair of damaged rims, forks, stems and other components is
currently not possible"

DR

[John B.]

He may not have the capability to repair forks, or stems; or more
likely he may not want to fool with small stuff that he can't make a
decent profit on, but I can tell you that building or repairing
composite items that carry a "cantilevered loads" is certainly
possible - I've done it myself and repairing composite is about as
easy a repair as you can find. Far easier then repairing a wooden
cantilevered beam, in fact.

They have been building, and repairing fiberglass items for 70 years
or more. I think that the first glass fiber reinforced boat dates back
to 193-something. It is hardly an esoteric art.
Cheers,
John B.

[John B.]

My experience has been somewhat different. A guy wants to build a
diesel tank, for example. He starts out by saying "what can I build a
tank out of that diesel won't bother". And he selects reinforced epoxy
because (1) diesel doesn't bother it, (2) it is reasonably priced and
(3) it is easy to work with.

But I've always looked at the carbon bicycle business with a certain
amount of awe. Here is a bunch of guys building bicycle frames out of
a material that has been used for golf club shafts ( a very similar
practice to building tubes for bicycle frames) since 1973 - nearly 40
years ago, and talking as though they have just invented gravity.

(And a bunch of guys on the other side of the counter paying premium
for 40 year old technology :-)

>>
>> Having said that, the beautiful, shiny finish on some carbon
>> components isn't a structural part of the component, it is a "clear
>> coat" and likely is not epoxy resin, although it might be an epoxy
>> based paint. But on the other hand it might not be and as there is no
>> way of knowing what a particular manufacturer uses as clear coat I
>> can't comment on its resistance to mineral oils.
>
>I think its a specification which should be checked with the supplier
>or manufacturer or use only non-petroleum oils and solvents.

Cheers,
John B.

[Lou Holtman]

Op 18-8-2012 13:10, John B. schreef:

Are you comparing a boat to a fork/stem safety wise or stress wise? When
a fork breaks suddenly there is a great chance you end up at the dentist
for a major repair. A decent fork costs 200-300 euro from a respected
manufacturer. That is a lot cheaper than the dentist bill.
People are so ignorant. Buddy of mine crashed and the handlebar was 30
degrees out of wack. In a rush he wanted to straighten without loosen
the bolts of his stem. Geezzzz.... When I told him to check the CF
steerer at home he asked "Why?"

Lou, don't try to repair forks, stems, seatposts. Even discussing it...

[thirty-six]

At least Columbus has offered a professional line of forks which use a
titanium mesh, I assume to rovide a compressive energy to the fork's
surface to prevent fragmentation and splintering. Raises the price
from around £110 to £160 Should I buid up a new fast-tour frameset,
it will likely be with this type of fork if titanium forks are not
available.

[Frank Krygowski]

<yawn> Stalkers are boring.

- Frank Krygowski

--
- Frank Krygowski

[Frank Krygowski]

John B. wrote:
> ...

> But I've always looked at the carbon bicycle business with a certain
> amount of awe. Here is a bunch of guys building bicycle frames out of
> a material that has been used for golf club shafts ( a very similar
> practice to building tubes for bicycle frames) since 1973 - nearly 40
> years ago, and talking as though they have just invented gravity.
>
> (And a bunch of guys on the other side of the counter paying premium
> for 40 year old technology :-)

Of course, there are significant differences between (say) a bike fork
and a golf club shaft - or a fly rod, or a violin bow, or many other
objects available in carbon fiber. I think the loads seen by bike
components are much more variable (both from rider to rider, and from
time to time under a given rider) and thus, less well understood.

And at the same time designers try to resist relatively unknown loads,
they try to minimize weight. Building a carbon fork or frame that
matched the weight of an aluminum or steel one would be much less of a
trick. Trying to shave every gram makes the job much more difficult.

Oh, and while shaving every gram and fighting poorly understood loads,
the designer has to preserve the well being of the guy riding the frame.
If a carbon fiber violin bow breaks, the violinist grabs his spare and
continues. If a golf club shaft fails, the golfer secretly rejoices at
the chance to tell his buddies "That's probably been bad for the last
ten rounds; it's why you beat me." But when a fork or handlebar fails,
the bicyclist wakes up and tries to find his teeth.

--
- Frank Krygowski

[Dan]

I think the problem here was the hole, wasn't it?

[Dan O]

On Aug 18, 1:14 pm, Frank Krygowski <frkrygowREM...@gEEmail.com>
wrote:

I think the problem here was the hole in the bar, wasn't it?

[John B.]

On Sat, 18 Aug 2012 16:14:00 -0400, Frank Krygowski
<frkrygo...@gEEmail.com> wrote:

>John B. wrote:
>> ...
>> But I've always looked at the carbon bicycle business with a certain
>> amount of awe. Here is a bunch of guys building bicycle frames out of
>> a material that has been used for golf club shafts ( a very similar
>> practice to building tubes for bicycle frames) since 1973 - nearly 40
>> years ago, and talking as though they have just invented gravity.
>>
>> (And a bunch of guys on the other side of the counter paying premium
>> for 40 year old technology :-)
>
>Of course, there are significant differences between (say) a bike fork
>and a golf club shaft - or a fly rod, or a violin bow, or many other
>objects available in carbon fiber. I think the loads seen by bike
>components are much more variable (both from rider to rider, and from
>time to time under a given rider) and thus, less well understood.
>

I'm not so sure.

Columbus, certainly, constructed a device to measure and record strain
at various points on the frame, in real time, and brags that it
allowed them to design tubes with not only varying shapes and size but
thickness and butt dimensions.

At the same time the power output of the motor is far better
understood. I'll bet that every top rider in the world has, by now
been tested for power output both instantaneous and sustained.

Wind resistance? Been tested and re-tested. Even the material in Lance
Armstrong's shirt was designed with the data from wind tunnel testing.

There isn't much left, is there. A 110 lb rider with a power output of
3 HP on a 15 lb. vehicle with the following dimensions and a vertical
and horizontal CG of X and Y, mounted on wheels and tires with a
compliance of Z traveling at a velocity of V on a slope of a specified
angle with known air density and a measured drag, in a district with a
known gravitational attraction approaching a curve of known angle,
radius and length.

Certainly it can be calculated.

>And at the same time designers try to resist relatively unknown loads,
>they try to minimize weight. Building a carbon fork or frame that
>matched the weight of an aluminum or steel one would be much less of a
>trick. Trying to shave every gram makes the job much more difficult.
>

Unknown loads? Not hardly. I've been out of school for over 50 years
now and I'll bet I can still do (if I still find my references books)
a proper stress analysis.

But you are accurate in the last sentence. Shaving weight. Weight, or
lack thereof, sells so bicycle designers appear to design with their
first design criteria being "lighter then the competitor" and things
break. But give a bit of thought to the problem. Somebody, a day or so
ago said that he had broken a number of cranks. But at the same time
there are thousands of "hot Rods" running aluminum connecting rods
that don't break. (granted the load cycle on a connecting rod is
slightly different that a bicycle crank arm, but similar enough to
make my point).

>Oh, and while shaving every gram and fighting poorly understood loads,
>the designer has to preserve the well being of the guy riding the frame.
> If a carbon fiber violin bow breaks, the violinist grabs his spare and
>continues. If a golf club shaft fails, the golfer secretly rejoices at
>the chance to tell his buddies "That's probably been bad for the last
>ten rounds; it's why you beat me." But when a fork or handlebar fails,
>the bicyclist wakes up and tries to find his teeth.

Not hardly, If a golf club shaft breaks the player might well lose the
Nationals. Golf magazines would immediately publish the news that Joe
missed a birdy on the 17th because his driver shaft broke and his
drive as only 50 yards and immediately the sale of the Super Wonderful
Golf Club Company drops to zero. While it may not worry about the
players teeth it certainly has a vital interest in things not
breaking.

Your argument that bicycle design is some arcane black art dealing
with unknown forces and loads is hog wash, or if actually true an
indication that totally ignorant people are building bicycles, which
I'm inclined to discount.

Back in the mid 1960's I was peripherally involved in a project to
measure the load on an F-4 tail hook when it grabbed the arresting
gear. At that time the strain gage was a piece of plastic abut 1/4"
wide and 3/4" long, bonded to the hook shank. Certainly measuring
technology has gotten more sophisticated in the past 50 years.

A modern racing bicycle is essentially two triangles and calculating
the strain on a triangle is a very, very, old technique.

Strength of materials? Testing methods and techniques certainly are as
old as the metal working art. Every stressed part for an airplane I
was involved with specified, in addition to size and shape, the
material and strength.

So what is left Frank?

Cheers,
John B.

[John B.]

On Sat, 18 Aug 2012 13:21:47 -0700 (PDT), Dan O <danov...@gmail.com>
wrote:

In the handle bar?

The basic problem is space. The general rule in epoxy work is that a
12 to 1 overlap is as strong as the parent material so to repair a
broken tune would involve grinding a taper of 12::1 on each half of
the joint and then overlaying this with layers of carbon cloth and
epoxy. However to have the same strength as the wall thickness the
ratio of carbon to epoxy must be the same and the handlebar was
probably made either by vacuum bagging or more likely in a mold with
an inflatable core - the saturated carbon cloth is wrapped around an
inflatable tube and placed in a female mold. the mold is closed and
pressure is applied to the tube and excess resin is squeezed out of
the composite.

So, to repair a handlebar you will need to grind a taper on some 24
inches of tube. Then, since you may not be able to compress the
carbon/epoxy to the same density you will probably simply make the
wall thickness greater, either internally or externally.

Added thickness means added weight which the customer may notice, and
bitch about. 24 inches of tube to taper? On a 42 cm.(18 inch) handle
bar? End up with an unsatisfied customer because the handlebar is
heavier then the original?

Better just tell them it "can't be done with current technology".


Cheers,
John B.

[John B.]

And when a boat breaks you drown. Which is better? A trip to the
dentist or dying?

And, I might add, the boat building came long before the composite
bikes. The bikes are built with technology developed by the boat
builders.

>People are so ignorant. Buddy of mine crashed and the handlebar was 30
>degrees out of wack. In a rush he wanted to straighten without loosen
>the bolts of his stem. Geezzzz.... When I told him to check the CF
>steerer at home he asked "Why?"
>
>Lou, don't try to repair forks, stems, seatposts. Even discussing it...

Cheers,
John B.

[frkr...@gmail.com]

On Saturday, August 18, 2012 9:49:55 PM UTC-4, John B. wrote:
> On Sat, 18 Aug 2012 16:14:00 -0400, Frank Krygowski
>
> <frkrygo...@gEEmail.com> wrote:
>
> >Of course, there are significant differences between (say) a bike fork
>
> >and a golf club shaft - or a fly rod, or a violin bow, or many other
>
> >objects available in carbon fiber. I think the loads seen by bike
>
> >components are much more variable (both from rider to rider, and from
>
> >time to time under a given rider) and thus, less well understood.
>
> >
>
> I'm not so sure.
>
>
>
> Columbus, certainly, constructed a device to measure and record strain
>
> at various points on the frame, in real time, and brags that it
>
> allowed them to design tubes with not only varying shapes and size but
>
> thickness and butt dimensions.
>
>
>
> At the same time the power output of the motor is far better
>
> understood. I'll bet that every top rider in the world has, by now
>
> been tested for power output both instantaneous and sustained.

I'm sure that there have been lots of riders tested for power output. But I don't think that's the source of the major loads on a bike frame. Rather, the major loads come from things like hitting potholes, jumping the bike (for those who do that), unplanned events like falls, and perhaps even mishandling the bike when it's not being ridden - like today, when my wife and I nearly dropped our tandem when we tried to load it onto the roof rack on our car. :-(

Furthermore, I think a lot of those loads are far worse for, um, larger amateur riders who ride with less skill. A 120 pound pro probably handles potholes with a lot more finesse than a 230 pound novice who just bought the "best" (i.e. most expensive) bike the bike shop had - so he could lose the weight he gained by working long hours to afford fancy toys.

> There isn't much left, is there. A 110 lb rider with a power output of
>
> 3 HP on a 15 lb. vehicle with the following dimensions and a vertical
>
> and horizontal CG of X and Y, mounted on wheels and tires with a
>
> compliance of Z traveling at a velocity of V on a slope of a specified
>
> angle with known air density and a measured drag, in a district with a
>
> known gravitational attraction approaching a curve of known angle,
>
> radius and length.
>
> Certainly it can be calculated.

I think it would be easier to calculate if the 3 HP came from a smooth running motor than from a human being. For example, one human might do that in a high gear at 60 rpm, rocking the bike mightily while yanking on the bars, while another might do it in a lower gear at 130 rpm with the bike running much straighter. Motors are more predictable.

>
>
>
> >And at the same time designers try to resist relatively unknown loads,
>
> >they try to minimize weight. Building a carbon fork or frame that
>
> >matched the weight of an aluminum or steel one would be much less of a
>
> >trick. Trying to shave every gram makes the job much more difficult.
>
> >
>
> Unknown loads? Not hardly. I've been out of school for over 50 years
>
> now and I'll bet I can still do (if I still find my references books)
>
> a proper stress analysis.

Yet there are people who take the trouble to do FEA analyses of bike frames, something that's not necessary for simple stress situations.

Even FEA doesn't necessarily give a suitable picture. With all FEA, the loads and restraints make a big difference in the results, and I'm not sure the common assumptions are really accurate. For example, it's common to assume the rear dropouts are fixed in both translation and rotation (as at http://engr.bd.psu.edu/davej/classes/fea1_hw5b.html). But if they're actually clamped to a somewhat flexible axle in a somewhat flexible wheel on a tire that moves laterally as the bike rolls, is a totally fixed dropout really accurate? I'm not so sure. Thus even FEA gives only an approximation.

> Back in the mid 1960's I was peripherally involved in a project to
>
> measure the load on an F-4 tail hook when it grabbed the arresting
>
> gear. At that time the strain gage was a piece of plastic abut 1/4"
>
> wide and 3/4" long, bonded to the hook shank. Certainly measuring
>
> technology has gotten more sophisticated in the past 50 years.

Well, strain gages are still the same, although they've long been available in much smaller sizes than that. They're a very mature technology.

Thing is, a tailhook is probably a relatively simple problem. It's probably what's called a "two force member." It supports only tensile loads, except for some brief rotational inertia effects. It's a problem suitable for a beginning class in stress analysis.

And BTW, assuming the tailhook is essentially a rod of uniform cross section, a large strain gage is perfectly appropriate, since the stress would be expected to be very uniform, i.e. no steep stress gradient. An area like the bottom bracket or head tube of a bike has stresses that vary tremendously over small distances. See http://www.designworldonline.com/mountain-bike-company-uses-fea-to-design-fast-bikes-faster/
So a 1/16" strain gage would be more appropriate, there, and even that only reports the average (not peak) stress over its length. Yet fatigue resistance depends on the peak stress, not any average stress.

> A modern racing bicycle is essentially two triangles and calculating
>
> the strain on a triangle is a very, very, old technique.

If it were a pinned truss, or something approximating a pinned truss, it would be easy. But it's not. If were so easy, nobody would even bother to do FEA.

- Frank Krygowski

[James]

The Al bar that broke while I was racing did not give minutes of
warning. During the race I had been pulling on them out of the seat up
some short but steep hills. When it actually broke was just as I
finished a turn on a long slight down hill at about 50 km/h. I moved to
the right to let the bunch through and while in the drops noticed the
bars felt odd for a moment, then the right side just dropped away. That
moment when the bars felt odd was enough for me to react and take weight
off the RHS. That moment lasted for all of a second - maybe 2.

> I've never broken a handlebar, but I've replaced two sets (both
> aluminum) when I got worried about their extended life. But that friend
> of mine I mentioned got no warning at all with his aluminum bars. He
> said the break occurred when a light turned green and he began
> accelerating hard across the intersection, pulling up on the bars.
> Instead of making it across the road, he took a ride in an ambulance.
>
> FWIW, he ran a bike shop, and he hung the bars above the counter as a
> "don't let this happen to you" display.
>

My mate who broke a CF bar recently had it snap as he was accelerating
across an intersection. He didn't fall, but when I questioned him on it
yesterday said he was lucky not to fall because there was plenty of cars
and he may well have been run over had he fallen.

The fact remains that a crash is not as inevitable as you made out,
though all agree a crash is quite possible and the bars should be
replaced before starting a ride.

--
JS.

[James]

On 18/08/12 21:34, Lou Holtman wrote:

> Are you comparing a boat to a fork/stem safety wise or stress wise? When
> a fork breaks suddenly there is a great chance you end up at the dentist
> for a major repair. A decent fork costs 200-300 euro from a respected
> manufacturer. That is a lot cheaper than the dentist bill.

$180

http://www.wiggle.co.uk/easton-ec70-carbon-road-forks/

Are they decent? I hope so. I put my smile in their hands ;-)

--
JS.

[James]

On 19/08/12 05:58, Frank Krygowski wrote:

> <yawn> Stalkers are boring.

Trolls are more so.

--
JS.

[James]

Can you find a standardised bump in the road?

Not saying there isn't one, but you left it out.

--
JS.

[thirty-six]

On Aug 19, 3:24 am, John B. <johnbsloc...@gmail.com> wrote:
> On Sat, 18 Aug 2012 13:34:41 +0200, Lou Holtman
>
>
>
>
>
>
>
>
>
> <lou.holt...@usenet.nl> wrote:
> >Op 18-8-2012 13:10, John B. schreef:
> >> On Fri, 17 Aug 2012 22:59:29 -0700 (PDT), DirtRoadie

i think you will find, if you care to look, that the current
technology in carbon bicycle frames evolved from the work on monocoque
sports cars, most notably Lotus, who IIRC were offering 3/4 monocoque
carbon-fibre chassis from around 1979

[thirty-six]

On Aug 19, 4:57 am, frkry...@gmail.com wrote:
> On Saturday, August 18, 2012 9:49:55 PM UTC-4, John B. wrote:
> > On Sat, 18 Aug 2012 16:14:00 -0400, Frank Krygowski
>

> > <frkrygowREM...@gEEmail.com> wrote:
>
> > >Of course, there are significant differences between (say) a bike fork
>
> > >and a golf club shaft - or a fly rod, or a violin bow, or many other
>
> > >objects available in carbon fiber.  I think the loads seen by bike
>
> > >components are much more variable (both from rider to rider, and from
>
> > >time to time under a given rider) and thus, less well understood.
>
> > I'm not so sure.
>
> > Columbus, certainly, constructed a device to measure and record strain
>
> > at various points on the frame, in real time, and brags that it
>
> > allowed them to design tubes with not only varying shapes and size but
>
> > thickness and butt dimensions.
>
> > At the same time the power output of the motor is far better
>
> > understood. I'll bet that every top rider in the world has, by now
>
> > been tested for power output both instantaneous and sustained.
>
> I'm sure that there have been lots of riders tested for power output.  But I don't think that's the source of the major loads on a bike frame.  Rather, the major loads come from things like hitting potholes, jumping the bike (for those who do that), unplanned events like falls, and perhaps even mishandling the bike when it's not being ridden - like today, when my wife and I nearly dropped our tandem when we tried to load it onto the roof rack on our car.  :-(
>
> Furthermore, I think a lot of those loads are far worse for, um, larger amateur riders who ride with less skill.  A 120 pound pro probably handles potholes with a lot more finesse than a 230 pound novice who just bought the "best" (i.e. most expensive) bike the bike shop had - so he could lose the weight he gained by working long hours to afford fancy toys.

Poor wheels will ruin both a terrifc or mediocre frameset. A really
good pair of wheels will usually transform a mediocre frame (with a
fork swap) to something outstanding, with the right pair of legs. The
difference between an average frame and a great frame is 1/10 the
difference (wet finger in the air test) between optimised wheels and
any old pair of sloppily built wheels.
Trouble is that many medium and small production frames are grossly
overbuilt due to the ecpectation that they are going to be ridden by
some fat-arsed wannabe with sloppy wheels.

>
> > There isn't much left, is there. A 110 lb rider with a power output of
>
> > 3 HP on a 15 lb. vehicle with the following dimensions and a vertical
>
> > and horizontal CG of X and Y, mounted on wheels and tires with a
>
> > compliance of Z traveling at a velocity of V on a slope of a specified
>
> > angle with known air density and a measured drag, in a district with a
>
> > known gravitational attraction approaching a curve of known angle,
>
> > radius and length.
>
> > Certainly it can be calculated.
>
> I think it would be easier to calculate if the 3 HP came from a smooth running  motor than from a human being.  For example, one human might do that in a high gear at 60 rpm, rocking the bike mightily while yanking on the bars, while another might do it in a lower gear at 130 rpm with the bike running much straighter.  Motors are more predictable.
>
>
>
>
>
>
>
>
>
>
>
> > >And at the same time designers try to resist relatively unknown loads,
>
> > >they try to minimize weight.  Building a carbon fork or frame that
>
> > >matched the weight of an aluminum or steel one would be much less of a
>
> > >trick.  Trying to shave every gram makes the job much more difficult.
>
> > Unknown loads? Not hardly.  I've been out of school for over 50 years
>
> > now and I'll bet I can still do (if I still find my references books)
>
> > a proper stress analysis.
>
> Yet there are people who take the trouble to do FEA analyses of bike frames, something that's not necessary for simple stress situations.
>

> Even FEA doesn't necessarily give a suitable picture.  With all FEA, the loads and restraints make a big difference in the results, and I'm not sure the common assumptions are really accurate. For example, it's common to assume the rear dropouts are fixed in both translation and rotation (as athttp://engr.bd.psu.edu/davej/classes/fea1_hw5b.html). But if they're actually clamped to a somewhat flexible axle in a somewhat flexible wheel on a tire that moves laterally as the bike rolls, is a totally fixed dropout really accurate?  I'm not so sure. Thus even FEA gives only an approximation.

>
> > Back in the mid 1960's I was peripherally involved in a project to
>
> > measure the load on an F-4 tail hook when it grabbed the arresting
>
> > gear. At that time the strain gage was a piece of plastic abut 1/4"
>
> > wide and 3/4" long, bonded to the hook shank. Certainly measuring
>
> > technology has gotten more sophisticated in the past 50 years.
>
> Well, strain gages are still the same, although they've long been available in much smaller sizes than that.  They're a very mature technology.
>
> Thing is, a tailhook is probably a relatively simple problem.  It's probably what's called a "two force member." It supports only tensile loads, except for some brief rotational inertia effects.  It's a problem suitable for a beginning class in stress analysis.
>

> And BTW, assuming the tailhook is essentially a rod of uniform cross section, a large strain gage is perfectly appropriate, since the stress would be expected to be very uniform, i.e. no steep stress gradient.  An area like the bottom bracket or head tube of a bike has stresses that vary tremendously over small distances.  Seehttp://www.designworldonline.com/mountain-bike-company-uses-fea-to-de...

[John B.]

So? What is the difference between a fiberglass hull and a sports car
body? Look at the shape of the very early Porche's :-) But more
seriously, making a reinforced plastic structure is basically just a
matter of saturating a fabric with activated resin. Fiber orientation,
SCRIMP and all the rest are simply modifications of the basic
technique.

[John B.]

On Mon, 20 Aug 2012 15:53:31 -0700 (PDT), thirty-six
<thirt...@live.co.uk> wrote:

>On Aug 19, 4:57�am, frkry...@gmail.com wrote:
>> On Saturday, August 18, 2012 9:49:55 PM UTC-4, John B. wrote:
>> > On Sat, 18 Aug 2012 16:14:00 -0400, Frank Krygowski
>>
>> > <frkrygowREM...@gEEmail.com> wrote:
>>
>> > >Of course, there are significant differences between (say) a bike fork
>>
>> > >and a golf club shaft - or a fly rod, or a violin bow, or many other
>>
>> > >objects available in carbon fiber. �I think the loads seen by bike
>>
>> > >components are much more variable (both from rider to rider, and from
>>
>> > >time to time under a given rider) and thus, less well understood.
>>
>> > I'm not so sure.
>>
>> > Columbus, certainly, constructed a device to measure and record strain
>>
>> > at various points on the frame, in real time, and brags that it
>>
>> > allowed them to design tubes with not only varying shapes and size but
>>
>> > thickness and butt dimensions.
>>
>> > At the same time the power output of the motor is far better
>>
>> > understood. I'll bet that every top rider in the world has, by now
>>
>> > been tested for power output both instantaneous and sustained.
>>
>> I'm sure that there have been lots of riders tested for power output. �But I don't think that's the source of the major loads on a bike frame. �Rather, the major loads come from things like hitting potholes, jumping the bike (for those who do that), unplanned events like falls, and perhaps even mishandling the bike when it's not being ridden - like today, when my wife and I nearly dropped our tandem when we tried to load it onto the roof rack on our car. �:-(
>>

And of course only bicycles have hit a pot hole so calculating the
stress, is a totally new science?

>> Furthermore, I think a lot of those loads are far worse for, um, larger amateur riders who ride with less skill. �A 120 pound pro probably handles potholes with a lot more finesse than a 230 pound novice who just bought the "best" (i.e. most expensive) bike the bike shop had - so he could lose the weight he gained by working long hours to afford fancy toys.
>

What difference does it make? A body of X weight hitting a pot hole is
a doable calculation.

>Poor wheels will ruin both a terrifc or mediocre frameset. A really
>good pair of wheels will usually transform a mediocre frame (with a
>fork swap) to something outstanding, with the right pair of legs. The
>difference between an average frame and a great frame is 1/10 the
>difference (wet finger in the air test) between optimised wheels and
>any old pair of sloppily built wheels.
>Trouble is that many medium and small production frames are grossly
>overbuilt due to the ecpectation that they are going to be ridden by
>some fat-arsed wannabe with sloppy wheels.
>>
>> > There isn't much left, is there. A 110 lb rider with a power output of
>>
>> > 3 HP on a 15 lb. vehicle with the following dimensions and a vertical
>>
>> > and horizontal CG of X and Y, mounted on wheels and tires with a
>>
>> > compliance of Z traveling at a velocity of V on a slope of a specified
>>
>> > angle with known air density and a measured drag, in a district with a
>>
>> > known gravitational attraction approaching a curve of known angle,
>>
>> > radius and length.
>>
>> > Certainly it can be calculated.
>>
>> I think it would be easier to calculate if the 3 HP came from a smooth running �motor than from a human being. �For example, one human might do that in a high gear at 60 rpm, rocking the bike mightily while yanking on the bars, while another might do it in a lower gear at 130 rpm with the bike running much straighter. �Motors are more predictable.
>>

I wonder why? After all an internal combustion, or a steam, engine for
that matter, does not have a constant connecting rod loading and
engineers have been calculating those loads for a while now. And
(gulp) even doing it at different RPM's in difference directions
calculating both the loading in both tension and compression.

>> > >And at the same time designers try to resist relatively unknown loads,
>>
>> > >they try to minimize weight. �Building a carbon fork or frame that
>>
>> > >matched the weight of an aluminum or steel one would be much less of a
>>
>> > >trick. �Trying to shave every gram makes the job much more difficult.
>>
>> > Unknown loads? Not hardly. �I've been out of school for over 50 years
>>
>> > now and I'll bet I can still do (if I still find my references books)
>>
>> > a proper stress analysis.
>>
>> Yet there are people who take the trouble to do FEA analyses of bike frames, something that's not necessary for simple stress situations.
>>
>> Even FEA doesn't necessarily give a suitable picture. �With all FEA, the loads and restraints make a big difference in the results, and I'm not sure the common assumptions are really accurate. For example, it's common to assume the rear dropouts are fixed in both translation and rotation (as athttp://engr.bd.psu.edu/davej/classes/fea1_hw5b.html). But if they're actually clamped to a somewhat flexible axle in a somewhat flexible wheel on a tire that moves laterally as the bike rolls, is a totally fixed dropout really accurate? �I'm not so sure. Thus even FEA gives only an approximation.
>>
>> > Back in the mid 1960's I was peripherally involved in a project to
>>
>> > measure the load on an F-4 tail hook when it grabbed the arresting
>>
>> > gear. At that time the strain gage was a piece of plastic abut 1/4"
>>
>> > wide and 3/4" long, bonded to the hook shank. Certainly measuring
>>
>> > technology has gotten more sophisticated in the past 50 years.
>>
>> Well, strain gages are still the same, although they've long been available in much smaller sizes than that. �They're a very mature technology.
>>
>> Thing is, a tailhook is probably a relatively simple problem. �It's probably what's called a "two force member." It supports only tensile loads, except for some brief rotational inertia effects. �It's a problem suitable for a beginning class in stress analysis.
>>
>> And BTW, assuming the tailhook is essentially a rod of uniform cross section, a large strain gage is perfectly appropriate, since the stress would be expected to be very uniform, i.e. no steep stress gradient. �An area like the bottom bracket or head tube of a bike has stresses that vary tremendously over small distances. �Seehttp://www.designworldonline.com/mountain-bike-company-uses-fea-to-de...
>> So a 1/16" strain gage would be more appropriate, there, and even that only reports the average (not peak) stress over its length. �Yet fatigue resistance depends on the peak stress, not any average stress.
>>

Frank, I've already told you that Columbus says that they have
instrumented a bicycle frame and used the data to design new frame
tubes with varying thickness and cross section to better resist the
loads. You are getting all concerned about something that is already
accomplished.

As for the tail hook it is not a constant width or cross section so it
is not a single average load. In addition there are several loads
imposed on the hook, sometimes several at the same time.

As for instrumentation, you need a wider experience. Modern race cars
commonly monitor things like the load on a front wheel and the
deflection of the suspension system, in real time, at 250 Km./Hr. The
technology is there, whether a bicycle designer uses it is really just
a decision to do it or not. The hardware is off the shelf.

>> > A modern racing bicycle is essentially two triangles and calculating
>>
>> > the strain on a triangle is a very, very, old technique.
>>
>> If it were a pinned truss, or something approximating a pinned truss, it would be easy. �But it's not. �If were so easy, nobody would even bother to do FEA.
>>

Nobody said it was simple, or difficult, I only said that it was
doable. If you believe it is too difficult to accomplish then don't
even start.


>> - Frank Krygowski

[Frank Krygowski]

John B. wrote:
> On Mon, 20 Aug 2012 15:53:31 -0700 (PDT), thirty-six
> <thirt...@live.co.uk> wrote:
>
>> On Aug 19, 4:57 am, frkry...@gmail.com wrote:
>>> On Saturday, August 18, 2012 9:49:55 PM UTC-4, John B. wrote:
>>>> A 110 lb rider with a power output of
>>>
>>>> 3 HP on a 15 lb. vehicle with the following dimensions and a vertical
>>>
>>>> and horizontal CG of X and Y, mounted on wheels and tires with a
>>>
>>>> compliance of Z traveling at a velocity of V on a slope of a specified
>>>
>>>> angle with known air density and a measured drag, in a district with a
>>>
>>>> known gravitational attraction approaching a curve of known angle,
>>>
>>>> radius and length.
>>>
>>>> Certainly it can be calculated.
>>>
>>> I think it would be easier to calculate if the 3 HP came from a smooth running motor than from a human being. For example, one human might do that in a high gear at 60 rpm, rocking the bike mightily while yanking on the bars, while another might do it in a lower gear at 130 rpm with the bike running much straighter. Motors are more predictable.
>>>
> I wonder why? After all an internal combustion, or a steam, engine for
> that matter, does not have a constant connecting rod loading and
> engineers have been calculating those loads for a while now. And
> (gulp) even doing it at different RPM's in difference directions

> calculating both the loading in both tension and compression....

>>>
> Frank, I've already told you that Columbus says that they have
> instrumented a bicycle frame and used the data to design new frame
> tubes with varying thickness and cross section to better resist the
> loads. You are getting all concerned about something that is already
> accomplished.

You don't seem to understand that Columbus's effort at instrumenting the
bike frame argues against your "this is simple" idea. Columbus would
not have taken the trouble to instrument the frame if the problem were
as simple as you imagine. Likewise, companies wouldn't bother to do FEA
analysis of their bike frames if the design process were easy.

Until perhaps 30 years ago, I think bike frame design was based on what
might be described as crowdsourced evolution. Designers would look at
the work of many other designers, as well as their own, to evaluate
their success. If frames often broke at a certain location, a designer
would beef up that location. If frames never broke at a certain
location, a designer would say "I can save some weight there" and make
the metal thinner. Only rarely would a real breakthrough occur - like,
for example, Gary Klein's large diameter aluminum tubes.

I doubt anyone since 1890 designed a bike frame using only simple stress
formulas and simplifying assumptions, the way (say) plant engineers
design (say) fixed mounting brackets. We won't accept the large safety
factors (or rather, the extra weight) that method requires.

> As for the tail hook it is not a constant width or cross section so it
> is not a single average load. In addition there are several loads
> imposed on the hook, sometimes several at the same time.

Give us a good drawing or clear close-up photo, and we can discuss in a
sub-thread. To me, it looks like a long, pretty simply shaped two force
member, with one major tensile load and perhaps some brief rotational
inertia loads. I think the loads and stresses are simpler to calculate
than those of a bike frame. And as I said, I think a 3/4" strain gage
would give perfectly adequate stress information on such a two-force
member. On a bike frame bottom bracket area with its extreme stress
gradient, that would be far too big to be useful.

--
- Frank Krygowski

[AMuzi]

I'm not an expert but these no longer look like WWII Corsair
tail hooks:

new:
http://images.devilfinder.com/go.php?q=F16+tail+hook

vintage:
http://masseyaero.org/projects/corsair/corsairbits/corsairbits-6.jpg

--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971

[Lou Holtman]

Op 20-8-2012 0:15, James schreef:

Al steerer, old technology.

Lou

[Kerry Montgomery]

"Frank Krygowski" <frkrygo...@gEEmail.com> wrote in message
news:k10e64$bm7$1...@dont-email.me...

Frank Krygowski,
There are other loads to be considered: impact when the hook hits the deck,
side loading if the plane isn't perpendicular to the wire when it hooks it,
and likely more.
Kerry

[James]

So what? I ride a bicycle with a steel frame, home built wheels and a
dynamo. What is decent? Is it chiefly reliability and longevity? How
much do you factor in weight? Is it something that hasn't had a large
number of failures in the field?

We all use fuzzy logic to determine what is decent in our own mind. Am
I to assume that in your mind old tech is not decent?

--
JS.

[Jay Beattie]

I hear a lot of different things about carbon steerers -- that modern
designs with thicker tube ends are stronger than aluminum, and that
aluminum presents the risk of disbonding. On the other hand, there
were a number of reported CF steerer failures a few years ago, and
they were perceived as dangerous by the clydesdale set (me). Aluminum
steerers are certainly more tolerant of stem clamp over-tightening. My
forks have an aluminum steerer, but then again, I'm always a few years
behind technology-wise. My brother is similar size and weight, and he
rides full carbon without incident -- so far. Apart from weight, it
kind of hard to tell whether old tech aluminum or new tech CF is
better. From a weight perspective, new tech is clearly better. From
a reliability perspective, old-old tech (steel) is probably the best
-- and retired steel forks can be used for home protection, seal
clubbing, grounding rods, boat anchors and so many other things.

-- Jay Beattie.

[frkr...@gmail.com]

There are always other things to be considered, no matter what the design.* But I maintain that design of a tailhook would be much more straightforward than design of a bike frame, at least if the bike frame was intended to be reasonably competitive regarding weight, stiffness, etc. I've posted links to FEA graphics showing the rather extreme stress gradients around the bottom bracket, head tube and seat cluster. The loads and stresses there are quite difficult to accurately represent and/or calculate. But even in the images Andrew linked, a tailhook sure looks like a two-force member.

* At a Design Education conference I attended long ago, a well-respected professor of mechanical design said he often started his students off by having them design a simple metal shelf that would be bolted to a concrete block wall at a factory work station. It was to protrude about 6" and be about 12" wide, and would hold the worker's adjustable wrench in easy reach, about 2 feet off the floor.

Easy, right? Except anyone who didn't design it to safely support 250 pounds lost serious credit. Because obviously, the worker's going to sit on that shelf the first day it's installed. There are always other things to be considered.

- Frank Krygowski

[John B.]

Frank, I will say one thing, you are adroit... at squirming about and
changing the subject to one that you might be able to justify.

I didn't say that calculating loads on bicycles was a "simple"
project. I did say that Columbus had done the collection of data and
used this data to design new frame tubes. I did not say that they had
calculated loads and forces on the frame as I assumed that you, being
a PE, would be able to figure out that in order to decide on the size,
shape and thickness of the newly designed tubes they would have had to
know the forces on the frame and therefore had performed the necessary
calculations as part of their design project.

>Until perhaps 30 years ago, I think bike frame design was based on what
>might be described as crowdsourced evolution. Designers would look at
>the work of many other designers, as well as their own, to evaluate
>their success. If frames often broke at a certain location, a designer
>would beef up that location. If frames never broke at a certain
>location, a designer would say "I can save some weight there" and make
>the metal thinner. Only rarely would a real breakthrough occur - like,
>for example, Gary Klein's large diameter aluminum tubes.
>

Well if you call large diameter aluminum tubes a "breakthrough" then
go ahead. I'd rather call it a bowing to the inevitable; that the
strength of aluminum is substantially less then steel.

>I doubt anyone since 1890 designed a bike frame using only simple stress
>formulas and simplifying assumptions, the way (say) plant engineers
>design (say) fixed mounting brackets. We won't accept the large safety
>factors (or rather, the extra weight) that method requires.
>

I've already said that Frank. I said that in my opinion bike designers
were designing the standard of "Lighter then the other guy's", with a
bit of "Cheap to manufacturer" thrown in as a "fudge factor".

>> As for the tail hook it is not a constant width or cross section so it
>> is not a single average load. In addition there are several loads
>> imposed on the hook, sometimes several at the same time.
>
>Give us a good drawing or clear close-up photo, and we can discuss in a
>sub-thread. To me, it looks like a long, pretty simply shaped two force
>member, with one major tensile load and perhaps some brief rotational
>inertia loads. I think the loads and stresses are simpler to calculate
>than those of a bike frame. And as I said, I think a 3/4" strain gage
>would give perfectly adequate stress information on such a two-force
>member. On a bike frame bottom bracket area with its extreme stress
>gradient, that would be far too big to be useful.

I'm really not interested in arguing the design of the tail hook. I
mentioned the project in partial evidence that instrumentation for
stress analysis is small and light and not a detriment (in case you
used that as an argument) to installing on a bike frame for data
collection.

[John B.]

On Tue, 21 Aug 2012 15:07:54 -0700, "Kerry Montgomery"
<kamo...@teleport.com> wrote:

>
>"Frank Krygowski" <frkrygo...@gEEmail.com> wrote in message
>news:k10e64$bm7$1...@dont-email.me...

>> Give us a good drawing or clear close-up photo, and we can discuss in a
>> sub-thread. To me, it looks like a long, pretty simply shaped two force
>> member, with one major tensile load and perhaps some brief rotational
>> inertia loads. I think the loads and stresses are simpler to calculate
>> than those of a bike frame. And as I said, I think a 3/4" strain gage
>> would give perfectly adequate stress information on such a two-force
>> member. On a bike frame bottom bracket area with its extreme stress
>> gradient, that would be far too big to be useful.
>>
>> --
>> - Frank Krygowski
>
>Frank Krygowski,
>There are other loads to be considered: impact when the hook hits the deck,
>side loading if the plane isn't perpendicular to the wire when it hooks it,
>and likely more.
>Kerry
>

Probably the major loads of interest is the speed and gross weight of
the plane when it hits the wire.

It might be of interest to know that any air force base that hosts
fighters has a arresting cable system installed which originally was
two lengths of ship's anchor chain laid down the sides of the runway
with a cable stretched across the runway connecting the two chains
together. (Very low maintenance device).

[Tom $herman (-_-)]

On 8/21/2012 7:57 PM, Jay Beattie wrote:
> I hear a lot of different things about carbon steerers -- that modern
> designs with thicker tube ends are stronger than aluminum, and that
> aluminum presents the risk of disbonding. On the other hand, there

> were a number of reported CF steerer failures a few years ago,[...]

Please, "carbon fiber reinforced polymer" or "CFRP". This is "tech", ya
know.

--
Tºm Shermªn - 42.435731°N, 83.985007°W
Post Free or Die!

[Tom $herman (-_-)]

On 8/21/2012 10:47 PM, John B. wrote:
> Well if you call large diameter aluminum tubes a "breakthrough" then
> go ahead. I'd rather call it a bowing to the inevitable; that the
> strength of aluminum is substantially less then steel.

However, the strength to weight (and stiffness to weight) of cro-moly
steel, 6000 and 7000 series aluminium alloys, and titanium/titanium
alloys are in the same ballpark.

[Tom $herman (-_-)]

On 8/21/2012 11:51 AM, Frank Krygowski wrote:
> John B. wrote:

> [...]

>> As for the tail hook it is not a constant width or cross section so it
>> is not a single average load. In addition there are several loads
>> imposed on the hook, sometimes several at the same time.
>
> Give us a good drawing or clear close-up photo, and we can discuss in a
> sub-thread. To me, it looks like a long, pretty simply shaped two force
> member, with one major tensile load and perhaps some brief rotational
> inertia loads. I think the loads and stresses are simpler to calculate
> than those of a bike frame. And as I said, I think a 3/4" strain gage
> would give perfectly adequate stress information on such a two-force
> member. On a bike frame bottom bracket area with its extreme stress
> gradient, that would be far too big to be useful.
>

I thought Tailhook involved Navy and Marine officers getting drunk and
sexually harassing and assaulting women.

[John B.]

Frank, why are you rabbiting on about tail hooks for? The discussion
was originally the possibility of repairing carbon frames. Then
digressed to the possibilities of actually analyzing the stresses on a
bicycle frame and no you are off and running chasing tail hooks.

Enough already.

>* At a Design Education conference I attended long ago, a well-respected professor of mechanical design said he often started his students off by having them design a simple metal shelf that would be bolted to a concrete block wall at a factory work station. It was to protrude about 6" and be about 12" wide, and would hold the worker's adjustable wrench in easy reach, about 2 feet off the floor.
>
>Easy, right? Except anyone who didn't design it to safely support 250 pounds lost serious credit. Because obviously, the worker's going to sit on that shelf the first day it's installed. There are always other things to be considered.
>

And now it is shelves.... what next? The Mars Mission? Whether the
moon landing was a hoax?

>- Frank Krygowski

[John B.]

On Wed, 22 Aug 2012 00:58:12 -0500, "Tom $herman (-_-)"
<""twshermanREMOVE\"@THI$southslope.net"> wrote:

>On 8/21/2012 7:57 PM, Jay Beattie wrote:
>> I hear a lot of different things about carbon steerers -- that modern
>> designs with thicker tube ends are stronger than aluminum, and that
>> aluminum presents the risk of disbonding. On the other hand, there
>> were a number of reported CF steerer failures a few years ago,[...]
>
>Please, "carbon fiber reinforced polymer" or "CFRP". This is "tech", ya
>know.

Right. Down to the LBS and say, "I want a carbon fiber reinforced
polymer bike", and the guy says, "We don't have those but we do have
these svelte carbon bikes right over here :-)

[John B.]

On Wed, 22 Aug 2012 01:03:01 -0500, "Tom $herman (-_-)"
<""twshermanREMOVE\"@THI$southslope.net"> wrote:

>On 8/21/2012 10:47 PM, John B. wrote:
>> Well if you call large diameter aluminum tubes a "breakthrough" then
>> go ahead. I'd rather call it a bowing to the inevitable; that the
>> strength of aluminum is substantially less then steel.
>
>However, the strength to weight (and stiffness to weight) of cro-moly
>steel, 6000 and 7000 series aluminium alloys, and titanium/titanium
>alloys are in the same ballpark.

So you use large diameter, but thinner, aluminum and viola! You are
lighter and stiffer then steel. Rocket Science it is not.

Apparently been going on for years. I recently read a review of the
Roman soldier's equipment and apparently they changed the helmet from
bronze to steel - lighter and stiffer, i.e., didn't dent so badly :-)

[Tom $herman (-_-)]

On 8/22/2012 6:48 AM, John B. wrote:
> So you use large diameter, but thinner, aluminum and viola!

I believe a viola is a fretless bowed musical instrument.

Voilà!

[Tom $herman (-_-)]

On 8/22/2012 6:48 AM, John B. wrote:

And if you go to Sprawl-Mart, you may be able to find a bicycle shaped
object with a plain carbon steel frame.

I also like to confound clueless LBS clerks by asking for tires/tubes by
ISO size.

[Jay Beattie]

On Aug 22, 5:45 am, "Tom $herman (-_-)" <""twshermanREMOVE\"@THI

I go to the gas station and demand 15 liters just to confound the
clueless attendants and to prove my superior knowledge of metric
volumes. Of course, this results in considerable confusion and
usually conflict with the attendant -- but I make my point!

-- Jay Beattie.

[thirty-six]

On Aug 22, 12:48 pm, John B. <johnbsloc...@gmail.com> wrote:

> On Tue, 21 Aug 2012 19:51:11 -0700 (PDT), frkry...@gmail.com wrote:

> Frank, why are you rabbiting on about tail hooks for? The discussion
> was originally the possibility of repairing carbon frames. Then
> digressed to the possibilities of actually analyzing the stresses on a
> bicycle frame and no you are off and running chasing tail hooks.
>
> Enough already.
>
> >* At a Design Education conference I attended long ago, a well-respected professor of mechanical design said he often started his students off by having them design a simple metal shelf that would be bolted to a concrete block wall at a factory work station.  It was to protrude about 6" and be about 12" wide, and would hold the worker's adjustable wrench in easy reach, about 2 feet off the floor.
>
> >Easy, right?  Except anyone who didn't design it to safely support 250 pounds lost serious credit.  Because obviously, the worker's going to sit on that shelf the first day it's installed.  There are always other things to be considered.
>
> And now it is shelves.... what next?  The Mars Mission? Whether the
> moon landing was a hoax?

I propose taktykill pen design.

[thirty-six]

On Aug 22, 12:48 pm, John B. <johnbsloc...@gmail.com> wrote:

did they use auto-hammers or did they have a roller-press?

[SMS]

On 8/16/2012 7:36 PM, jspa...@linuxquestions.net wrote:
> How safe is it to ride with a cracked carbon fibre road handlebar?
>
> This evening I went for a ride and ran over a small bump in the road while I was up out of the saddle with some of my weight on the tops of my bars. I heard a cracking sound and felt a splinter in my finger.
>
> I stopped to take a look and discovered that I had a small crack on the right underside of my FSA K-Wing handlebar. It's not around the stem. It appears to be around the opening where the brake cables go into.
>
> The bar itself is around 6 years old. The bump I ran over wasn't that harsh, so maybe it was a combination of my weight on it and age/fatigue of the bar.
>
> Anyways, is the handlebar still safe to ride on? It doesn't flex when I put weight on it, but I don't want it to snap off completely while I'm out riding and putting stress on it.

Avoid CF in high stress parts like forks, handlebars, and seat posts, at
all costs.

[Frank Krygowski]

John B. wrote:
>
> Frank, why are you rabbiting on about tail hooks for? The discussion
> was originally the possibility of repairing carbon frames. Then
> digressed to the possibilities of actually analyzing the stresses on a
> bicycle frame and no you are off and running chasing tail hooks.

John, you were the one who brought up tailhooks.


--
- Frank Krygowski

[Lou Holtman]

Op 22-8-2012 0:17, James schreef:

> On 22/08/12 04:07, Lou Holtman wrote:
>> Op 20-8-2012 0:15, James schreef:
>>> On 18/08/12 21:34, Lou Holtman wrote:
>>>
>>>> Are you comparing a boat to a fork/stem safety wise or stress wise?
>>>> When
>>>> a fork breaks suddenly there is a great chance you end up at the
>>>> dentist
>>>> for a major repair. A decent fork costs 200-300 euro from a respected
>>>> manufacturer. That is a lot cheaper than the dentist bill.
>>>
>>> $180
>>>
>>> http://www.wiggle.co.uk/easton-ec70-carbon-road-forks/
>>>
>>> Are they decent? I hope so. I put my smile in their hands ;-)
>>>
>>
>>
>> Al steerer, old technology.
>>
>
> So what?

I'm not to fond off a Al steerer glued to CF fork blades. I prefer a one
piece CF structure.

> I ride a bicycle with a steel frame, home built wheels and a
> dynamo. What is decent?

That is OK with me. Not decent is buying a (used) no name Chinese fork
on Ebay.

> Is it chiefly reliability and longevity?

That depends. When I bought my 895 gr CF frame I expected a lifespan of
5 years in normal use and accepted that after a severe crash I would
have to trash it. This frame lasts 7 years now so I'm in the plus and
this bike gave and still give me a lot of pleasant hours of riding. On
the other hand I would be very disapointed if my Ti frame would break
after 10 years. It reaches that age at the end of this season and all is
good so far.

> How
> much do you factor in weight?

Don't make it heavier than necessary. For a high end CF roadbike fork
today 450 gr is too heavy.

> Is it something that hasn't had a large
> number of failures in the field?

That is the number one criteria.

> We all use fuzzy logic to determine what is decent in our own mind. Am
> I to assume that in your mind old tech is not decent?

No I didn't said or meant that, but if you mean that heavy steel is
necessary to get a reliable and dependable frame I disagree.

Lou

[AMuzi]

My Kestrel fixie will start its 20th winter in a couple of
months. It's had two significant crashes and a host of
insults yet it has no rust (!) and rides just fine.

You can find both excellent and dismal in all materials.

[James]

On 23/08/12 03:51, Lou Holtman wrote:
> Op 22-8-2012 0:17, James schreef:
>> On 22/08/12 04:07, Lou Holtman wrote:
>>> Op 20-8-2012 0:15, James schreef:
>>>> On 18/08/12 21:34, Lou Holtman wrote:
>>>>
>>>>> Are you comparing a boat to a fork/stem safety wise or stress wise?
>>>>> When
>>>>> a fork breaks suddenly there is a great chance you end up at the
>>>>> dentist
>>>>> for a major repair. A decent fork costs 200-300 euro from a respected
>>>>> manufacturer. That is a lot cheaper than the dentist bill.
>>>>
>>>> $180
>>>>
>>>> http://www.wiggle.co.uk/easton-ec70-carbon-road-forks/
>>>>
>>>> Are they decent? I hope so. I put my smile in their hands ;-)
>>>>
>>>
>>>
>>> Al steerer, old technology.
>>>
>>
>> So what?
>
> I'm not to fond off a Al steerer glued to CF fork blades. I prefer a one
> piece CF structure.

There is merit in that, however I'm not fond of clamping a CF tube at
the stem (or bars).

My previous bike that I retired after 10 years service had CF fork
blades glued to an Al steerer. For a long time there were cracks around
the joint. I could never perceive any movement at the joint. I suspect
the paint was less flexible than the glue.

> > I ride a bicycle with a steel frame, home built wheels and a
>> dynamo. What is decent?
>
> That is OK with me. Not decent is buying a (used) no name Chinese fork
> on Ebay.

I'm suspect of no name brands also. I prefer to have a named company to
bitch to should I need dental work as well.

>> Is it chiefly reliability and longevity?
>
> That depends. When I bought my 895 gr CF frame I expected a lifespan of
> 5 years in normal use and accepted that after a severe crash I would
> have to trash it. This frame lasts 7 years now so I'm in the plus and
> this bike gave and still give me a lot of pleasant hours of riding. On
> the other hand I would be very disapointed if my Ti frame would break
> after 10 years. It reaches that age at the end of this season and all is
> good so far.

To each his own. The steel frame I retired after 10 years service got
re-birthed and is now being used by a fellow who loves it to death. It
may well last him another 10 years or more - provided he takes care of it.

>> How
>> much do you factor in weight?
>
> Don't make it heavier than necessary. For a high end CF roadbike fork
> today 450 gr is too heavy.

Thank goodness my EC70 forks meet that requirement ;-)

>> Is it something that hasn't had a large
>> number of failures in the field?
>
> That is the number one criteria.

I use this too.

>> We all use fuzzy logic to determine what is decent in our own mind. Am
>> I to assume that in your mind old tech is not decent?
>
> No I didn't said or meant that, but if you mean that heavy steel is
> necessary to get a reliable and dependable frame I disagree.

Reliable and dependable are more subjective terms. A friend is very
happy to get a CF frame replacement/upgrade every 2-3 years when he
cracks the one he's riding. Sure, it's light and stiff, but in my
opinion not reliable or dependable, or decent for that matter. And for
a training bike, I think it's silly.

I'm sure light steel can make a reliable and dependable frame, as can
Ti, Al, CFRP, timber and bamboo. Some designers err too much on the
side of light weight than dependable and reliable for me.

--
JS.

[James]

Unfortunately the same is not true of thin walled Al tubes. They dent
comparatively easily.

--
JS.

[thirty-six]

there's a reason not to use pure aluminium.

[thirty-six]

On Aug 22, 11:00 pm, James <james.e.stew...@gmail.com> wrote:
> On 23/08/12 03:51, Lou Holtman wrote:
>
>
>
>
>
>
>
>
>
> > Op 22-8-2012 0:17, James schreef:
> >> On 22/08/12 04:07, Lou Holtman wrote:
> >>> Op 20-8-2012 0:15, James schreef:
> >>>> On 18/08/12 21:34, Lou Holtman wrote:
>
> >>>>> Are you comparing a boat to a fork/stem safety wise or stress wise?
> >>>>> When
> >>>>> a fork breaks suddenly there is a great chance you end up at the
> >>>>> dentist
> >>>>> for a major repair. A decent fork costs 200-300 euro from a respected
> >>>>> manufacturer. That is a lot cheaper than the dentist bill.
>
> >>>> $180
>
> >>>>http://www.wiggle.co.uk/easton-ec70-carbon-road-forks/
>
> >>>> Are they decent? I hope so. I put my smile in their hands ;-)
>
> >>> Al steerer, old technology.
>
> >> So what?
>
> > I'm not to fond off a Al steerer glued to CF fork blades. I prefer a one
> > piece CF structure.
>
> There is merit in that, however I'm not fond of clamping a CF tube at
> the stem (or bars).

Use a plastic shim or taper ream the clamp.

>
> My previous bike that I retired after 10 years service had CF fork
> blades glued to an Al steerer.  For a long time there were cracks around
> the joint.  I could never perceive any movement at the joint.  I suspect
> the paint was less flexible than the glue.

Eugh, that would unerve me.

Accepting a second replacement is acepting the risk of riding a dodgy
frame, I wouldn't do it.

>
> I'm sure light steel can make a reliable and dependable frame, as can

There was a time when lightweight road racing frames were also used
for Cyclo-cross, before the general adoption of the short-arm sidepull
caliper brake in road racing. Most sporting bikes at least well into
the 70s were fitted with centrpulls and lightweight touring frames
were still fitted with them well into the 80s and probably beyond. It
was probably about 1990 I heard of 753 frames specifically being
created for cyclo-cross and a couple of years later were lugless cross
frames with 753 stays and forks. Considering that it took 20 years
before custom C-cross frames were offered after the adoption of
sidepull brakes at the top of the sport, it seems that lighweight
steel frames have demonstrated sufficient adequacy of purpose and
dependability, without question.

> Ti, Al, CFRP, timber and bamboo.  Some designers err too much on the
> side of light weight than dependable and reliable for me.

When a steel frame is designed with the correct stiffness in mind, in
a balanced manner, and is then constructed to a high standard of
workmanship, it has an adequate strength and fatigue life. A well-
constructed frame should allow the rider to ride into his grave at 125.

[Frank Krygowski]

thirty-six wrote:
>
> When a steel frame is designed with the correct stiffness in mind, in
> a balanced manner, and is then constructed to a high standard of
> workmanship, it has an adequate strength and fatigue life. A well-
> constructed frame should allow the rider to ride into his grave at 125.

Hmm. I don't know if I'll hit 125, but I ride a 40-year-old Raleigh at
least three or four times a week. I've been doing that since I got it
in trade in 1976.

--
- Frank Krygowski

[John B.]

No I didn't, I brought up instrumentation and mentioned tail hooks as
an example of 40 - 50 year old technology. assuming that readers would
grasp the assumption that technology had advanced in the past half
century. Apparently you didn't.

I can only assume that either (1) you have a poor grasp of the English
language, or (2) you know nothing about data recording, or (3) you are
changing the subject in an effort to "win" the argument.

Regarding possibility 1 and 2, I will, in the future use the most
basic English terms I can think of and go into tedious detail so you
can follow the thread. For assumption 3 I can offer no assistance
other then the kill-file.

[John B.]

Don't they teach history in British schools. The Romans used slaves
:-)

[John B.]

On Thu, 23 Aug 2012 08:13:12 +1000, James <james.e...@gmail.com>
wrote:

That is true, in a sense, for most high end bicycle parts, isn't it.
someone recently mentioned he had broken several cranks. Designed to
be light in weight as apposed to having a significant safety margin
one supposes.

[John B.]

Of course. It is comparatively a very weak material.

[John B.]

An acquaintance recently told me a similar story. He, a native born
English speaker, has never made any attempt to learn to speak the
local language and recently, having bought a car, drove into a filling
stations, pulled up to the pump and loudly ordered FILL IT UP. The gas
station guy gabbled something, in the local language of course, and my
friend insisted in an even louder voice I SAID FILL FUCKING THE TANK!
The gas guy shrugged and filled the tank; the foreigner paid his bill
and drove merrily off, only to come to a sputtering halt about a
quarter of a mile down the road.

It seems he had pulled up to the diesel pump.

It probably pays use terms that the guy pumping the gas understands.

[Frank Krygowski]

John B. wrote:
> On Wed, 22 Aug 2012 13:40:23 -0400, Frank Krygowski
> <frkrygo...@gEEmail.com> wrote:
>
>> John B. wrote:
>>>
>>> Frank, why are you rabbiting on about tail hooks for? The discussion
>>> was originally the possibility of repairing carbon frames. Then
>>> digressed to the possibilities of actually analyzing the stresses on a
>>> bicycle frame and no you are off and running chasing tail hooks.
>>
>> John, you were the one who brought up tailhooks.
>

> No I didn't, I brought up instrumentation and mentioned tail hooks...

Q.E.D.

> ... as

> an example of 40 - 50 year old technology. assuming that readers would
> grasp the assumption that technology had advanced in the past half
> century. Apparently you didn't.

If you want to discuss the technology of experimental stress analysis
and how it's advanced in the past 40 years, I can do that (although I
might first ask how many strain gages you've installed and worked with).
Or would you prefer to talk about brittle coatings for strain
measurement, perhaps? Or photoelasticity?

Or should we just stick to the non-experimental computation-intensive
stuff, like FEA? I've done at least a little work with all the above.


--
- Frank Krygowski

[thirty-six]

On Aug 23, 2:08 am, Frank Krygowski <frkrygowREM...@gEEmail.com>
wrote:

pay more attention to the engine than you do this ng and there is a
fair chance you could still be riding 20 miles a day at 100 as long as
you ignore the bs bounded about nutrition by govt and medico.

Tip 1 Except for butter and cream, products made from cows milk are
probably injurous to you.

2. Grain is for birds and professional athletes only, it is also
probably injurous to you, sugar almost certainly.

3. peel potatoes and throw the core away.

4. Black tea is generally injurous as with coffee, lay off them
both. Meat and less so fish is also injurous, again take it easy.

5 Lemon brew is awesome after waking.

6 Licensed doctors are generally only drug pushers and know little
about attainment and retention of health.

7 Walnut oil and coconut oils are good, rapeseed, maize and olive oils
are bad as is any hydrgenated oil..

8 Study the lymphatic and endocrine systems and how they are disrupted
from a healthy state. With vitality in both, the whole body remains
healthy. Stop eating the so-called man-made "foods" and eat what god
gave you. If you wouldn't make it yourself, why pay a trader to kill
you?

9 eggs are great, you don't need to kill them by cooking.

10. Eat leaves.

11 Be your own physician, there's no-one knows more about yourself.

12. Filtered beer is definitely bad, (undecided about yeasty beer)

[thirty-six]

Yes they probably did, but "steel"? AIUI we were still using wrought
iron into 19th century. I did see some drawings that suggested an
acient civilisation used an auto-hammer, possibly Babylonian.