CHOOSING A FORK

[[email protected]]

Getting my first custom frame built [steel] and need to choose a fork.
This machine will be built first for comfort then for speed. I just
turned 58 and am 220lbs +/- so weight isn't really a factor. I am
concerned about the safety of carbon forks even though they are
ubiquitous. So I want a great and inspiring ride and value for money.

I am assuming that the shock absorbing characteristics of carbon forks
are based on equivalent tire sizes. Since carbon forks are not designed
to accommodate tires 28mm or larger [the kind I prefer] would a steel
fork with a 28 or 32mm tire be just as comfortable and shock absorbing
[not to mention cheaper] than a carbon fork with a 25mm tire?

For long distance riding how will a 28/32mm tire on a steel fork
compare with a 25mm [28?] tire on a carbon fork regarding handling
efficiency and comfort? Is the rotating weight of the larger tire a
factor? Just read something about the larger tires having less?!
rolling resistance than the smaller ones. What about aerodynamics. How
much of this matters at 15mph +/-
Thanks for your answers and sharing your experience knowledge and
common sense .

 

[[email protected]]

Stan Kurz writes:

> Getting my first custom frame built [steel] and need to choose a
> fork. This machine will be built first for comfort then for speed.
> I just turned 58 and am 220lbs +/- so weight isn't really a factor.
> I am concerned about the safety of carbon forks even though they are
> ubiquitous. So I want a great and inspiring ride and value for
> money.

In a road bicycle, the frame does not cushion the ride, the tires do,
if anything. Longer chainstays allow not sitting directly over the
rear wheel and that is significant. Therefore, on a non-suspension
frame, frame material and shape will result in insignificant
suspension in comparison to tire resilience. There are often long
discussions about sound suppression but don't let that make a choice
for you. As you notice, there are many road bicycles today that have
no curl at the fork end, being straight from the crown to dropout.
You may not find that aesthetically pleasing as do many riders. It is
a frame builder's statement and requires an asymmetric fork
crown... and has no benefits, except as a conversation piece.

> I am assuming that the shock absorbing characteristics of carbon
> forks are based on equivalent tire sizes. Since carbon forks are
> not designed to accommodate tires 28mm or larger [the kind I prefer]
> would a steel fork with a 28 or 32mm tire be just as comfortable and
> shock absorbing [not to mention cheaper] than a carbon fork with a
> 25mm tire?

Stick with a conventional steel fork with fork-end curl. Forget
carbon. If it were more elastic than steel then it would suffer from
shimmy as never before. Carbon differences are in the higher
frequencies and depend on the modulus of elasticity. Because carbon
fiber forks are not homogeneous having bonding resins that dampen
lateral (tuning fork) high frequencies while carbon fiber carries
mainly tension and compression, the forces of interest.

> For long distance riding how will a 28/32mm tire on a steel fork
> compare with a 25mm [28?] tire on a carbon fork regarding handling
> efficiency and comfort? Is the rotating weight of the larger tire a
> factor? Just read something about the larger tires having less?!
> rolling resistance than the smaller ones. What about aerodynamics.
> How much of this matters at 15mph +/- Thanks for your answers and
> sharing your experience knowledge and common sense .

You will get greater performance results from the length of socks you
wear than from the effects you mention, some of which are as good as
not there. Get a frame that fits and use reliable components.

Jobst Brandt

 

[David L. Johnson]

On Sat, 18 Mar 2006 12:30:35 -0800, [email protected] wrote:

> Getting my first custom frame built [steel] and need to choose a fork.
> This machine will be built first for comfort then for speed. I just
> turned 58 and am 220lbs +/- so weight isn't really a factor. I am
> concerned about the safety of carbon forks even though they are
> ubiquitous.

Decent carbon forks have an excellent safety record; that should not be a
concern.

> I am assuming that the shock absorbing characteristics of carbon forks
> are based on equivalent tire sizes.

They are based on nothing but marketing, despite what others will tell you.

> Since carbon forks are not designed
> to accommodate tires 28mm or larger

Some are. Shop around. My road bike fork will certainly accommodate a
28mm tire, and maybe a bit larger. Not with a fender, though. My
tandem has a (cross) carbon fork as well, which will accommodate a very
big tire. But that might not work with your frame.

> [the kind I prefer] would a steel
> fork with a 28 or 32mm tire be just as comfortable and shock absorbing
> [not to mention cheaper] than a carbon fork with a 25mm tire?

Steel forks are no more likely to be big enough for your tires than a
carbon one. They are IMO indistinguishable from carbon in terms of "shock
absorbing", but weigh about a pound more.

> Just
> read something about the larger tires having less?! rolling resistance
> than the smaller ones.

Only at the same pressure, and you do not ride wider tires at the same
pressure as narrower ones. That data is bull.

> What about aerodynamics. How much of this
matters
> at 15mph +/-

Obviously a fatter tire is less aerodynamic than a thin one. Same applies
to riders, but rider width matters a whole lot more than tire width. None
of it matters at 15mph. Well, rider width does.

--

David L. Johnson

__o | When you are up to your ass in alligators, it's hard to remember
_`\(,_ | that your initial objective was to drain the swamp. -- LBJ
(_)/ (_) |

 

[[email protected]]

Dear Stan, & list:

Most guys custom-building road frames will do forks as well. If your
builder doesn't, you could post a request on the framebuilders list -
[email protected] - and hook up. A good steel fork will cost
about the same as a top of the line carbon unit.

A lot of machers are using the Pacenti flat fork crown with Columbus
legs bent to your taste and Campy, Pacenti or (my fave) Henry James
stainless dropouts.

good luck

jn

"Thursday"

 

[Nate Knutson]

David L. Johnson wrote:
> On Sat, 18 Mar 2006 12:30:35 -0800, [email protected] wrote:
>
> > Getting my first custom frame built [steel] and need to choose a fork.
> > This machine will be built first for comfort then for speed. I just
> > turned 58 and am 220lbs +/- so weight isn't really a factor. I am
> > concerned about the safety of carbon forks even though they are
> > ubiquitous.
>
> Decent carbon forks have an excellent safety record; that should not be a
> concern.

Unless you crash.

 

[John Forrest Tomlinson]

On 19 Mar 2006 00:31:25 -0800, "Nate Knutson" <[email protected]>
wrote:

>
>David L. Johnson wrote:
>> On Sat, 18 Mar 2006 12:30:35 -0800, [email protected] wrote:

>> Decent carbon forks have an excellent safety record; that should not be a
>> concern.
>
>Unless you crash.

What does that mean?

JT

****************************
Remove "remove" to reply
Visit http://www.jt10000.com
****************************

 

[Nate Knutson]

John Forrest Tomlinson wrote:
> On 19 Mar 2006 00:31:25 -0800, "Nate Knutson" <[email protected]>
> wrote:
>
> >
> >David L. Johnson wrote:
> >> On Sat, 18 Mar 2006 12:30:35 -0800, [email protected] wrote:
>
> >> Decent carbon forks have an excellent safety record; that should not be a
> >> concern.
> >
> >Unless you crash.
>
> What does that mean?
>
> JT

Carbon forks can get damaged/weakened from crashes, overloads, or other
abuse, not show any signs, and fail catastrophically. It's not epidemic
at this point but it does happen, and applies to all carbon forks made
as far as I know. Responsible makers and sellers of carbon forks will
generally say the same thing. The problem, of course, is that over the
years bikes often get crashed.

That damage can be hidden and cause spontaneous failure is true for any
material, but at least with well-made steel forks it's very rare.

 

[Ozark Bicycle]

Nate Knutson wrote:
> John Forrest Tomlinson wrote:
> > On 19 Mar 2006 00:31:25 -0800, "Nate Knutson" <[email protected]>
> > wrote:
> >
> > >
> > >David L. Johnson wrote:
> > >> On Sat, 18 Mar 2006 12:30:35 -0800, [email protected] wrote:
> >
> > >> Decent carbon forks have an excellent safety record; that should not be a
> > >> concern.
> > >
> > >Unless you crash.
> >
> > What does that mean?
> >
> > JT
>
> Carbon forks can get damaged/weakened from crashes, overloads, or other
> abuse, not show any signs, and fail catastrophically.


It should be pointed out that if a sponsored racer crashes a CF fork or
frame, the bike might well be replaced on the spot. In any case, it
will not be ridden the next day, when it is relegated to the scrap heap
even if there are no visible problems. How many recreational cyclists
can afford to do that?


> It's not epidemic
> at this point but it does happen, and applies to all carbon forks made
> as far as I know. Responsible makers and sellers of carbon forks will
> generally say the same thing. The problem, of course, is that over the
> years bikes often get crashed.
>
> That damage can be hidden and cause spontaneous failure is true for any
> material, but at least with well-made steel forks it's very rare.

IOW, think long and hard about how much risk you are willing to take
for the sake of saving 8-12oz. As has been pointed out earlier, the
"shock absorbing" aspect of a CF fork is pretty much pure bunk.

 

[jim beam]

Ozark Bicycle wrote:
> Nate Knutson wrote:
>
>>John Forrest Tomlinson wrote:
>>
>>>On 19 Mar 2006 00:31:25 -0800, "Nate Knutson" <[email protected]>
>>>wrote:
>>>
>>>
>>>>David L. Johnson wrote:
>>>>
>>>>>On Sat, 18 Mar 2006 12:30:35 -0800, [email protected] wrote:
>>>
>>>>>Decent carbon forks have an excellent safety record; that should not be a
>>>>>concern.
>>>>
>>>>Unless you crash.
>>>
>>>What does that mean?
>>>
>>>JT
>>
>>Carbon forks can get damaged/weakened from crashes, overloads, or other
>>abuse, not show any signs, and fail catastrophically.
>
>
>
> It should be pointed out that if a sponsored racer crashes a CF fork or
> frame, the bike might well be replaced on the spot. In any case, it
> will not be ridden the next day, when it is relegated to the scrap heap
> even if there are no visible problems. How many recreational cyclists
> can afford to do that?
>
>
>
>>It's not epidemic
>>at this point but it does happen, and applies to all carbon forks made
>>as far as I know. Responsible makers and sellers of carbon forks will
>>generally say the same thing. The problem, of course, is that over the
>>years bikes often get crashed.
>>
>>That damage can be hidden and cause spontaneous failure is true for any
>>material, but at least with well-made steel forks it's very rare.
>
>
> IOW, think long and hard about how much risk you are willing to take
> for the sake of saving 8-12oz. As has been pointed out earlier, the
> "shock absorbing" aspect of a CF fork is pretty much pure bunk.
>
like many societal ills, such fear & loathing can only come from
ignorance. fact: carbon is considerably stronger than steel. fact:
carbon has considerably better fatigue resistance than steel.

translation for the unsure: 1. any crash that writes off a carbon fork
will write off a steel fork. 2. the carbon fork will take more abuse
for longer than the steel fork.

you all need a dose of reality.

 

[John Forrest Tomlinson]

On 19 Mar 2006 07:57:52 -0800, "Ozark Bicycle"
<[email protected]> wrote:

>
>Nate Knutson wrote:
>> John Forrest Tomlinson wrote:
>> > On 19 Mar 2006 00:31:25 -0800, "Nate Knutson" <[email protected]>
>> > wrote:
>> >
>> > >
>> > >David L. Johnson wrote:
>> > >> On Sat, 18 Mar 2006 12:30:35 -0800, [email protected] wrote:
>> >
>> > >> Decent carbon forks have an excellent safety record; that should not be a
>> > >> concern.
>> > >
>> > >Unless you crash.
>> >
>> > What does that mean?
>> >
>> > JT
>>
>> Carbon forks can get damaged/weakened from crashes, overloads, or other
>> abuse, not show any signs, and fail catastrophically.
>
>It should be pointed out that if a sponsored racer crashes a CF fork or
>frame, the bike might well be replaced on the spot. In any case, it
>will not be ridden the next day, when it is relegated to the scrap heap
>even if there are no visible problems. How many recreational cyclists
>can afford to do that?

You're really starting to sound batty bringing up "sponsored racers"
getting stuff "replaced on the spot" as if that's relevant here. You
are obssessed with some sort of "haves" and "have nots" in cycling and
the perception of some sort of conspiracy by the racers to foist
terribly risky stuff on other people. Bizarre.

JT

****************************
Remove "remove" to reply
Visit http://www.jt10000.com
****************************

 

[John Forrest Tomlinson]

On 19 Mar 2006 07:57:52 -0800, "Ozark Bicycle"
<[email protected]> wrote:


>IOW, think long and hard about how much risk you are willing to take
>for the sake of saving 8-12oz.

How much risk it it? I'm certain that carbon forks from a good
manufactuer nowadays are as safe as steel forks of about 20 years ago.
I've seen at least one broken steel steerer tube (which *caused* a
crash), for example, but never seen a carbon fork fail except as the
result of a crash.

In sum -- you're a scare-monger.

JT


****************************
Remove "remove" to reply
Visit http://www.jt10000.com
****************************

 

[John Forrest Tomlinson]

On 19 Mar 2006 07:57:52 -0800, "Ozark Bicycle"
<[email protected]> wrote:


>It should be pointed out that if a sponsored racer crashes a CF fork or
>frame, the bike might well be replaced on the spot. In any case, it
>will not be ridden the next day, when it is relegated to the scrap heap
>even if there are no visible problems. How many recreational cyclists
>can afford to do that?

Well, don't forget the many posers out their who almost take glee in
wrecking fragile equipment that offers little or no benefit, just so
they can buy something newer and fancier to keep up the delusional (to
themselves and other people) that they really "need" the latest and
greatest stuff.

Of course you see through their folly, but not everyone does. Some of
the posers aren't even aware of it themselves.

JT

****************************
Remove "remove" to reply
Visit http://www.jt10000.com
****************************

 

[Peter Cole]

[email protected] wrote:
> Getting my first custom frame built [steel] and need to choose a fork.
> This machine will be built first for comfort then for speed. I just
> turned 58 and am 220lbs +/- so weight isn't really a factor. I am
> concerned about the safety of carbon forks even though they are
> ubiquitous. So I want a great and inspiring ride and value for money.

CF is the undisputed champ for strength to weight, which makes it the
perfect material for high performance bike frames. It also has superior
fatigue strength to any other material used to make frames. The only two
drawbacks to CF are the expense and poor impact strength. Impact
strength is not much of an issue anywhere on a bike except for the fork.
I don't think the weight savings justify the impact liability in that
one application, otherwise, CF is great. I think the ideal bike would be
almost all CF except the fork.

 

[Michael Press]

In article <[email protected]>,
John Forrest Tomlinson <[email protected]> wrote:

> On 19 Mar 2006 07:57:52 -0800, "Ozark Bicycle"
> <[email protected]> wrote:
>
>
> >IOW, think long and hard about how much risk you are willing to take
> >for the sake of saving 8-12oz.
>
> How much risk it it? I'm certain that carbon forks from a good
> manufactuer nowadays are as safe as steel forks of about 20 years ago.
> I've seen at least one broken steel steerer tube (which *caused* a
> crash), for example, but never seen a carbon fork fail except as the
> result of a crash.
>
> In sum -- you're a scare-monger.

The difference between steel and two phase carbon fiber &
resin as a structural material is the failure mode. It is
true that carbon fiber structural members show less
outward indication of damage than do steel structural
members. A damaged steel frame will start to feel loose
when damaged, and keep getting more loose until it fails,
giving the rider plenty of time to dismount. Carbon fiber
does not fail in this way. Damage is difficult, or
impossible to discover. It feels fine until it suddenly
disassociates into two pieces.

One of my steel frames was damaged in a collision. Not
knowing it was damaged, I rode a couple days with no
indication of damage; then felt it getting loose,
inspected, and found the crack.

--
Michael Press

 

[jim beam]

Michael Press wrote:
> In article <[email protected]>,
> John Forrest Tomlinson <[email protected]> wrote:
>
>
>>On 19 Mar 2006 07:57:52 -0800, "Ozark Bicycle"
>><[email protected]> wrote:
>>
>>
>>
>>>IOW, think long and hard about how much risk you are willing to take
>>>for the sake of saving 8-12oz.
>>
>>How much risk it it? I'm certain that carbon forks from a good
>>manufactuer nowadays are as safe as steel forks of about 20 years ago.
>>I've seen at least one broken steel steerer tube (which *caused* a
>>crash), for example, but never seen a carbon fork fail except as the
>>result of a crash.
>>
>>In sum -- you're a scare-monger.
>
>
> The difference between steel and two phase carbon fiber &
> resin as a structural material is the failure mode. It is
> true that carbon fiber structural members show less
> outward indication of damage than do steel structural
> members.

that's true up to a point, but two things:

1. carbon doesn't suddenly turn to dust. it tears apart just like wood.

2. carbon failure is almost /always/ accompanied by sound. again, just
like failing wood. if your carbon frame or fork is braking and
cracking, get off immediately.

> A damaged steel frame will start to feel loose
> when damaged, and keep getting more loose until it fails,
> giving the rider plenty of time to dismount. Carbon fiber
> does not fail in this way.

not necessarily so. it can/does indeed get "loose" giving the rider
time to dismount /if/ the rider's paying attention to what's going on.

> Damage is difficult, or
> impossible to discover. It feels fine until it suddenly
> disassociates into two pieces.

see above.

>
> One of my steel frames was damaged in a collision. Not
> knowing it was damaged, I rode a couple days with no
> indication of damage; then felt it getting loose,
> inspected, and found the crack.
>
"looseness" in a steel frame is /always/ due to cracking. that's
fatigue, and carbon is not anywhere near as susceptible as steel. if
carbon does crack, it can still bear load the same way cracked steel can
until it reaches failure point. the trick is to /not/ ignore the
warning signs as it creaks and groans it way to failure.

regarding impact strength, back in the beginning of february when i
smashed my wheels potholing, my carbon fork survived the impact
perfectly. it's an old look, one of their first carbon forks, and
tests, as described elsewhere in this thread, without trouble. so i'm
continuing to ride it. based on my past experience crashing steel
forks, i'm confident a steel fork in the same impact would have bent.
now, not all forks are created equal, and i'm certain one of those
defective kestrels would have failed, but the point is, carbon doesn't
suddenly fail any more than steel does. and its superior strength and
fatigue resistance, when fabricated properly, ensures it will survive
hardships steel just can't.

 

[Andrew Price]

Peter Cole writes -

> The only two drawbacks to CF are the expense and poor impact strength.
> Impact strength is not much of an issue anywhere on a bike except for the
> fork.

Anecdotal obeservations only, but in 10 years of cycling I have seen two cf
forks fail from sticks getting caught in the spokes and shearing off one or
both legs of the fork. Unhappy times in each case for the rider.

It occurs to me that they may not be very well protected for a sudden impact
of the type I describe.

That said, I do like riding a cf fork - but some additional care in
operation may be warranted.

best, Andrew

 

[Ozark Bicycle]

John Forrest Tomlinson wrote:
> On 19 Mar 2006 07:57:52 -0800, "Ozark Bicycle"
> <[email protected]> wrote:
>
>
> >IOW, think long and hard about how much risk you are willing to take
> >for the sake of saving 8-12oz.
>
> How much risk it it? I'm certain that carbon forks from a good
> manufactuer nowadays are as safe as steel forks of about 20 years ago.
> I've seen at least one broken steel steerer tube (which *caused* a
> crash), for example, but never seen a carbon fork fail except as the
> result of a crash.
>

"never seen a carbon fork fail except as the result of a crash", eh? I
notice that you, as is your habit, have deceptively snipped my post.

Here's the original:

http:tinyurl.com/hc2pw

Now read it. Do you now see that Nate's post and my reply are
specifically *about crash damage*, twit? Crash damage that may not
result in immediate failure, but can somtine later.


> In sum -- you're a scare-monger.
>

In sum, you're just another useless Usenet asshole engaging in
deceptive tactics in a pathetic attempt to score "points". But that's
not news, is it?

 

[Ozark Bicycle]

Ozark Bicycle wrote:
> John Forrest Tomlinson wrote:
> > On 19 Mar 2006 07:57:52 -0800, "Ozark Bicycle"
> > <[email protected]> wrote:
> >
> >
> > >IOW, think long and hard about how much risk you are willing to take
> > >for the sake of saving 8-12oz.
> >
> > How much risk it it? I'm certain that carbon forks from a good
> > manufactuer nowadays are as safe as steel forks of about 20 years ago.
> > I've seen at least one broken steel steerer tube (which *caused* a
> > crash), for example, but never seen a carbon fork fail except as the
> > result of a crash.
> >
>
> "never seen a carbon fork fail except as the result of a crash", eh? I
> notice that you, as is your habit, have deceptively snipped my post.
>
> Here's the original:
>
> http:tinyurl.com/hc2pw
>
Sorry: http://tinyurl.com/hc2pw


> Now read it. Do you now see that Nate's post and my reply are
> specifically *about crash damage*, twit? Crash damage that may not
> result in immediate failure, but can somtine later.
>
>
> > In sum -- you're a scare-monger.
> >
>
> In sum, you're just another useless Usenet asshole engaging in
> deceptive tactics in a pathetic attempt to score "points". But that's
> not news, is it?

 

[John Forrest Tomlinson]

On 19 Mar 2006 14:38:46 -0800, "Ozark Bicycle"
<[email protected]> wrote:

>
>John Forrest Tomlinson wrote:
>> On 19 Mar 2006 07:57:52 -0800, "Ozark Bicycle"
>> <[email protected]> wrote:
>>
>>
>> >IOW, think long and hard about how much risk you are willing to take
>> >for the sake of saving 8-12oz.
>>
>> How much risk it it? I'm certain that carbon forks from a good
>> manufactuer nowadays are as safe as steel forks of about 20 years ago.
>> I've seen at least one broken steel steerer tube (which *caused* a
>> crash), for example, but never seen a carbon fork fail except as the
>> result of a crash.
>>
>
>"never seen a carbon fork fail except as the result of a crash", eh? I
>notice that you, as is your habit, have deceptively snipped my post.
>
>Here's the original:
>
>http:tinyurl.com/hc2pw
>
>Now read it. Do you now see that Nate's post and my reply are
>specifically *about crash damage*, twit? Crash damage that may not
>result in immediate failure, but can somtine later.

Sorry,I wasn't clear. I meant the fork failed *during* the crash --
the rider was crashing anyway and the fact that the fork was CF did
not contribute to the crash happening. The fear-mongering about CF
makes it seem as if the rider is more likely to crash simply from
having a CF fork (supposedly due to weakness or being weakend in an
earlier crash). That's what I find hard to believe.

It's like the old worry about toe clips (and more recently about
clipless pedals) where someone says "Aren't those things dangerous?
What happens when you crash?" The proper response is "You crash."

JT



****************************
Remove "remove" to reply
Visit http://www.jt10000.com
****************************

 

[Chalo]

jim beam wrote:
>
> 1. any crash that writes off a carbon fork will write off a steel fork.

Bull. Even if they were built to withstand equivalent loads (and
remember, most bike steels become _stronger_ after an overload
failure), abrasions can ruin a CFRP fork when its steel counterpart
would be only cosmetically damaged. In my opinion, carbon-plastic
forks are unsuitable even for routine locking to public bike racks,
based on the wear patterns that can be observed on the paint of many
transportational bikes.

> 2. the carbon fork will take more abuse for longer than the steel fork.

Sorry, but you really have to torture the definition of "abuse" to give
that statement any veracity. Coddle it like an airplane part, and you
have a point that a CFRP fork may display greater fatigue resistance to
riding forces than a steel fork. Throw in the assortment of dings and
gouges that are likely to adorn a well-seasoned bike in the real world,
and your assertion becomes hogwash.

> you all need a dose of reality.

Speak for yourself. CFRP may make a fine Formula One car, but would
you use it to build a pickup truck? OK, maybe _you_ would, but would a
reasonable person?

Chalo Colina