Carbon forks + worth the money?

[Pete Biggs]

Terry Morse wrote:
> Gary Young wrote:
>
>>> http://www.sheldonbrown.com/rinard_forktest.html
>>
>> I don't think that page establishes your point.
>
> If you look beyond the conjecture and look only at the test data

The test is not appropriate for measuring the effect of small bumps and vibration.

"carbon is known to damp vibrations about ten times better than the metals. This damping is the
reason carbon forks can be both stiff and comfortable. You will still get the jolt of the big bumps
with a stiff carbon fork, but the vibrations will be decreased"
- Damon Rinard

~PB

 

[Gary Young]

Terry Morse <[email protected]> wrote in message
news:<[email protected]>...
> Gary Young wrote:
>
> > > "Truthfully, the differences between forks are pretty small. Nice light wheels make a much
> > > more noticeable difference. Padded handlebar tape or slightly more or less air pressure make
> > > about as noticeable a difference as a new fork, in my experience."
> > >
> > > http://www.sheldonbrown.com/rinard_forktest.html
> >
> > I don't think that page establishes your point.
>
> If you look beyond the conjecture and look only at the test data, it establishes the point nicely.
> Compare the deflection of a fork to that of an inflated tire, and consider how much sensitivity
> one would need to tell the difference from one fork to another. A typical tire under the force
> used in the above test would deflect about 2.7 cm, whereas the forks tested ranged from 0.3-0.5 cm
> inthe longitudianal direction. A difference of 0.2 cm would be nearly impossible to detect, being
> only about 6% of the total deflection. Some claim they can feel that difference. I say those
> people are kidding themselves.

I see your point. Thanks for the clarification.

 

[Jay Hill]

Terry Morse wrote:
> Gary Young wrote:
>
>
>>>"Truthfully, the differences between forks are pretty small. Nice light wheels make a much more
>>>noticeable difference. Padded handlebar tape or slightly more or less air pressure make about as
>>>noticeable a difference as a new fork, in my experience."
>>>
>>>http://www.sheldonbrown.com/rinard_forktest.html
>>
>>I don't think that page establishes your point.
>
> If you look beyond the conjecture and look only at the test data, it establishes the point nicely.

You don't seem to acknowledge the difference between shock absorption and vibration damping.

 

[Corey Green]

Terry Morse <[email protected]> wrote in message
news:<[email protected]>...
> Dave no 1 wrote:
>
> > I have recently replaced my Hartson steel forks with a set of Neuville sx6 carbon forks and I
> > am thouroughly dissapointed. Yes they are lighter (slightly) but I can notice no diferrence in
> > the ride.
>
> You had unrealistic expectations. Carbon, steel, aluminum, scandium, unobtanium: none of these
> materials in a fork will change the way a bike rides. They all essentially produce a rigid fork.

You are correct, they all produce an essentially rigid fork. However, I think what we are debating
is the difference in the specific rigidity of a fork.

Personally I have ridden many different forks, as most people on this board have.

As an example:

A Reynolds 531 fork on the front of an older Falcon 531 frame produced a very rigid ride, though it
was still quite confortable and not overly jarring.

A Kinesis Aluminum fork on the front of an Aluminum Cannondale CAAD3 produced a ride that only a
lover of the old wagon trail could appreciate.

A Look HSC 1 fork on the front a few frames produced a ride that made me seasick when I stood to
pedal due to the flexibility in the fork.

All of these forks are intended to be rigid forks, but each have a different specific rigidity
producing very different ride qualities. Maybe these are extremes, but they each produced a
different ride on the front end of the bike.

Because carbon can be easily manipulated and made stiffer or more flexible it is the hardest
material to predict ride quality from. Just because it is carbon doesn't mean it automatically
changes the ride quality, but it does have the potential to change the ride quality. It is all
dependent on the engineering specifics of the manufacturer.

Corey

 

[Dave Lehnen]

Terry Morse wrote:

>
> If you look beyond the conjecture and look only at the test data, it establishes the point nicely.
> Compare the deflection of a fork to that of an inflated tire, and consider how much sensitivity
> one would need to tell the difference from one fork to another. A typical tire under the force
> used in the above test would deflect about 2.7 cm, whereas the forks tested ranged from 0.3-0.5 cm
> inthe longitudianal direction. A difference of 0.2 cm would be nearly impossible to detect, being
> only about 6% of the total deflection. Some claim they can feel that difference. I say those
> people are kidding themselves.
> --
> terry morse Palo Alto, CA http://www.terrymorse.com/bike/

2.7 cm of tire deflection with a 47.5 lb load?? That's over one inch of deflection, more than the
height of most road tires. If it was
3.7 mm, the fork deflection is significant.

Dave Lehnen

 

[Terry Morse]

Jay Hill <[email protected]> wrote:
>
> Terry Morse wrote:
>
> > If you look beyond the conjecture and look only at the test data, it establishes the point
> > nicely.
>
> You don't seem to acknowledge the difference between shock absorption and vibration damping.

Vibration damping? Carbon composite's damping properties are certainly better than steel, aluminum,
or titanium, but in a fork they all basically produce zero damping of road noise. If it's damping
you want, buy a fork with suspension.
--
terry morse Palo Alto, CA http://www.terrymorse.com/bike/

 

[Ed Ness]

"Terry Morse" <[email protected]> wrote in message:
>
> Same goes for the different materials that bikes are made of. Steel may flex a certain amount, but
> it is going to flex that amount differently than say AL. I'm no engineer, so it may take one to
> explain this better than I am trying to. I could be completely off base, but I think it makes
> sense. Having ridden steel, AL, and carbon bikes, with steel, carbon, and AL forks, they all ride
> differently, but you can make them ride similarly by manipulating the materials.
>
> Does this make sense to anyone else?
> > --
> > terry morse Palo Alto, CA http://www.terrymorse.com/bike/

There are two different components to a vibration system, a spring and a damper. In our fork
example, the overall stiffness of the fork defines the spring rate and the material properties of
the fork define the damping. The Rinard test, clearly shows that different forks DO have different
spring rates. From my personel experience, this difference of spring rate is noticable and
appreciable. Unfortuntely, the material damping effect on human comfort is harder to quantify. I
think it does help to some extent but not to the extent that the spring rate change does.

Again from personel experience (flame me if you must), I have two different forks that are clearly
on the soft side spring rate wise: a lugged crown fork using True Temper RCX blades and a Time
Equipe carbon (first generation). The steel fork will chatter under braking loads at slow speed as
the brake pads grip/release the braking surface (crappy hard anodized sidewall!) whereas the Time
fork will move around a lot in the similar situation and chatter a slight amount but not to the
extent of the steel fork. My blatent opinion is that the material damping properties of the carbon
in the Time fork help damp out some of this chattering motion the fork makes. Just one data point
here so take it for what it's worth.

Ed

 

[Michael James A]

So I've been trying to get my wife into road riding, and it is finally starting to happen. There is
one problem, and that is that she feels a bit scared riding next to cars. We think that one of the
problems may be the tires that are on her bike: Bontrager Race X Lite, folding, 700x23c.

I want to try replacing these tires with some more comfortable/stable and great handling ones. Flat
resistance is also important; she fears getting a flat 20 miles from home, even though I have
changed more than I want to admit.

Any advice on a very high quality, reassuring tire would be great. I assume we should be looking at
700x25 yes?

Thanks in advance, Michael

 

[Richard Ney]

Michael James Anderson writes:

> So I've been trying to get my wife into road riding, and it is finally starting to happen. There
> is one problem, and that is that she feels a bit scared riding next to cars. We think that one of
> the problems may be the tires that are on her bike: Bontrager Race X Lite, folding, 700x23c.
>
> I want to try replacing these tires with some more comfortable/stable and great handling ones.
> Flat resistance is also important; she fears getting a flat 20 miles from home, even though I have
> changed more than I want to admit.
>
> Any advice on a very high quality, reassuring tire would be great. I assume we should be looking
> at 700x25 yes?

Try Avocet FasGrip SL Road (forget Kevlar belt, that doesn't do much) 25mm tires. They come in
folding or wire bead. They're the best tires I've used. Sheldon Brown sells them; not a lot of shops
do; Avocet might sell them to you directly.

http://www.sheldonbrown.com/harris/ http://www.avocet.com/tirepages/carbon12_specs.html

 

[Harris]

"Michael James Anderson" wrote

> So I've been trying to get my wife into road riding, and it is finally starting to happen. There
> is one problem, and that is that she feels a bit scared riding next to cars. We think that one of
> the problems may be the tires that are on her bike: Bontrager Race X Lite, folding, 700x23c.
>
> I want to try replacing these tires with some more comfortable/stable and great handling ones.
> Flat resistance is also important; she fears getting a flat 20 miles from home, even though I have
> changed more than I want to admit.
>
> Any advice on a very high quality, reassuring tire would be great. I assume we should be looking
> at 700x25 yes?

I doubt that 2mm wider tires alone are going to make much of a difference. Is the bike twitchy? Is
she set up on it properly (bars high enough, not too stretched out)?

As for tires, try the widest slicks that will fit the frame, and experiment with inflation pressure.
If she's light, try less than the max rated pressure.

Art Harris

 

[Robin Hubert]

"Harris" <[email protected]> wrote in message
news:[email protected]...
>
> "Michael James Anderson" wrote
>
> > So I've been trying to get my wife into road riding, and it is finally starting to happen. There
> > is one problem, and that is that she feels a bit scared riding next to cars. We think that one
> > of the problems may
be
> > the tires that are on her bike: Bontrager Race X Lite, folding, 700x23c.
> >
> > I want to try replacing these tires with some more comfortable/stable
and
> > great handling ones. Flat resistance is also important; she fears
getting
> > a flat 20 miles from home, even though I have changed more than I want
to
> > admit.
> >
> > Any advice on a very high quality, reassuring tire would be great. I assume we should be looking
> > at 700x25 yes?
>
> I doubt that 2mm wider tires alone are going to make much of a difference. Is the bike twitchy? Is
> she set up on it properly (bars high enough, not
too
> stretched out)?

I think 2mm is significant. 2mm wider ain't much but 2mm more in diameter *is*.

>
> As for tires, try the widest slicks that will fit the frame, and
experiment
> with inflation pressure. If she's light, try less than the max rated pressure.

This is a good approach. 700x28's are pretty nice if you can fit them.

Robin Hubert

 

[Br]

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> > "Michael James Anderson" wrote

> > > I want to try replacing these tires with some more =
comfortable/stable
> and
> > > great handling ones. Flat resistance is also important; she fears
> getting
> > > a flat 20 miles from home, even though I have changed more than I =
want
> to
> > > admit.
> > >
> > > Any advice on a very high quality, reassuring tire would be great. =
I
> > > assume we should be looking at 700x25 yes?
> >

I used Continental Gator Skins 700x25. Their big--they seem bigger than = 25s--and I only got flats
when I left them on far too long.

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FONT-FAMILY: Arial">
<DIV><FONT size=3D2>> > "Michael James Anderson" = wrote<BR></FONT></DIV>
<DV><FONT size=3D2>> > > I want to try replacing these tires = with some=20 more
comfortable/stable<BR>> and<BR>> > > great handling = ones. =20 Flat
resistance is also important; she fears<BR>> getting<BR>> = > > a=20 flat 20 miles
from home, even though I have changed more than I = want<BR>>=20 to<BR>> > >
admit.<BR>> > ><BR>> > > Any = advice on a=20 very high quality, reassuring
tire would be great. I<BR>> > = >=20 assume we should be looking at 700x25
yes?<BR>> ><BR></FONT></DIV>
<DVI><FONT size=3D2>I used Continental Gator Skins 700x25. Their = big--they=20 seem bigger
than 25s--and I only got flats when I left them on far too=20 long.</FONT></DIV></BODY></HTML>

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