Carbon fork = harshness?

[Jameshow]

Try pro 4 tyres - audaxer love them.

 

[ren531]

Just an update, tried a shorter stem, raised the stem 10mm and slightly lower tyre pressure up front and not perfect but a big improvement, less weight on my hands and less vibration coming through.

 

[Ajax Bay]

Just an update, tried a shorter stem, raised the stem 10mm and slightly lower tyre pressure up front and not perfect but a big improvement, less weight on my hands and less vibration coming through.

Moving your saddle back also, counter-intuitively, means less weight supported by your hands.
Tyre pressure delta (rear/front) should be typically 15psi different to reflect the different load on each wheel. One can check these loads (with help) by sitting in riding position eg hoods and putting first rear and then front wheel on bathroom scales.

 

[Fab Foodie]

Returning to this thread as considering buying the Spa Audax Carbon fork for my Rourke to replace the existing 853 fork.
Spa say their carbon fork absorbs road buzz better than their steel fork (and invited me to come and try a bike with both), so I trust their expertise in that respect.

We all get a bit dewy-eyed about the ride quality of steel, particularly older bikes and then forget that whilst they soak-up poor road surfaces they flex like there's no tomorrow as well. I have some old Holdsworths and others made in various 531 and on a twisty decent at anything close to 40mph they become very scary indeed, whereas the stiffer 853 carries-on unperturbed.
I have an 531 MTB, Saracen/Evans mid-80s with very curved forks which you expect to be shock-absorbing which will loosen your fillings.
So it's more complicated than Steel is a feather-bed and carbon is harsh or vice-versa, it depends how that material is employed too.

 

[Ajax Bay]

. . . considering buying the Spa Audax Carbon fork for my Rourke to replace the existing 853 fork.
Spa say their carbon fork absorbs road buzz better than their steel fork (and invited me to come and try a bike with both), so I trust their expertise in that respect.
. . . .the stiffer 853 carries-on unperturbed . . . .[steel v carbon] . . . it depends how that material is employed too.

So why are you considering replacing the unperturbed 853 fork, because your local poor road surfaces give you 'buzz'?
Are there data/science to support Spa Cycles' esteemed expertise? For the avoidance of doubt: I think they are great and provide service and stock that others don't.
Going googling offers this (YMMV):
"Since steel forks are more flexible, this means that they can absorb the vibrations picked up by your bike when traveling on rough roads; dampening the road bumps to offer you a smooth ride."
"Carbon forks are manufactured with greater stiffness than steel forks which enhances your bike’s efficiency and responsiveness."
The full differences between carbon and steel forks can be summarized in this table:

	Steel Fork	Carbon Fork
Compliance	More flexible	Less flexible, and more brittle
Resilience	Strong and resilient under majority of impacts	More brittle and prone to fractures on impact
Cost	Cheaper to buy and repair	More expensive to buy, and harder/more expensive to repair
Stiffness	Less stiffness, so less aerodynamic qualities	More stiff, and so more aerodynamic and suited for high-performance riding
Weight	Heavier than carbon forks	Lighter than steel forks

 

[cougie uk]

I'm not sure that article you've plucked is definitive.

CF can be made to create very stiff forks or comfortable forks.

I went from a 653 frame to a CF one with the same wheels tyres and groupset and the improvement in road comfort was very noticeable. And that was on a very race oriented frame.

 

[Smokin Joe]

Whatever this legendry "Road buzz" is, I've never experienced it on any bike, whether steel, alloy or carbon. The quality of the tyres and tubes and the pressures you run dictate 90% of the ride quality, no matter what the frame material.

Which is why I never bought inner tubes from Wilkinsons or the pound shop.

 

[Fab Foodie]

So why are you considering replacing the unperturbed 853 fork, because your local poor road surfaces give you 'buzz'?
Are there data/science to support Spa Cycles' esteemed expertise? For the avoidance of doubt: I think they are great and provide service and stock that others don't.
Going googling offers this (YMMV):
"Since steel forks are more flexible, this means that they can absorb the vibrations picked up by your bike when traveling on rough roads; dampening the road bumps to offer you a smooth ride."
"Carbon forks are manufactured with greater stiffness than steel forks which enhances your bike’s efficiency and responsiveness."
The full differences between carbon and steel forks can be summarized in this table:

	Steel Fork	Carbon Fork
Compliance	More flexible	Less flexible, and more brittle
Resilience	Strong and resilient under majority of impacts	More brittle and prone to fractures on impact
Cost	Cheaper to buy and repair	More expensive to buy, and harder/more expensive to repair
Stiffness	Less stiffness, so less aerodynamic qualities	More stiff, and so more aerodynamic and suited for high-performance riding
Weight	Heavier than carbon forks	Lighter than steel forks

For completeness:

https://spacycles.co.uk/m21b0s29p2625/SPA-CYCLES-Carbon-Alloy-Audax-Road-Fork
https://spacycles.co.uk/m21b0s29p3677/SPA-CYCLES-Steel-Road-Fork

So from their 2 test bikes one with each fork, they say that the Carbon is better/smoother and as a result that's what they end-up fitting to the majority of their Audax bikes.
Carbon forks are cheap too, try buying a set of 531 or Reynolds R blade forks with a 1 1/8th steerer or having a pair made (as they are generally not off the shelf) these days and they cost a few hundred quid and a bit.
The 350g weight saving is a bonus....
It's a punt I can afford as I can re-purpose one of the forks elsewhere.

Once done - I can add to the large body of anecdata....

 

[Ajax Bay]

So from their 2 test bikes one with each fork, they say that the Carbon is better/smoother and as a result that's what they end-up fitting to the majority of their Audax bikes.
Carbon forks are cheap too, try buying a set of 531 or Reynolds R blade forks with a 1 1/8th steerer or having a pair made (as they are generally not off the shelf) these days and they cost a few hundred quid and a bit.

I wonder if you have put your finger on it? Most frames are now made for a 1.125" steerer (or 1.25 > 1.125). So no point speccing a steel fork which would mean ££ more and supply problems.
'Not sure about a carbon fork, old chap!'
'Reduces road buzz Madam; much smoother'
'But you said it was stiffer.'
'Smoother, Madam; stiffer and smoother' @Fnaar
@cougie uk I'm sure that article I plucked is not definitive. Please offer better.

 

[Ajax Bay]

Wandering on another 'mission' in another place, I stumbled on these words of wisdom (from 2017):

Roll it back one step further and ask why we assume less stiff is less fast or less efficient or less anything, especially when it comes with some other benefit.

I've been part of testing where two 'identical' carbon frames with different layups showed a difference in BB stiffness of 2x and looking at the speed/power data from control riders on control courses, we found literally NO repeatable difference in speed for a given power under any of the test conditions including out of saddle climbing and out of corner sprinting (most interestingly the out of saddle climbing actually showed an almost statistically significant improvement in favor of the less stiff bike..but not quite).
Similarly we've built wheels with 2x difference in lateral stiffness for similar testing and unless there is rubbing of components, you just can't see anything in the data.

Stiffness is a popular proxy for 'fast' and 'efficient' but I think it's importance isn't as well understood as we might think.

---

http://www.SILCA.cc
Check out my podcast, inside stories from more than 20 years of product and tech innovation from inside the Pro Peloton and Pro Triathlon worlds!
http://www.marginalgainspodcast.cc

 

[Fab Foodie]

Wandering on another 'mission' in another place, I stumbled on these words of wisdom (from 2017):

Roll it back one step further and ask why we assume less stiff is less fast or less efficient or less anything, especially when it comes with some other benefit.

I've been part of testing where two 'identical' carbon frames with different layups showed a difference in BB stiffness of 2x and looking at the speed/power data from control riders on control courses, we found literally NO repeatable difference in speed for a given power under any of the test conditions including out of saddle climbing and out of corner sprinting (most interestingly the out of saddle climbing actually showed an almost statistically significant improvement in favor of the less stiff bike..but not quite).
Similarly we've built wheels with 2x difference in lateral stiffness for similar testing and unless there is rubbing of components, you just can't see anything in the data.

Stiffness is a popular proxy for 'fast' and 'efficient' but I think it's importance isn't as well understood as we might think.

---

http://www.SILCA.cc
Check out my podcast, inside stories from more than 20 years of product and tech innovation from inside the Pro Peloton and Pro Triathlon worlds!
http://www.marginalgainspodcast.cc

That I can believe to be true.
The main benefit I have found with stiffness in a bike is in the high speed handling and descending, they feel much more 'composed' if that's not bollocky talk.

 

[GuyBoden]

That I can believe to be true.
The main benefit I have found with stiffness in a bike is in the high speed handling and descending, they feel much more 'composed' if that's not bollocky talk.

I think you are correct, I've used and still have an old Reynold's 531 competition frame and it is too flexible, they made even more flexible versions called 531 Super Light and 531 Professional.

Too much flexibility and you can't put all your power down, but nice for pootling around Cheshire.

 

[Smokin Joe]

That I can believe to be true.
The main benefit I have found with stiffness in a bike is in the high speed handling and descending, they feel much more 'composed' if that's not bollocky talk.

A few years ago one of the mags got two then current pros to ride a couple of steel era race bikes to see what they thought of them. Both said they had been frightened to death on high speed descents by the whip in the frames when cornering.

 

[Ajax Bay]

A few years ago one of the mags got two then current pros to ride a couple of steel era race bikes to see what they thought of them. Both said they had been frightened to death on high speed descents by the whip in the frames when cornering.

Were the magazines replete with adverts from manufacturers selling steel framed bikes, I wonder?
Let's face it, a key characteristic you need to have nailed is "cornering on high speed descents". That, or decent brakes.

 

[Fredo76]

A few years ago one of the mags got two then current pros to ride a couple of steel era race bikes to see what they thought of them. Both said they had been frightened to death on high speed descents by the whip in the frames when cornering.

At my age, I want no part of verifying or disputing that! I'll just have to accept the judgement of history, that we old timers are indeed heroic. Maybe I'll get a t-shirt printed up: I survived descending Mt. Lemmon on a steel bicycle.