Are carbon curved forks going extinct?

[drgonzo]

The only curved forks I see widely available are the Columbus Minimal and Ritchey Comp. Neither one is offered in a tapered design. What gives?

[drgonzo]

Ok so now I'm going down the rabbit hole and I found this article that explains a few things, some I knew, some I didn't. But the take away seems to be that straight carbon forks are easier to manufacture than curved carbon forks.

https://physics.stackexchange.com/questions/270348/why-do-modern-bicycles-have-curved-front-wheel-forks

[ERK55]

Seven still makes curved carbon forks.
The Pegoretti Falz is also slightly curved.

[Mike Lopez]

Over the years we’ve made both styles and one is not more difficult to make or stronger than the other.

The article is speculative and not based on manufacturing experience.

BTW...We were the original source for Seven’s above mentioned fork ... ;)

[mcteague]

Over the years we’ve made both styles and one is not more difficult to make or stronger than the other.

The article is speculative and not based on manufacturing experience.

BTW...We were the original source for Seven’s above mentioned fork ... ;)

Interesting. When I bought my Seven 622 SLX, back in 2013, they told me the frame's carbon tubes were made by Rock West Composites in UT but they were cagey about where the 5E fork came from.

Tim

[tv_vt]

BTW...We were the original source for Seven’s above mentioned fork ... ;)

Are you referring to the 5e, Mike? I love that fork, and Seven doesn't sell it anymore.:mad: Don't suppose you have any in the warehouse, do you? (Like a 42mm rake long reach brake model...)

[Mike Lopez]

[QUOTE=mcteague;2673021]Interesting. When I bought my Seven 622 SLX, back in 2013, they told me the frame's carbon tubes were made by Rock West Composites in UT but they were cagey about where the 5E fork came from.

The original Reynolds Composites was sold to MQC which later split into Rock West and the wheel company know as Reynolds. Don't know where Seven's fork went after my crews involvement.

And to the other gents question. No old stock that I'm aware of.

[Mark McM]

Ok so now I'm going down the rabbit hole and I found this article that explains a few things, some I knew, some I didn't. But the take away seems to be that straight carbon forks are easier to manufacture than curved carbon forks.

https://physics.stackexchange.com/questions/270348/why-do-modern-bicycles-have-curved-front-wheel-forks

Unfortunately, there's a lot wrong in the answers given in the above article. A straight fork can give just as much compliance as a curved fork; straight forks do not have "sharp turns" that create stress concentrations; and as Mike Lopez pointed out, its no more difficult to create a curved carbon fork than a straight carbon fork.

[zzy]

There's no real reason to use steel-style rake with a carbon fork as they don't flex like that. In fact most modern carbon forks are so sturdy the fork blades barely flex at all. And my favorite steel fork (of many) is a straight blade IF unicrown fork.

[drgonzo]

Thanks, some interesting info in this thread but I'm still left wondering why curved forks are almost non-existent? Several of the leading mfgrs don't carry a single curved fork - Enve, whisky, 3T, etc.

Is this a performance thing? Are straight forks superior? Are they cheaper to manufacture? Am I just part of a very small market of users that prefers the look and ride of curved forks?

[Old School]

straight forks do not have "sharp turns" that create stress concentrations

I strongly disagree. No offense, we may just have a difference in the perception of terms.

distributed stress:

I
(

not as evenly distributed stress:

I
\

source: engineer whose senior project was stress /strain curves of fiberglass laminates

[Mark McM]

I strongly disagree. No offense, we may just have a difference in the perception of terms.


distributed stress:

(
)

not as evenly distributed stress"

/
\

source: engineer whose senior project was stress /strain curves of fiberglass laminates

It's not quite as simple as that. The largest loads are at/near the crown, and are a combination of bending and torsion. Carbon forks, being made of layers of carbon strands, tend to have smooth transitions in this area. There isn't much difference in the shapes of forks in this area between straight and curved blades. Besides which, the sharpest transition in the fork is typically at the junction between the crown and the steerer, and this junction is the same regardless of whether the blades are straight or curved.

source: engineer whose master thesis was on stress/strain analysis of flexural structures for multi-axis load sensors.

[NYCfixie]

source: engineer whose senior project was stress /strain curves of fiberglass laminates

source: engineer whose master thesis was on stress/strain analysis of flexural structures for multi-axis load sensors.


Is their a PHd in the house who can be the tie breaker?

And I am sure you both know that academic papers written using other academic papers as sources is not always the same as actual lab work or real world testing (not implying either of you have not done this pre or post writing your papers).

[Mike Lopez]

Thanks, some interesting info in this thread but I'm still left wondering why curved forks are almost non-existent? Several of the leading mfgrs don't carry a single curved fork - Enve, whisky, 3T, etc.

Is this a performance thing? Are straight forks superior? Are they cheaper to manufacture? Am I just part of a very small market of users that prefers the look and ride of curved forks?

Performance...No. Superior...No. Cheaper to make...No. Mostly it's a matter of current fashion trends. Perhaps with the exception of disc forks and thru axles. Those might be a bit easier to do with fatter, straighter, legs.

Regarding your previous question about tapered steerers along with curved blades. Having made both, I'm willing to bet the manufacturers aren't willing to spend the money on new tooling for what they may perceive as a diminishing market. Molds and new processes cost money. It's a business decision. If enough folks wanted them they'd do it. But they don't. I've had to make that decision myself many times over the years.

[Old School]

It's not quite as simple as that. The largest loads are at/near the crown, and are a combination of bending and torsion. Carbon forks, being made of layers of carbon strands, tend to have smooth transitions in this area. There isn't much difference in the shapes of forks in this area between straight and curved blades. Besides which, the sharpest transition in the fork is typically at the junction between the crown and the steerer, and this junction is the same regardless of whether the blades are straight or curved.

source: engineer whose master thesis was on stress/strain analysis of flexural structures for multi-axis load sensors.

I'm not being argumentative, and certainly don't want to get into an escalating diploma measuring contest, but I think I can explain my contention in a different way.

Let's try this:

Assuming a 100% equal load, and each designed to have equal displacement ("flex") at the same load.

Assuming we agree that "the sharpest transition" is also the point of the highest stress concentration.

A curved fork will have less stress at the singular highest stressed point, by virtue of the curved legs "flexing".

A straight fork will have more stress at the singular highest stressed point, by virtue of the straight legs not "flexing".

Thanks.

[Mark McM]

I'm not being argumentative, and certainly don't want to get into an escalating diploma measuring contest, but I think I can explain my contention in a different way.

Let's try this:

Assuming a 100% equal load, and each designed to have equal displacement ("flex") at the same load.

Assuming we agree that "the sharpest transition" is also the point of the highest stress concentration.

A curved fork will have less stress at the singular highest stressed point, by virtue of the curved legs "flexing".

A straight fork will have more stress at the singular highest stressed point, by virtue of the straight legs not "flexing".

Thanks.

I think you'll find that there is little flex in the curved portion of the fork, because it tends to be closest dropout (and thus have a small moment arm). Bigger factors in fork stress are fork width/diameter, wall thickness, and fiber orientation. Any contribution of blade curve pales in comparison.

(Also of note is that any sharp turns required by using straight blades is at/in the crown. Yet carbon forks typically don't break at the crown, they more commonly break in the blades below the crown - which is usually a straight portion of the blades, even if they do have a curve at the bottom.

[drgonzo]

Performance...No. Superior...No. Cheaper to make...No. Mostly it's a matter of current fashion trends. Perhaps with the exception of disc forks and thru axles. Those might be a bit easier to do with fatter, straighter, legs.

Regarding your previous question about tapered steerers along with curved blades. Having made both, I'm willing to bet the manufacturers aren't willing to spend the money on new tooling for what they may perceive as a diminishing market. Molds and new processes cost money. It's a business decision. If enough folks wanted them they'd do it. But they don't. I've had to make that decision myself many times over the years.

Thanks Mike, this answers my question exactly! Also confirms my feeling/disappointment that the move toward straight blade forks is due to market demand. I suppose trends go in cycles (no pun intended) and maybe I just need to wait for the curved forks to come back en vogue. :cool:

[Hawker]

As a rider of small frames who has always had some issues with toe overlap...I appreciate the option of a curved fork.

[jtbadge]

As a rider of small frames who has always had some issues with toe overlap...I appreciate the option of a curved fork.

given the same rake, wouldn't a curved fork create more toe overlap than a straight fork?

[steamer]

As a rider of small frames who has always had some issues with toe overlap...I appreciate the option of a curved fork.

The shape of the blades doesn't determine the fork rake and the resulting clearance between the wheel and toe.

[happycampyer]

Is their a PHd in the house who can be the tie breaker?
I would say Mike Lopez’ comments pretty much do that. He’s only been building (some of the finest) carbon forks for 25 years or so.

[Wakatel_Luum]

From an aesthetic point of view curved forks to me are more appealing, I blame Colnago for the ugliness of today’s forks...

This is also another reason I’m reverting back to lightweight steel, to me it also feels better. Particularly when out of the saddle stomping...the weight penalty I can live with.

[BdaGhisallo]

From an aesthetic point of view curved forks to me are more appealing, I blame Colnago for the ugliness of today’s forks...

This is also another reason I’m reverting back to lightweight steel, to me it also feels better. Particularly when out of the saddle stomping...the weight penalty I can live with.

And the engineers at Ferrari. They were the ones who planted the seed in Colnago's head for a straight bladed fork.

[Waterlogged]

Straight vs curved forks is a demand driven function based upon aesthetics. They both connect the front wheel to the frame and are built to be rigid without abusing the rider. Carbon forks can be easy designed to achieve that requirement.

[Black Dog]

given the same rake, wouldn't a curved fork create more toe overlap than a straight fork?

No. The horizontal distance to the axle from the is the same for the same rake. This is what rake is. The shape of the fork is immaterial.

[jtbadge]

No. The horizontal distance to the axle from the is the same for the same rake. This is what rake is. The shape of the fork is immaterial.

Haha, because of course the toe overlaps the wheel and not the fork. Whoops!

[Black Dog]

Haha, because of course the toe overlaps the wheel and not the fork. Whoops!

I knew you would have your aha moment...all cool. ;)

[Hawker]

I knew you would have your aha moment...all cool. ;)

I'm not ashamed to admit my stupidity. But wouldn't a curved fork (think touring bikes of the 80s) lengthen the wheelbase and put the axel and the wheel further out from the pedal/foot thereby creating less overlap?

[tv_vt]

But wouldn't a curved fork (think touring bikes of the 80s) lengthen the wheelbase and put the axle and the wheel further out from the pedal/foot, thereby creating less overlap?

You're mixing apples and oranges. Front-Center distance mainly drives toe overlap, along with shoe size and crank length, and even cleat location. The curve of the fork blade doesn't have anything to do with it - could be straight blade or curved - the rake is the rake: front wheel ends up in the same place either way. However compare two bikes with differing front-centers and you'll see how it works. It's the distance from BB to front axle (eg. front-center) that drives toe overlap, keeping wheel diameter as a constant.

Yes, once a bike is built, changing between forks of different rakes will (slightly) change toe overlap distance, but not much. Will affect steering response, tho. I've fiddled with forks of different rakes a lot to get my desired front end stability (shooting for around 60-61mm trail).

[Wakatel_Luum]

And the engineers at Ferrari. They were the ones who planted the seed in Colnago's head for a straight bladed fork.

Damn that awesome car company and their beautiful red vehicles! 🚗

[9tubes]

Dunno, sure looks curved to me. :)

And it's so light it's levitating! Take my money!


.

[Hawker]

You're mixing apples and oranges. Front-Center distance mainly drives toe overlap, along with shoe size and crank length, and even cleat location. The curve of the fork blade doesn't have anything to do with it - could be straight blade or curved - the rake is the rake: front wheel ends up in the same place either way. However compare two bikes with differing front-centers and you'll see how it works. It's the distance from BB to front axle (eg. front-center) that drives toe overlap, keeping wheel diameter as a constant.

Yes, once a bike is built, changing between forks of different rakes will (slightly) change toe overlap distance, but not much. Will affect steering response, tho. I've fiddled with forks of different rakes a lot to get my desired front end stability (shooting for around 60-61mm trail).

Thanks tv and others here. I was forced to get out some paper, a ruler and a few other links....and I understand my mistake. Thanks very much for cluing me in.