Lifespan of carbon forks?

[pq]

My best summer road bike is now 21 years old and has Mizuno carbon forks. The forks, I'm fairly sure are slightly newer than the bike, but I've had the bike for 18 years, so they're at least that old. The bike has done a lot of miles but has never been crashed and the forks are unmarked. 1" carbon forks are now fairly easy to get (Columbus do one which I have on another bike). So should I replace them?

The same bike also has a rare and, at the time, expensive WR Compositi carbon stem and some unbranded carbon bars. I guess if the forks need replacing, I should replace those too.

Unfortunately I have various other bikes with ancient carbon forks. My tourer has some of 2005 vintage, also unmarked and I have some 1st generation carbon Pace RC31s on a well used mountain bike. This could get expensive..

Any thoughts?

Thanks.

[tim-b]

Hi

"...carbon fiber essentially does not fatigue as long as the carbon-and-resin matrix is not damaged, age alone is not much of a guide..."

from https://www.velonews.com/gear/technical-faq-the-lifespan-of-your-carbon-fiber-racing-wheels/

The other issues with CF are galvanic corrosion between dissimilar materials, e.g. metal wheel dropouts bonded into a CF structure, and UV light. Manufacturers add neutral layers between the two materials and UV resistant clear coat/paint colours to prevent those problems

EDIT: this chap knows his stuff and you will find expert opinion in one of his videos https://www.youtube.com/channel/UCY9JUMYI54lLOHpb_zbIedQ
Regards
tim-b

[mig]

are the forks full carbon? fork blade and steerer?

or carbon blades bonded to alu steerer?

what sort of riding do you do? short trundles around on flat roads? hugely long alpine raids with heavy braking at each hairpin relying on the fork to save you from disappearing over the edge every few minutes?

do you clean and inspect the bike regularly?

i would probably ride the bike 'as is' and keep it under close watch but be especially cautious if i knew that i was going to put it under significant duress.

my best summer bike is 23 years old and made of columbus max. i don't even think about it breaking.

[pq]

They are full carbon. I got rid of all my alu steerer farbon corks long ago... I live near the Pyrenees, so you can imagine how it gets ridden. Well maintained but usually dirty - but I do check the fork pretty regularly. All my bikes are metal of one sort or another and I'm not worried about any of them, especially this one. It's just the old carbon components I have on some of my bikes.

[mig]

(1) lots of my riding used to be in the pennines of northern england. not the pyrenees but i could reach a fair clip coming down some descents...well above 50mph on open, busy roads.

(2) i had a fairly old bike with carbon forks that was cared for but relegated to commuting duties. this fork snapped on a climb at maybe 10mph and left me rolling in the road wondering what on earth had happened. the steerer had cracked.

if the bike in (2) had still been used for the style of riding in (1) then who knows what would have happened.

my advice would be to use a 'known good' bike if you're hurtling off the tops somewhere local to you. i guess that this is the problem with carbon. it can be tough, well cared for and long lasting, it can be poorly made and weak. it's hard to tell and you don't get much notice when it's had enough!

[pq]

I think I can be confident that these forks are not poorly made or weak - they would have broken long ago if they were. Mizuno forks are very high quality, as you'd expect on a frame which was probably the most expensive available 21 years ago. So in that sense I know this bike is "good", my question was more about age deterioration which tim b's post has dealt with quite well.

[slowster]

I think I can be confident that these forks are not poorly made or weak - they would have broken long ago if they were. Mizuno forks are very high quality, as you'd expect on a frame which was probably the most expensive available 21 years ago. So in that sense I know this bike is "good", my question was more about age deterioration which tim b's post has dealt with quite well.

I think in one of his videos Raoul Luescher mentions 20 years for the lifespan of a carbon frame/fork, but it was not an absolute rule or any assurance that people will get that sort of lifespan from their bike: some carbon parts might never last that long due to the quality of the materials used and/or the wear and tear in use, and others might conceivably exceed it. I think 20 years was based on when some resins can be expected to degrade.

What becomes increasingly clear the more of his videos you watch, is that you cannot simply rely on the brand reputation as a guarantee of fault free manufacture. Nor would I take the view that if there were a serious flaw in the manufacturing they would have broken long ago.

Incidentally, Luescher's own bike has Enve forks. He ordered three pairs of forks from Enve, ultrasound scanned them to assess which was the most fault free, and returned the other two. He commented that he would never ride a pair of forks that he had not scanned first.

I think that there are many aircraft flying with carbon components that are over 20 years old, but they are subject to higher manufacturing standards than bikes (including Mizuno), and very high standards of maintenance, including non-destructive testing.

I think there are two approaches to take with carbon forks: either treat them as a consumable and replace after a set period or mileage, e.g. maybe 10 or 15 years, or get them regularly ultrasound scanned once they reach a certain age and after any impacts, e.g. by a company like https://www.targetcomposites.co.uk/damage-inspection.

[Bonzo Banana]

When you look at the huge number of carbon fork recalls over the last 10 years or so I think a larger percentage were those that bonded an aluminium steerer with carbon fibre blades but not all. Carbon fibre forks will fatigue if there is a flaw in manufacturing, I guess a bit like steel in that it has an endurance limit where it won't fatigue but a manufacturing error might be of a type that will gradually increase in time so acts like fatigue. Many people also don't treat carbon fibre correctly so over-tighten fittings crushing the carbon fibre and weakening it plus finally abuse the bike may get in use i.e. fall over when parked or in a rack which might start the pseudo fatigue of those forks. As Luescher Technik has stated carbon fibre forks are much more dangerous than a carbon fibre frame because of how they fail often at high speed causing major injury or death especially if it leaves you on the road in the presence of road vehicles that will run over you like HGV's. Much safer to have a carbon fibre frame bike with steel or aluminium forks than an aluminium or steel frame bike with carbon fibre forks but you never see that in the marketplace.

Personally I feel carbon fibre forks are a performance component purely for riding when performance is critical I personally wouldn't use them for daily use especially as I'm a heavy rider in an area with very poor roads with plenty of potholes. I'm a huge fan of steel forks I just feel they are the ideal forks when lightness isn't a priority.

I see cheap road bikes made in Vietnam, Cambodia, Bangladesh etc using carbon fibre forks with an aluminium steerer and I would never trust those forks. Many of the big brands use the very cheapest factories for their entry level and mid-level models.

I remember seeing this image which is a photo on the Quest Composite site which makes carbon fibre frames and forks for Trek and Canyon as well I'm sure other brands. I look at those conditions and the fact the hair net is not properly worn and how dangerous it is if any dust or hairs etc fall get into the forks which can massively reduce their strength and cause fatigue. The company obviously has no issue with that image as its on their site so is probably an example of what they think are good conditions of their factory. I also remember a Canyon bike that failed on first ride straight out of the box that was reported in a forum and how disappointed the buyer was with the quality which clearly wasn't scanned as Canyon claims. The bike industry is very much like the cosmetics industry its all about selling a dream or lifestyle rather than an engineering product.

It should be pointed out that carbon fibre is expensive because of the huge manual processes that involve people which leads to many more possibilities of poor quality perversely steel frames in modern Asian factories are often manufactured by robots and have an extremely low failure rate the robots achieve fantastic consistent welds in very controlled conditions. It's the oldest frame material but that means the processes of manufacturing such frames are at the most advanced state for quality and consistency and value of course.

[pq]

Thanks all.

There's some contradictory stuff in the various links here, some saying carbon has a theoretically infinite life, others saying not. However what's very clear is that the major issue is damage and while the forks have never been crashed and are unmarked, there could be some deterioration arising from an invisible manufacturing fault.

I'd be more than happy to pay someone like target composites to inspect them, but I'm in France so getting them there would be difficult. I think what I need to do is find someone who offers the same service in France. If anyone knows of anything.... Of course that depends on price, the 1" full carbon columbus forks I bought last year for one of my other bikes weren't that expensive, so maybe it makes most sense just to assume the worst and replace them.

[pq]

I've just emailed target who were very helpful and swift to reply. They want £90 to inspect the fork, which I think is reasonable, but by the time I've paid that and two sets of (international) postage, it'll be over 50% of the cost of a new fork, so buying new seems like the way to go.

[tim-b]

Hi
Yes, that is an inescapable fact...testing costs. Unless you have something that you want to preserve then new is cheaper, just be aware that you may be swapping proven and untested for unproven and untested
Regards
tim-b

[slowster]

testing costs. Unless you have something that you want to preserve then new is cheaper

Although I suggested myself that carbon forks should potentially be viewed as a consumable, it's depressing that it can be more cost effective to buy a replacement set of forks than get an existing pair scanned. The idea of binning a pair of forks and adding them to landfill when they might have many years life left in them is horribly wasteful.

I presume the difference in price between a new pair vs. the cost of a scan is heavily distorted by low manufacturing costs in the Far East due to lower labour costs, possibly lower environmental standards, and high economies of scale. Nevertheless, there appears to be a big gap in the market for businesses to undertake non-destructive testing of forks and other carbon bike parts. It's a service which I would have expected at least high end bike shops to be starting to offer now, especially given the extremely high prices of the bikes at the top of many manufacturers' ranges.

In the OP's case another option might be to get a pair of custom made steel forks. They would cost more than an off the shelf pair of carbon forks, but that would be my preference for a frame requiring a fork with a 1" steerer and especially if it was a bike which meant a lot to me.

[yostumpy]

Decathlon only guarantee their carbon forks on the RC 520? for..........................................2 years!

[tim-b]

Hi

Decathlon only guarantee their carbon forks on the RC 520? for..........................................2 years!

Just to be contrary...
Trek lifetime warranty of, "Frame sets (frame and rigid fork), main frame and full suspension swing arms for the lifetime of the original owner
Bontrager wheels with carbon rims" https://www.trekbikes.com/gb/en_GB/warranty_policy/
I think that Spesh do something similar
Regards
tim-b

[tim-b]

testing costs. Unless you have something that you want to preserve then new is cheaper

snip
In the OP's case another option might be to get a pair of custom made steel forks. They would cost more than an off the shelf pair of carbon forks, but that would be my preference for a frame requiring a fork with a 1" steerer and especially if it was a bike which meant a lot to me.

"Carbon fiber is five-times stronger than steel and twice as stiff." https://www.innovativecomposite.com/what-is-carbon-fiber/
CF would do the job quite easily. I do understand that you may have other reasons for preferring steel, including that skinny, classic elegance that CF designers don't seem to use
Regards
tim-b