Am I the only one massively paranoid about carbon forks?

I’m definitely irrational about it… Had an old Exotic carbon mtb fork which I had utter, baseless faith in and basically just rode the bike as hard as I dared. I think Scotroutes still has that fork now? It was visibly flexy, on braking you could see it draw back like a bow but it just worked. People used to tell me off for “cheap carbon” but it was exactly the same fork as Nukeproof and White Bros sold, they just weren’t cheap.

But I replaced that with a Hylix which was a little bit lighter, and way way stiffer and I just could not trust it. Not for any reason, it just never got the benefit of the doubt.

an old Exotic carbon mtb fork which I had utter, baseless faith in and basically just rode the bike as hard as I dared. It was visibly flexy, on braking you could see it draw back like a bow but it just worked.

I was just tempted to mention mine, I used to ride it down stair sets, and noticed the same flexibility as you while braking. I used a 27.5″ A2C on my 26″ bike and a 29″ A2C on my 27.5″ bike. I had less faith in the longer fork while riding the larger wheeled bike, it just seemed that little bit more flexy (which it probably was) which was enough to trigger tiny little niggling worries from time to time.

This trials rider broke both legs of his carbon trials specific forks.

Can’t say I’m sorry I generally can’t afford carbon bike parts, really not bothered at all, and in 99% of cases I dislike the look of it anyway especially road or gravel bikes, fugly things.

Sounds like youre plenty bothered.

Friend use to ride,and Guercotti , and the fork flex on that was bonkers

I once ran into the back of a car at around 20mph on a carbon forked Bianchiroad bike. Intercostal bruising for me, the fork ran for several years more without a problem.

Carbon forks are pretty mature technology and there must be approaching a billion pairs out there.

Still have my 2001 Colnago CT-1 with carbon forks – we were out riding in the Surrey Hills descending a narrow lane with a blind bend. A car came round the bend and stopped in the middle of the lane, I went left and ran a little off-road into a bank on sand. It stopped me dead and I did a full summersault with the bike. I continued to race that bike for another 10 years, as well as many trips to the likes of Paris-Roubaix, da Ronde.

I’m still riding a pair of Pace RC31s – I like them because they’re quite compliant.

Never had a carbon fork fail on me, but have with alloy and steel.

Sounds like youre plenty bothered.

Perhaps the way I expressed it was confusing for you.

The perception is that, being brittle, carbon fibre will shatter.

Whereas a steel fork will bend.

one of the things I fail to understand is when people (marketing) talk of carbon composites.

the only extra in this equation is the resin (glue) between the carbon strands.

you’d think the manufacturers would integrate some other material to complement carbons strengths and weaknesses.

maybe a very thin layer of aluminium alloy over the fork to hold it together if there’s a fracture.

The flesh of a banana isn’t particularly strong, but combine it with the banana skin and you’ve got a sturdy combination.

so why can’t the manufacturers invest some r&d into something other than carbon and glue?

as for suspension forks and magnesium. I’ve got magnesium pedals and they’re crazy tough.

My instinct is that the safety tolerances built into suspension forks are way above anything else in cycling.

Article on Cycling Weekly about the latest Scott road bike which is stupidly light. Wall thickness of 0.6mm on the frame. I wonder what the fork is?

so why can’t the manufacturers invest some r&d into something other than carbon and glue?

Technically they do, different grades of carbon, with different properties and the weft going in different directions to provide specific strengths against loads in particular locations.

so why can’t the manufacturers invest some r&d into something other than carbon and glue?

Some carbon steerers have fiberglass in there, I have a set of Columbus Carbon fork that look like the inner section is fiberglass (ligher colour material). I believe it’s to do with preventing galvanic corrosion between the carbon and the alu compression plug. It might possibly make them a bit stronger too..

I took the suspension forks off my commuter and replaced them with some carbon ones from Exotic and rode the hell out of them for two solid years of town, summer and winter, snow, ice, salt, occasional sun, several near misses, one actual crash in Stockholm and they are fine. I think they are very overspec for the riding though (metal crown, carbon tubes), so not surprised.

My road bike has more smaller, aero profile carbon on the fork and, well, it’s had a slightly easier ride (i.e. no winter riding), but the roads have never been super-smooth and I have put a lot of miles on them. They still work.

It’ also the steerer that worries me. The number of photos I see of bikes with so many spacers above the stem that the compression plug can’t possibly be reaching the bottom of the clamp scares me.

I suspect that it’s all superstition – i reckon maufacturers build them to not break, cos otherwise they’d get sued to heck and back.

An LBS told me that carbon forks are overbuilt that they’re unlikely to fail….peace of mind

What is the most recalled product in the industry? Carbon forks. For a whole load of reasons but generally due to flaws in manufacturing that aren’t spotted and/or parts interface stress.

a couple of characteristics of aluminium (eg as used for most bars and syems)…

– no endurance limit- ie it always WILL fail under fatigue loading – the question is only ‘when’, not ‘if’.

– age hardening- aluminium gets harder (= more brittle and faster to fail suddenly once there is any cracking present) over time.

Carbon concerns tend to come from variability in manufacturing and the potential for a sudden mode of failure. Carbon parts also have flaws that can grow over time to become failure points, a sort of fatigue process.

I use an extra long compression plug.

My instinct is that the safety tolerances built into suspension forks are way above anything else in cycling.

I sent a frame and fork for testing a long time ago (CEN test, same as the current ISO test). Usually a dummy girder fork is used but I wanted to know how the whole system tested – the suspension fork stanchions broke off well before the frame test was complete.

Deda 70mm compression plug, from Amazon

(which it won’t let me link to)

Still have my 2001 Colnago CT-1 with carbon forks – we were out riding in the Surrey Hills descending a narrow lane with a blind bend. A car came round the bend and stopped in the middle of the lane, I went left and ran a little off-road into a bank on sand. It stopped me dead and I did a full summersault with the bike. I continued to race that bike for another 10 years, as well as many trips to the likes of Paris-Roubaix, da Ronde.

I’m still riding a pair of Pace RC31s – I like them because they’re quite compliant.

Never had a carbon fork fail on me, but have with alloy and steel.

2 high-end carbon forks with a very good rep. Of the billion that may be out there (I’m guessing fewer but anyway..) they’re probably in the top 1%.

I’ve had more steel forks fail on me than carbon, but I ride steel forks a lot more. The fact that one failed with a visible crack that I continued to ride for maybe 200 miles before getting that odd flat tyre feeling, and the other bent a bit and I rode out of the situation, is why I like steel forks. The idea of carbon giving way in the way it can does influence my choices tbh.

Carbon forks are pretty mature technology

I don’t agree – there have been changes in how they’re made in the last 5-10 years (no-one’s been developing much new in the last 4-5 years) and some of that was inspired by lawsuits after failures. Not all factories have followed those changes either. I’ve seen a lot of variation in production processes in factories, esp. considering the forks all look about the same once finished.

It’ also the steerer that worries me. The number of photos I see of bikes with so many spacers above the stem that the compression plug can’t possibly be reaching the bottom of the clamp scares me.

It’s only really a problem if they’re heaving on the Stem clamp bolts, but agree it’s less than ideal.

The thing that does scare me a little at the minute is the pictures I keep seeing of road and Gravel forks designed for fully internal routing. They all have an in-moulded snakey hole that goes in through the side of the steerer (normally at the the tapering section) and then pops out of the left leg for the front brake line. I can’t believe that is not introducing an inherent structural weakness mostly for the sake of aesthetics.

If it’s reassurance you seek, go watch the 3 Peaks Cyclo-Cross race, plenty of carbon forks getting absolutely hammered on the PyG descent.

If it’s reassurance you seek, go watch the 3 Peaks Cyclo-Cross race, plenty of carbon forks getting absolutely hammered on the PyG descent.

Or pretty much any of the cobbled classics. Most of the failures (of which there are very very very few) are at the bottom of a massive, multi rider pile up at 50kph, or very soon after.

Columbus SLX steel is about 0.9mm at the ends, and 0.6mm in the middle with rifle re-enforcement at the lugs – that’s from the late 80’s. It’s tin foil. Mine is still going strong at nearly 35 years old… all materials have a fail threshold.

Steel forks flex a lot fore and aft to absorb the road shock. Steel is best, followed by carbon. Alloy is terrible for fork blades.

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the forks are all scuffed at bottom of leg and chipped on the drop out

In a hard case or had a spacer installed in the dropouts…probably fine.

In a soft bike bag with no spacer/spare hub, I’d be worried that the fork legs could have been squished together when they were damaged.

Or pretty much any of the cobbled classics.

Brand new team issue bikes prepped by pro mechanics, Vs mass produced, contract manufactured forks on a 2nd or 3rd tier brand?

3 Peaks descent is a fair point but the strength of an average carbon fork isn’t in question. They can sail through ISO strength and fatigue tests. But manufacturing in volume means inconsistencies creep in and they’re hard to spot, that’s where problems arise. Never mind headsets, stem and spacers digging into the steerer.

I wouldn’t say I’m paranoid about carbon, just cautious and starting from a position that lacks trust.

I’d have thought the manufacturers would have integrated graphene into the forks…maybe wrapping a layer one molecule deep around the fork legs.

Those fork ends were the result of a head-on dead stop at 20 mph into the side of a Mercedes ML. The carbon bars snapped too, as did quite a few parts of me (15 bones).

Son1 hit a kerb with some carbon forks and alloy steerer, went over the bars and bent the fork crown but didn’t break the carbon forks. Plenty strong enough but of course they went in the bin.

Giant found me a replacement set of forks and I’ve ridden 1000s of km on the Propel and I save the nice white replacement Propel SL just for races. Carbon forks don’t worry me. After all it hold planes up in the sky.

After all it hold planes up in the sky

Bike industry carbon really isn’t aerospace grade or process level though. All I’m saying is .. carbon fibre construction varies massively. When it fails in a fork it can be very serious, it’s wise to be cautious. Rates of failure are fairly low but for the potential severity of outcome .. personally I think it’s too common, or the safe range for set up / assembly of parts onto it is too narrow for something used so widely.

Brand new team issue bikes prepped by pro mechanics, Vs mass produced, contract manufactured forks on a 2nd or 3rd tier brand?

Well, yes. You want to pay less for stuff, it probably won’t be as good.

But if you buy top end stuff, you’ll be getting the same stuff as the pros.

^ you may well do, still, big brands have recalled forks for production and parts interface issues. But rarely* and I agree, buy from a brand like Giant and the risk should be low. But there’s riders buying cheap dc2 versions of those reputable products thinking it’s all much of a muchness, safe at least, while they vary more than we might realise? That’s my only real point here – the variability in construction or part fitting margin of error creates an amount of risk. Buy good kit and be careful with it, or buy cheaper kit and be cautious about the safety of that one item. (and there are cheap and good quality carbon products out there, making this more difficult to navigate as a buyer).

*more often than I think should happen based on the size of the industry and the possible outcomes, but that’s just my opinion

In my world it’s ‘QC’ and ‘QA’ (simplified)..

QC (controls) is the input side, materials and processes.

QA (Assurance) is inspection and testing (destructive and non).

The more you do of either the more you add cost.

The thing to remember is that there is no 100% set of measures that can fully prevent a faulty product reaching a punter, all it ever does is reduced the probabilities of failure. 

You can say exactly the same about steel forks as you’re writing for cheap versus expensive carbon.  One hokey weld …..

Thinking about I’m ok with carbon forks, and steel, but I really don’t like Al or Ti.  But how often do you see those?

You can say exactly the same about steel forks as you’re writing for cheap versus expensive carbon.  One hokey weld …..

It is possible to have a look at the welds on a steel bike and get a pretty good idea of their quality though. If they’re full of holes and big uneven lumps of steel then they’re probably no good. With carbon it’s hard to know what’s going on in the layup.

I’m pretty happy with carbon forks and more worried about things like eyelets for bottle cages coming unbonded than the whole fork failing during normal use.

When I think about the stress loads that a high performance carbon dinghy mast goes through and some of the loadings around rigging mounting points the loadings on a bike fork (or frame) must pale into insignificance (I tell myself!).

So what are the failure rates of carbon forks…..what is the evidence so we can be more/less worried that we currently are…..

Anecdotally – I’ve been riding rigid MTBs on carbon forks (Pace, Niner, Whisky, Exotic) across the Fells, Peaks, Pennines, Valleys and Quantocks for 20y and have never given it a second thought and never have any of them given me any reason to.  I’ve also ridden plenty of carbon suspension, road and gravel forks for many 10s of thousands of km with ZERO issues.

It’s the carbon steerer that frightens me. Did I over tighten the plug?

Is the plug long enough, did you over tighten the brake/brifter levers, is that torque wrench calibrated correctly did you set it to the the right nm and take into account any carbon paste  🙂

So many worries you can have with carbon but tbh metal forks and bars also fail, everything’s fine until it isn’t 🙂