SortaGrey

Searching the archives is problematic... mostly salad and recreational posting. Hence I'll summarize what I learned/read.. to date.

After hashing this thread out.. what I meant to focus on is the FAILURE MODES of different fork materials. Common internet platter is thrown around like male cow dung on the subject.. to date I have NOT found a good read on this.

When bike people of experience such as FBinNY question the durability of carbon steer tubes.. that to me is of note. This matches concerns I've found with other bike repair/avid riders of long experience.

Reason for my interest in this subject was to talk myself into a carbon fork with alloy steer... from a brand via a name discount bike online store. I could find no record online of anyone having performance issues with them. Contacting another online source raised a red flag to my way of thinking-- Warranty issues.. details of which were not given when requested. From that.. I take it to mean if one has issues your then attempting to deal with someone who fabricated said fork from over the pond. Good luck there.. so it seems.

I'd offer even going out for a bike ride is likely more dangerous than mounting almost all of the carbon forks (w steer steer tubes) manufactured. Yet the failure mode of carbon forks most often gives no warning.. your down. Yes other fork materials fail.. but the postings of carbon failures is so numerous around the net. Steel forks for instance have been around for a century.. on millions of bikes.. those failures are seldom found looking over the net. Just seems to me.. carbon failure is percentage wise too high.. for a 235 lb rider like myself. Bike riding means risk of injury.. adding a carbon fork is just one variable I'll avoid.

Marketing.. is today's world. The hype and nonsense of websites.. saying allot.. often meaning little. Another item is the testing of components with said manufacturer paying for.. or doing that testing. That testing is nearly meaningless for me. I've no doubt some are interested in brand promotion.. the integrity of their name and products. Yet per unit cost.. the bottom line rules.

https://www.pardo.net/bike/pic/fail-001/FAIL-164.html

bradtx

SortaGrey, I think you'll recieve much the same type of opinion as in your previous fork material thread. Again, regardless of fork/steerer material there have been failures across the board.

Brad

SortaGrey

Brad my idea was a discussion more in-depth on how to sort the merits of brand names... aftermarket forks.. some idea of expected failure rates. Differences in carbons etc. Just looking to dig a mite deeper.. from knowledgeable experienced riders.

DOS

I have 3 bikes, two with carbon forks with alloy steerer (why does bike industry say "alloy", doesnt that just mean aluminum of some sort?), and one 80s schwinn with steel fork and steerer. I have never given failure much thought. One of my bikes is a 9 year old cannondale CAAD7 with the slice carbon fork that came with the bike. Their focus now on carbon bikes notwithstanding, I think it fair to say that C'dale can be considered a gold standard when it comes to aluminum so I am inclined toward confidence in the steerer that I have. The other fork is a Sette carbon fork I bought off pricepoint to replace a steel fork I had destroyed (through no fault of the fork or its manufacturer). I have no clue who made the fork or steerer so I suppose that's a risk but its served me well for 6 years of regular commuting so I have no complaints (for three of those years I weighed between 235-245 before I lost a bunch of weight).

I haven't done alot of research on who is testing what, but I know alot of testing is done on tires (rolling resistance, etc) so I infer that bike industry does a fair bit of testing to improve performance without sacrificing durability across the board. Here is one link to a velonews q&a with Lennard Zinn wherein a bunch of manufacturers provide comment on their standards. https://velonews.competitor.com/2002/...n-forks-2_3270.

As for steel fork suppliers, if I were in the market, I'd probably start with some of the boutique online providers specializing in steel frames-- e.g. Surly, Salsa, Soma. These are not custom shops (frames made overseas) but they have reputation for quality at affordable price, and they use quality steel -- high end Tange and Reynolds mainly (I have Soma bike with my Sette carbon fork).

But when push comes to shove, there are no guarantees in life. Companies known for quality on occasion produce a lemon and when buying after market parts you can never eliminate all the quality unknowns. But I am more likely to get hit by a car while out for a ride than I am to suffer a sudden fork failure (in 13 years of commuting I have been hit 4x but never suffered fork failure). In both cases, I take what precautions I can and then don't worry about it.

Airburst

An alloy is basically a mixture of two or more metals. In the bike industry, "alloy" tends to be used to describe parts made from an alloy that consists mainly of aluminium (i.e. "aluminium alloys"), despite the fact that a lot of steel bike parts are made from alloy steels, and quite a lot of titanium parts are made from titanium alloys.

HillRider

Your fixation on fork failures is interesting. Do you drive a car? Have you ever experienced a front wheel bearing or steering linkage failure? These can and do lead to complete loss of control and almost always cause a crash but you still drive 60+ MPH for thousands and thousands of miles and neve give it a thought, event though these failures can happen. It's just that they are truly rare events as are fork failures from reputable makers.

As to "Gold Standard" components, I think the big name manufacturers are far more likely to do adequate testing and insist on (and inspect) proper QC procedures from their in-house plants or outside suppliers. They have a reputation to maintain and much more financial liability than a garage operation in Asia.

Cannondale, Trek, Specialized, Surly (a division of QBP), Easton, Fuji, Bontrager (aka Trek), etc are all reliable and careful companies. That said, anyone can and will make a defective part on occasion. It's just far less likely from one of the well-known companies.

SortaGrey

Fixation? Not so.. but trying to get more information... etc than the norm. What is wrong with an in-depth search for more info? Nothing.

Hard to find objective data on the net.... or anywhere for that matter.

As always.. the some fail to grasp the situation.. or what is being asked. Glossing over with an opine is not the same as looking for knowledge.

Tell the people injured by fork failures their 'rare'. Does it matter ...then? Obviously not. Nothing between a rider's person and the road when a fork gives way... somewhat different accident event.

UnsafeAlpine

I've ridden on a Nashbar carbon fork and an Easton aftermarket fork. Both held up fine. I'm now running a Salsa steel fork on my touring bike and a Salsa in-house full carbon fork on my 'cross bike. I trusted the Nashbar fork the least and used it for a year before I could replace the entire bike.

The gold standard for forks is name. Any of the major fork manufacturers are going to have a better quality check than the online cheap stuff. In general, these forks are carried by reputable LBS's because the LBS is also lending it's name to the quality of the products they sell and certainly have more to lose than a knock-off Chinese company.

DOS

[QUOTE
Hard to find objective data on the net.... or anywhere for that matter.
[/QUOTE]

The reference to ATM in the Zinn Q&A I posted got me curious. One search came up with this so I guess if you want to do more research, you could spend some money on the test reqs.

https://www.astm.org/Standards/F2273.htm

I also found some references to testing labs like this https://www.microbac.com/testing-serv...onent-testing/, and testing papers like this one https://www.oemcarbon.com/2012/08/fat...bicycle-forks/

and this one: https://www.wpi.edu/Pubs/E-project/Av...cycle_Fork.pdf.

So if you are inclined toward caution, I infer from fact that I found these various things among the top results with one google search, that there are both bike industry-affiliated and independent resources available to get some of the data you seek.

HillRider

OK, while you are at it get the data on stem and handlebar failures. These have the same consequences as a fork failure.

I once had the handlebar clamp bolt on a stem break and I was on the ground instantly. Fortunately it was at a walking pace as I had left a traffic light so my injuries were very minor but, at speed, it would have been far different.

DOS

Yeah, lots can go wrong on a bike and if its front end, bad things happen. Hell, even a bad blow out of front tire can be catastrophic. Why do we even leave the house? . For me, the only thing thats ever snapped on my bikes was a steel chain stay. That made me stop but I was not in danger of calamity.

rebel1916

Methinks you have an agenda...Also, you have some pretty serious misconceptions regarding QC in the modern era.

fietsbob

Are you willing to pony up the cash to have a custom made fork made out of light,
resilient, but expensive, Steel parts?

then you and a custom framebuilder of your choice can begin your discussion..



Most of the Business is in Price Conscious bikes , but they want the latest stuff..

so the companies contract out to Asian companies the make the parts in volume .
maybe 1 in a 1000has a defect, so then the recalls take back the other 999
to be on the liability safe side.

3alarmer 

.........but forks of various designs, materials, and manufacturer get recalled on a pretty regular basis.

https://www.google.com/search?q=bicy...hrome&ie=UTF-8

This has been the case going back to the first alloy fork designs.

But it is quite possible that it is more related to the greater emphasis on
consumer safety and recalls in the era of alloy, carbon, and suspension
fork designs than to the materials involved..

In short, I don't know of any reliable data.

https://www.cervelo.com/en/support/recalls.html
https://velonews.competitor.com/2011/...reakage_161173
https://thebicycleplanet.com/articles...forks-pg56.htm
https://www.cpsc.gov/cpscpub/prerel/prhtml12/12149.html
https://www.cpsc.gov/cpscpub/prerel/prhtml12/12281.html

SortaGrey

"Methinks you have an agenda...Also, you have some pretty serious misconceptions regarding QC in the modern era."

That.. first part is just nonsense. Just an honest inquiry. What is wrong with asking a few quesitons? Does everyone around here work for the bike industry..... Ask a few hard questions and the riot squad starts in.

My views of QC in this era are right on. You have another view.. fine. We'll agree to disagree on that pt.

Why not.. rather.. just discuss the tech merits of forks flavors? THAT..was MY intent.

I fail to understand.. how a carbon fork just icicles. I've little practical knowledge of them.

Airburst

They don't actually fail like an icicle - ice is brittle and shatters by fast crack growth, carbon-fibre reinforced plastics (to give their full name) are fairly resistant to crack growth. The issue with carbon forks is that a metal part will likely give some indication that it's going to fail, often in the form of a visible crack or some sort of ductile deformation, while potential failures in carbon components aren't always as easy to spot.

fietsbob

note the current trend is to use the design flexibility of CF composites , and increase the diameter of the lower race
to something like an inch and a half , and retain the 1 1/8th up top.

Dont like chasing the high tech latest thing trend ? lots of 1" threaded steel fork bikes are still on the road.

perhaps someone makes a 1.125" fork steerer that is Butted at the bottom, like the steel 1" steerer's are.

wphamilton

A friend of mine tested fatigue failure of carbon composite materials for aircraft design and came up with 400,000 flexes before failure, and that number seemed similar to what I've seen for bicycle carbon fiber. Fatigue limit for aluminum is on the order of ten million cyclic stresses if I recall correctly.

That's all more vague than I'm comfortable with, and it's not really a hard limit of stresses before failure but more like a probability of failure that increases as the number of cyclic stresses increase. Does anyone know of more specific and reliable numbers for fatigue failure, comparing carbon fiber, aluminum and steel? You won't hit the limit with aluminum with the stresses from normal riding but the 400,000 for carbon fiber seems approachable given enough time.

rebel1916

Where did he publish his findings?

FBinNY 

Like SortaGrey, I'm not a fan of carbon steerers (carbon blades are OK though). My reasoning is similar to his also. When considering the safety of anything I use an analysis that factors both the likelihood and consequences of failure. Where the consequences aren't likely to be serious, I'll accept a high rate of failure, however as the consequences become more severe I try to bring the likelihood to as close to zero as possible.

Given that a fork failure at the base of the steerer is probably the most catastrophic of all possible structure falures on a bike, I stay with the proven reliability of butted steel steerers for personal use.

That said, not all carbon fork failures are the same. Some manufacturers employ a safety net approach, usually using a few layers of fiberglass weave at the crown. This has enough flex to tolerate the bending that shatters carbon fiber and can hold the fork together a while. It's an old tried and proven approach going back to the use of wooden dowels in the bases of steel steerers.

I suspect that the biggest issue with carbon forks is that of sourcing and quality control. While I trust that the reputable firms have decent quality control standards, and choose and monitor their vendors carefully, I'm not sure this applies to all, and especially unknown suppliers. Then there's also the lack of long term history about product life under various conditions. If a given fork is OK for 50,000 miles of road use, how many of those can be on Pave?, How hard an impact from a deep pothole, unseen bump, or light impact can the fork tolerate?, if within the limit, how many severe jolts is too many?

When I ride, and descend at 40+ mph, I don't want to be thinking about my equipment. I ride for pleasure and trust in my equipment ranks much higher than any possible weight savings ever could.

pierce

pure aluminum is butter soft in thin walls.

the auto industry liked to call aluminum alloy wheels "mags" because many of them contained some small percentage of magnesium, but in fact virtually all of them are mostly aluminum.

here's a typical aluminum alloy, 6061...

• Silicon minimum 0.4%, maximum 0.8% by weight
• Iron no minimum, maximum 0.7%
• Copper minimum 0.15%, maximum 0.40%
• Manganese no minimum, maximum 0.15%
• Magnesium minimum 0.8%, maximum 1.2%
• Chromium minimum 0.04%, maximum 0.35%
• Zinc no minimum, maximum 0.25%
• Titanium no minimum, maximum 0.15%
• Other elements no more than 0.05% each, 0.15% total
• Remainder Aluminium (95.85%–98.56%)

so, all the non-aluminum stuff in it combined is less than 5%, maybe even less than 1.5%

DOS

Right, for steel alloys the say "cromo" or just use the branding (Reynolds 853 or whatever) but for alu sometimes they'll use the specific alloy (6061, 7075, etc) but more often they say alloy (ally nipples, alloy steerer, alloy seatpost) mostly to generally distinguish from either brass (nipples) or carbon. Never (or at least rarely) is a bike component made from a steel alloy referred to generically as alloy.

Airburst

To further complicate things, british convention is to call the damn things "alloys", as in "watch out, you're gonna kerb the alloys!"

Slightly ironically, brass nipples could be referred to as "alloy" as well, brass being an alloy.

FBinNY 

There's a big difference between a handlebar, stem or top of steerer failure vs. a steerer/crown failure. The latter is an instant faceplant, as the front wheel falls away and the head goes to ground. The first may cause a crash, but not of the same kind and the consequences tend to be far less critical.

UnsafeAlpine

For comparison, I'd just like to say Trek STP400.