Aahzz

OK, I tried to search, but couldn't find anything related to just a fork...I'm wanting a bike with disc brakes. My current ride is a Trek FX2, which has held up great for 1400 miles so far. I'm a larger clyde at 370, working hard to get that down, so hopefully it won't be long now, though now that I'm over 50 and on insulin the weight loss is more of a struggle than it's ever been - still, I'm determined. Going full-bore Keto on Monday . To get to the point, I adore my FX2, and I could buy an FX2 Disc and probably be happy...but am also looking at the FX3, for the better components, wheels, etc...but the carbon fork worries me. Both the 2 and 3 are officially rated for 300 pounds, but I know they're overbuilt and the 2 seems to be doing a great job of holding me so far...anyway I'm rambling. Anyone in my weight class riding a carbon fork? Thoughts?

ColonelSanders

It depends on how well built the fork is I guess.


I'm over 400lbs and the carbon fork on my Giant Toughroad has performed very admirably and given me no cause for concern.

Aahzz

Thanks, that helps. I needed to hear some experience from a larger Clyde. So many of the posts I found were along the lines of "I'm 220 pounds and worried, but they're fine" - good gods, I hope to be 220, and wouldn't be even slightly worried .

zjrog

I just picked up a zero miles 2006 Cannondale CAAD8 frame with a Slice Premium carbon fork. I've been leery of carbon due to my weight. Which a year ago was 378. I am currently 266. The CAAD8 is a reward for me when I am under 240. I had Gastric Sleeve surgery. I had too many problems rising and my options were few... It's been a real interesting journey. And I have no idea where it's going now... But I had to start. I hope to never worry about that carbon fork.

sdmc530

I was 336lbs a few years ago when i got into cycling and started riding a cx bike with a full carbon fork and never had an issue. I don’t know what the ceiling of weight on forks though.

i think though under 400 would be ok. They test frame sets at very high weights. Like cannondale tests sets at 1500lbs

fietsbob

Some are made for tandems..

wsteve464

Below is a link to a Zinn article about carbon forks with a discussion from True Temper about how they test their carbon forks.

https://www.velonews.com/2002/12/bik...n-forks-2_3270

Quote from the article and it looks like you will be ok as long as you have a name brand fork.

True Temper’s own test is also used on every new model and in routine quality checks. Our test is a ramped load, meaning the load is increased periodically until failure occurs. Starting at 180lbs, the load is increased 45 lbs. every 5000 cycles. Every fork will eventually break. Strong forks will last more than 10,000 cycles with a load of 270 lb. But our minimum standard begins at over 15,000 at 315 lbs. for road forks and 18,000 for cross forks and tandem. But our production forks are stronger than that, often going into the 20-25K range and beyond at loads 0f 360-405 lbs.

Further down the article the different manuf chime in about weight limit, basically there is none.

tallbikeman

I've read that the carbon steerer tube must be treated with care when tightening down the stem clamp. I've heard of damage to the carbon steerer tubes due to overtightening the stem clamp. The steer tube manufacturers torque ratings for the stem clamp bolts must be adhered to so that damage does not occur. Generally not mentioned in the bicycle press is several ongoing lawsuits in USA and Australia concerning carbon bicycle frames and forks that failed right out of the box and hurt or killed people. I suspect that current testing of every fork and frame coming off the manufacturers line may not be enough to stop these type of events from happening. If the lawsuits prevail I expect that carbon fiber frame and fork testing will get much more rigorous and would look something like Aerospace testing of flight components.

sdmc530

If you own any carbon parts on your bike that are tightened you better be using a torque wrench! Mfg's have the specs printed on most parts for this reason.

wsteve464

https://www.outsideonline.com/231181...dents-lawsuits

From reviewing this article it appears older carbon frames may have issues occasionally and the broken forks appear to be Chinese and have not undergone testing as there are no standards in China and you know E-bay doesn't care. They did not mention a right out of the box failure.


From the article:

It’s important to note that some of the experts on carbon fiber-related accidents I spoke with haven’t concluded that the material is patently unsafe. Instead, they say the consequences of shoddy manufacturing and wear and tear underscore the importance of buying from a reputable manufacturer and assuring the bike is inspected regularly by someone trained to maintain carbon components. Even after the lawsuits he’s seen, attorney James Reed, the New York Bike Law representative, still rides two carbon-fiber bikes, a Trek Madone road bike and a Giant mountain bike.

tallbikeman

I know a lot of us have friends that own or work in bicycle shops. At my size I have been consistently warned away from both aluminum and carbon fiber bicycles. The friends I know all said the same thing. They break too often. I have thus stayed with steel which is not as strong as carbon and much heavier, but generally has a gentler failure mode. Steel bicycle components fail too, but I believe at a much lower rate that the aluminum/carbon bicycles. The way steel is made into piping gets rid of air pockets and reliably homogenizes the material into just steel and no voids. Carbon fiber is basically cast and this has a much higher rate of getting air pockets and is a hard problem to deal with. Ultrasonic testing can cull out the bad carbon components but I'm not sure manufacturers are doing this on new components. It is costly to perform the tests. I believe carbon fiber is in its infancy for bicycle manufacturing and if it persists into the future these problems will be solved. Carbon fiber is a wonderful material. Wsteve464's link to the Linn article is eye opening. The carbon fork manufacturer Deda states that: From Deda:
Carbon lasts longer than metal.Only love is stronger than carbon.Bonding is a different story.I believe that a good glue (epoxy) can last for 2000 hours of work, or about 800 days, not in continuous daylight, and below 35 Celsius.Whenever a carbon “part” has crashed, even if you cannot see a failure, if there is any reasonable doubt about having surpassed the elongation limit, the part must be replaced.
–Fulvio Acquati
So when talking about carbon fiber forks we are talking about two materials if not more involved in the manufacture of the fork. As Mr. Acquati points out the epoxy resin has a much more limited strength and longevity than carbon fiber. I've used a lot of epoxy resin and it has to be protected from the sun. It is not an especially hard material and is easily dented, cut or otherwise defaced on its own. This manufacturer wants a limit on the amount of time spent working before they want their product replaced. I believe this all fits into the early days narrative for carbon fiber. This will probably get much better as time goes on. As of now there is still a whiff of we are the guinea pigs in the carbon fiber experiment. There is very little transparency in the bicycle business so it is hard to get a handle on failure rates for any material. Steel has a long history of successful bicycles and is very well understood. Carbon is still being developed. Good luck with your carbon fiber components.

sdmc530

After reading the article and the opinions of the mfg I have more faith now in carbon companies than ever even as a Clydesdale. Look, Deda, Reynolds and Easton are pretty confident in their products being safe and they hold all the liability I am feeling pretty safe too.

I think if you buy a name brand better quality component I feel you will have very VEY limited issues founded.

Wilfred Laurier

The people giving you this advice are ignorant. Modern aluminum frames fail less frequently than steel frames from BITD. I am your size (used to be bigger) and have had several steel frames fail, but not aluminum, which is my preferred material now. I saw on your profile that you have old non-super-lightweight steel bikes, which may last a long time. The argument that 'steel is better for heavy riders' ignore the spectrum of quality and design that can make a material suitable or unsuitable.

ahultin

I am not quite as heavy as the OP and have first hand experience reaching the fatigue limit on modern aluminium frames. The first was a Fuji roubaix, aluminium frame with carbon fork and carb stays, which failed at the aluminium dropout at 12,183 miles . The second was a cannondale disc fork which failed just above the disc brake mount at 7,982 miles. While I initially shied away from carbon fiber, it has proven to be the superior material

ColonelSanders

What was the Cannondale disc fork made of?

ahultin

Aluminium , it was their "fatty" disc fork

Wilfred Laurier

I have had similar failures, but funnily enough only on steel frames.

I agree that, if made properly, carbon is the superior platform for making frames and forks.

tallbikeman

All this talk about this or that material being better or worse is rather incomplete at this time because failure rates for all methods of bicycle frame, fork, and component failures are not readily available anywhere that I have searched. There is quite a bit of suing going on right now concerning carbon frame and fork failures that injured or killed people. The major bicycle manufacturers have shielded themselves from being sued through all kinds of proxy or subsidiary corporations that have left consumers in many nations no recourse for poor or hurtful bicycles. This is finally being adjudicated and the legal systems in a couple of countries are forcing a public reckoning concerning manufacturing/engineering of bicycles. I don't have to go far in these forums to find people talking about all kinds of broken aluminum and carbon components. However steel also breaks but steel is not being used by the vast majority of competitive cyclists any more so breakage rates are probably very low. I believe competitive cyclists are the main users of high end carbon/aluminum road and mountain bicycles. By competitive I mean racing in organized races or riding in a racing manner with other fit and competitive people. A lot of low end aluminum and steel bicycles are sold at the Target/Walmart's in our country and I see them in daily use. I don't know how well they hold up. Hard to get hard data about this. I've come to believe that in the real world bicycles made of steel are hardy survivors of falling down, fell over and hit the concrete step, crashed and rode bicycle away types of incidents. Carbon and modern aluminum bicycle materials are much superior to steel in stress tests yet appear to have a harder time surviving the real world of hard knocks. I'd just love to see honest bicycle industry statistics on how these various materials hold up out in "real" life. I'm not pro carbon or aluminum or steel or bamboo or any other material. I just want honest objective quantification of what is available and how well it holds up with use.