Bicycle Mechanics - Cosmetic or structural crack in aluminum fork

Hello,

I just purchased a old (early 90s) Cannondale Criterium 3.0 road bike from a friend. I'm a newbie at this.
I was riding it tonight but when I got home, I noticed a small crack on the fork. The fork is all alu, no carbon.
I've only had the bike a few days so I didn't notice is it's been there for a while or not.

I am wondering if the crack is only cosmetic or not. Most of the info I find online relates to carbon forks and the cracks I see are perpendicular to the fork whereas my crack is vertical (along the fork) and not exactly straight. It turns a bit.

Attached is a picture I took of the crack.

Any insight would be greatly appreciated.

Thanks !

256718

There's no way to tell from a picture. But from the shape of the scratch, it looks more like a scratch than a structural crack. I'd continue riding it, but keep a close eye on it if I suspected it was a crack. Mark the ends, or touch it up exactly up to the end, and see if it grows. If not you're good to go until it does (if ever)

Thanks FBinNY...

Just to add some information, when I drag my nail over the crack it definitely catches.
So if it's a scratch, it's certainly a deep one.

But I will for sure keep an eye on it.
I suppose the question I have now is that if it fails on me, will it be a gradual failure resulting in a crash or would it be something I would gradually see coming (crack getting larger and wider) ?

It sounds like CF just snaps when that happens but what about alu ?

There is no such thing as a "cosmetic" crack in aluminum. If it's cracked, it's structural.

But that doesn't look like any crack I've ever seen in aluminum. I strongly suspect that's just a paint scratch. If you're really worried about it, you should remove the paint from the area and take a hard look at it (I'd suggest taking it to a shop, but most shops are staffed by people who don't know the first damn thing about bicycles, so...)

Oh, and yes, aluminum "just snaps". That makes it a bad material for forks, IMO, but then I've been accused of being an old codger.

Take it to bike shop. If it is bad you can e-mail Cannondale and ask about warranty coverage or look in the yellow pages for a welder that works with thin aluminum.

scratch>stress-riser>crack> is a predictable normal chain to failure in aluminum.

if you are not a friend of an aircraft lab tester for aluminum structures,
be suspicious.

There's a big difference between a crack and a scratch, and I strongly doubt it's a crack. Scratches however vary in depth, with deeper scratches having the potential of being the seeds of a future failure.

Given that fact that it's lengthwise, rather than running across the blade, I wouldn't worry about it too much. But I can't give you any assurance since all I have is the one photo. You'll have to make your own assessment.

As to how aluminum fails, it depends of the type of aluminum and the temper. Some grades are fairly ductile, and don't fail suddenly. Others, however, can be very brittle and snap with little warning.

Nobody can ever say something is safe, there's too many possibilities. But you can have some faith in the maker to use a reasonably ductile grade of aluminum for a fork, that the scratch is lengthwise, and that there's some redundancy since it's one of two blades.

The only fork blade failure I've ever seen was in a rusted steel fork, which snapped about 6" up from the axle, and did not cause a crash. The front wheel shifted but stayed attached. Ultimately you have to make your own decision, but based on what I see in the photo, I'd ride and watch.

It doesn't look like a scratch it looks like a crack in the paint caused by an impact to the fork. If you run your fingers over both sides of the fork do you notice any difference in the shape of the tubes?

I think the only way to tell for certain if it's a crack would be to sand off the finish.

Are you sure the fork is Alum and not steel? I didn't think they made forks from aluminium. I would stick a magnet on it and see if it's steel. If it's steel I would probably leave it alone. If it's alum I would contact Cannondale and see if you can get a replacement.

Are you sure the fork is Alum and not steel? I didn't think they made forks from aluminium.

Yeah, Cannondale made some forks from aluminum in the past. My 1994 Killer V 900 came with a beefy aluminum fork Cannondale called the Pepperoni.

I would inspect it VERY closely under bright light with a magnifying glass. If it is cracked, DO NOT ride on it as failure could be total and sudden.

I also tend to agree with post # 4 about alum being used in forks ....but then I too am an old codger.

Chaotik, That looks like a deep scratch to me. I have an '89 crit bike that has worse injuries than what appears in that photo. Of course it's up to you to determine the extent of the damage. Use a sharpie to mark the upper and lower points of the scratch, ride as you normally would and check to see if the scratch ever extends beyond the marks.

Brad

Yeah, Cannondale made some forks from aluminum in the past. My 1994 Killer V 900 came with a beefy aluminum fork Cannondale called the Pepperoni.

Any my 3.0 criterium frame from 1988 or so has an aluminum fork.... with a somewhat scary gap between the crown & blade.

Any my 3.0 criterium frame from 1988 or so has an aluminum fork.... with a somewhat scary gap between the crown & blade.

Do you still ride it ?

I was informed by a neighbor that Cannondale as a lifetime warranty on their frames and forks.
Here's my issues with that though:

1- I am not the original owner but my friend is so I guess I can circumvent that one.
2- The bloody bike is like 20 years old so of course, there is no sales receipt.
3- The store where it was originally purchased is 300km from where I am. So I would have to go through another AD.

How picky is Cannondale when it comes to honoring the warranty ? I read online that they are pretty good but given the circumstances described above, am I wasting my time running around with this ?

Thanks again for all your help !

Even if there is a crack under there, it was obviously preceded by a scratch, indicating an impact. So I doubt Cannondale would offer to do anything for you. But that's just my guess based on this single photo and I'm not an expert.

I don't think Cannondale even makes a fork to fit that bike any more.

No matter- a decent replacement fork should only cost $50 or so from an LBS. You may be able to find a cheaper one used.

Edit: But I think it most likely looks like a scratch. I would ride it or get someone else's opinion who can see the fork in person.

I was informed by a neighbor that Cannondale as a lifetime warranty on their frames and forks.


If there is a problem with OEM manufacturing and/or materials. A scratch is outside of that warranty. You maybe able to get a discount on a new frameset with the trade of your frameset. Cannondale is under new ownership, I don't know what they'll do. Nashbar has some inexpensive carbon fiber forks with threaded steerers if you feel it's needed.

Brad

We need a much better picture from a proper camera, but it looks like a scratch from the fuzzy pic you've posted.