"Scratch" on steel fork blade; cause for concern?

[Hat]

Noticed this on the inside of one of the fork blades as I was sanding away - about 2 inches long and can be barely felt with a fingernail. Should I be concerned or just forget and paint?

http://i.imgur.com/2ifiAkml.jpg

http://i.imgur.com/uOZ2gpUl.jpg

[Ken Robb]

If it's just a scratch with a solid bottom no problem but if it's a crack it's scrap metal. I can't imagine how a long narrow piece of steel like that could crack longitudinally though.

[rustychisel]

it may be the camera, but the way that 'steps' a third of the way along, and the associated parallel marks would make me very nervous indeed. Be extremely prudent.

[RonW87]

Looks to me like a crack, not a scratch.

[pbarry]

it may be the camera, but the way that 'steps' a third of the way along, and the associated parallel marks would make me very nervous indeed. Be extremely prudent.

+1

From here, and zooming in, it appears the fork suffered some serious trauma, more than a scratch--never seen this before. In the last image, the fourth horizontal mark from the bottom is especially worrisome..

If it were mine, I'd replace it

[oldpotatoe]

Looks to me like a crack, not a scratch.

Me too...I'd have a frame builder look at it.

[staggerwing]

Photos suggest nothing good. However, before making a rash decision, what was the condition of the paint before you started sanding and how old is the fork?

In other words, do the discolorations correspond to similar scratches in the paint? If old enough, and ignored long enough, it is entirely conceivable that the paint acted as a mask for the corrosive activity. Still, if it doesn't readily hand sand away without too much additional work, then a new fork might be in order.

[Steve in SLO]

Remember: a steel fork is cheap, dental work is not.

[Hat]

Photos suggest nothing good. However, before making a rash decision, what was the condition of the paint before you started sanding and how old is the fork?

In other words, do the discolorations correspond to similar scratches in the paint? If old enough, and ignored long enough, it is entirely conceivable that the paint acted as a mask for the corrosive activity. Still, if it doesn't readily hand sand away without too much additional work, then a new fork might be in order.

I would guess the fork is from around 96-97. The paint was missing from the scratches, almost looked like termite tracks in wood.

The fork is off a Mikkelsen frame that ended up cracking near the bb due to what I suspect to be internal rust. The fork however shows no obvious signs of corrosion.

[jtakeda]

If the frame is toasted I wouldn't put a ton of faith in the fork.

It looks cracked to me.

[Louis]

That would be a strange place for a fork blade to fail due to regular ol' riding loads. I'd keep sanding to see how much deeper it goes, but I don't think I'd ever ride it again.

[Hat]

I'm leaning towards toss as well. Does anyone happen to have a 1" steel fork with a very long steerer? About 260mm if threaded or 300mm+ if threadless.

[Louis]

I do but it's busted.

If you buy one used be sure to be absolutely certain that it hasn't been in any head-on accidents.

[staggerwing]

I would guess the fork is from around 96-97. The paint was missing from the scratches, almost looked like termite tracks in wood.

The fork is off a Mikkelsen frame that ended up cracking near the bb due to what I suspect to be internal rust. The fork however shows no obvious signs of corrosion.

Based on that info, the paint did act as a mask for the corrosive activity. I would give that zone about 10 minutes of hand sanding with some 180 grit silicon carbide (black, wet-or-dry) sandpaper backed with rubber block, using soapy water as lube. If that doesn't find bottom, it is time to move on.

[David Kirk]

It looks to me like a material defect stemming from when the fork blade was originally drawn. It's rare but one can sometimes see gouges from galling where the blade material 'grabbed' the mandrel that run along the tube. I haven't seen this very often over the years but it's not unheard of........when seen these blades go into the 'warrantee' box for replacement.

My very rough guess is that it has always been more or less like you see it but that it was filled with putty when originally painted (unacceptable) and may speak to the idea that the fork is as safe now as it ever was. All that said it's time to make a lamp out of this thing and find a new fork IMO.

dave

[cbresciani]

The part that makes me think it's a crack and not a scratch is the parallel scratch or crack that is near the top of the fork where the crack\scratch starts. This looks like metal fatigue to me.

[pbarry]

It looks to me like a material defect stemming from when the fork blade was originally drawn. It's rare but one can sometimes see gouges from galling where the blade material 'grabbed' the mandrel that run along the tube. I haven't seen this very often over the years but it's not unheard of........when seen these blades go into the 'warrantee' box for replacement.

My very rough guess is that it has always been more or less like you see it but that it was filled with putty when originally painted (unacceptable) and may speak to the idea that the fork is as safe now as it ever was. All that said it's time to make a lamp out of this thing and find a new fork IMO.

dave

Dave, your comments on bike building/construction/design are well respected and always appreciated here. Thank you.

I don't think you've ever met Bernie, you'd remember him ;). One of the most efficient frame builders ever, imo. In his prime, 6 hours total, from the start of a build to finish paint was the norm. Small one man shop, design, build, paint. He abhors filler and keeps cut-aways of head tubes from major brands hat he's repaired, showing major voids in brazing. Also, a consummate fillet brazer.

I agree the first three horizontal marks in the last image may have been from biting of the swaging machine, but I've been in Bernie's shop while he was working, and seriously doubt he would have used a "warranty" blade in the first place. [Full disclosure, I taught him how to build with Ti after I left Merlin, and ended up learning more from him about steel.]

The large vertical crack and parallel marks would not have been caused by swaging, (nor filled by BM, imo). Patina remaining in the valley after sanding the paint disproves your theory: If the fork had been media blasted, (and the mark(s) were clean), then there might be more questions.

Without seeing the condition of the paint before stripping, and more detailed images of the frame, we are all working on conjecture here.

Cheers

[David Kirk]

....................

Without seeing the condition of the paint before stripping, and more detailed images of the frame, we are all working on conjecture here.

Cheers

Good Morning -

I agree - it is all conjecture to a degree and we will never really know what caused the issues in that fork blade. I will say that I've never seen a blade crack in a long vertical line like that......plenty of cracks running across the blade but never once that I recall running the long way.

I have seen plenty of blades (and other swaged parts like seat stays and chain stays) with longitudinal drag lines resulting from the swaging process. I've also seen blades that look fine before being curved for rake but once undergoing the stress of raking show longitudinal marks like shown in this fork.

But like you said - it's near impossible to know with any certainty what happened to this fork blade and when. I do know that I wouldn't want a friend or loved one to ride it just out of an abundance of caution.........it's one thing when a chainstay fails and an altogether different thing when a blade fails.

Thanks for your thoughts.

dave

[Hat]

Here's the best pic I have of the fork prior to sanding and one showing the overall state of the frame

http://i.imgur.com/umVfvuD.jpg

http://i.imgur.com/916jQYb.jpg

[malcolm]

That is a beautiful and well used frame. You or someone got their moneys worth. Retire it and the fork.

[Admiral Ackbar]

what?? that frame is in fine condition. scratches and paint chips are no reason to retire \a frame

[Ken Robb]

I have to say that I have never seen a nice frame as beat up as this one. My 1989 MB-3 mtn. bike looks better and we used to stack 3 bikes on top of each other in the back of a truck to get to the trail heads.

[Vientomas]

That's just a little "shop wear".

[malcolm]

what?? that frame is in fine condition. scratches and paint chips are no reason to retire \a frame

Not because of the frame but the fork and I personally wouldn't spend the money on a new one, unless I had it laying around. For me time to move on.

[Hat]

The frame ended up cracking after a couple months of use (since acquisition).

http://forums.thepaceline.net/showthread.php?p=1591217

[elong8]

Just a scratch?