Is this fork toast?
 

I'm in the process of stripping and rebuilding my 1996 Bianchi Reparto Corse cyclocross bike. Lugged steel, Dedacciai zero uno tubing. I took the fork off and noticed some cracks in the paint at least on the underside of the crown roughly around where the steerer tube circumference would be. See pic. Is this a sign of damage or nothing to worry about? I can take it by a frame builder but I thought I'd post it here too. Thanks - Colin

Could be just cracked paint. Just take all the paint off so you can see what you have. If you or a friend have a sand/bead blaster use that if not sand paper or stripper and time will work. You really need to see what is under the paint for a correct answer. Roger

I'd have to see it closer, but it looks like the braze didn't completely fill the steerer/crown joint. Water will or did wick into the gao and start a corrosion process. It's not a good scenario, but the fork may still be sound if the bulk of the joint is OK.

Not seeing it, closely I can't give you a solid opinion, but based on the photo, I'd take steps to stop the rust process, and seal/fill the gaps and keep riding. But as a backup safety measure I'd keep a stainless 6mm bolt in the brake hole full time. That will keep the crown and steerer together if the braze fails.

The bolt will keep the steerer from separating from the crown if the joint fails but it won't help if those are indeed cracks and they propagate through the crown itself and one side of the crown breaks off. I agree that removing the paint carefully from the suspect area and inspecting the condition of the metal underneath is an essential diagnostic technique.

I agree that there's a risk of crack propagation into the crown itself, which is why I tried to make sure that the OP understood, that a detailed examination needed to be made before any real opinion could be formed.

The OP mentioned having a framebuilder take a look, and that's the best course of action.

Yeah. I don't like the looks of those four cracks radiating from the steerer.

The Brazing flow was not drawn out to the lowest part of the joint,
Not unusual for Mass produced Bikes ..
the filler braze wire was probably applied from the crown race seat of the fork crown
while the whole thing was Red-Orange Hot ..

it just may not have flowed fully down to the lowest point,
it seems to have filled to the front and back of the crown-steerer interface.

but it's just a picture.. and remote suppositions.

Strip off the paint, if it looks OK , do a repaint.

Tough to say from the pic and with the paint, but the fork crown is certainly one piece with the steerer and legs brazed to it. If those four lines radiating from the bottom of the steerer extend into the metal under the paint, they are not unfilled joints but cracks in the crown itself.

It looks crashed to me.

Do not use a mechanical stripping method to remove the paint, especially a wire wheel, it can blend the edges of small cracks and you won't be able to see them. Use a chemical stripper, in many cases it may actually highlight the cracks. I did weld inspection in a "former life" and had to do a lot of failure analysis.

A Magnaflux or Magnaglo inspection would be ideal but would probably cost more than a replacement fork.

A quick and dirty method is to thoroughly clean the suspect area then soak it with penetrating oil overnight. Clean the surface around the suspected cracks with alcohol and wait a few minutes. The oil will wick out of any cavities such as a crack and show up on the clean surface. It's not 100% effective for very fine cracks but it works pretty well.

I wonder if there's some sort of acid or something that could be used to clean the corrosion out of the cracks and gaps so it could be brazed up?

We need a like button.

Muriatic acid. Available almost everywhere, great for rust removal and of course pool cleaning.

It has many uses besides metal prep and concrete cleaning as well. I had a trash tree that popped up between my gas meter and foundation before I bought my house that just kept coming back no matter how close to the ground I cut it off and because of the location I couldn't get to it to dig it up. I tried Roundup, etc. but it just kept coming back year after year. Finally out of desperation I doused it with muriatic acid. It stopped growing and eventually the stump rotted off.

Neato, thanks for the tip.

If the crown itself is cracked, I'd be reluctant to trust brazing to fix it.

I'll second that. TIG welding, yes, but unless you have buddies who are GOOD TIG welders or can do it yourself it would be cheaper and safer to just replace the fork and hang that one up as a "trophy".

Plain and simple; it's landfill. If you take the paint off, you will find more damage. bk

Perhaps I should explain. From a riders perspective, the fork/steerer joint is a critical safety item. To a competent mechanic, it's a critical liability problem. He's thinking; this needs to be completely cleaned out and welded. All the braze has to go. The steerer tube may also have to be replaced. Then there is fixing all the cracks in the fork top. Some of those may need reinforcing. And his insurance company will still be ticked off if they knew he made a repair of this sort.

OTOH, selling you a new fork gets rid of these problems and isn't subject to underestimating the work that will be required. It will save you money and he'll make some money. Bottom line; the lawyers have determined that fixing your fork is a real bad idea. That doesn't mean there's isn't someone out there that will patch it up, but you should think twice about having them do it.

Updated pics - this fork is toast
 

Well folks, I sanded away the paint from around the bottom of crown and here's what I found (see pics). Yep those look like cracks in the fork crown metal to me. Damn. Here's the thing, it will be difficult / expensive to replace this fork. First of all it's a nice light lugged steel fork - designed to go with the Reparto Corse frame of course. Regardless I'm not sure anybody makes anything that would replace it. It's got a 1 inch threaded steerer tube. That is hard enough to find these days, I went to couple of places with used stuff (BikeWorks and Recycled Cycles in Seattle) and they had a few 1 inch threaded forks with canti bosses, but the Crown to Axle distances were way too high. They probably came off cheap hybrids is why. They were easily 1 to 2 cms longer than my fork. My fork has a Crown to Axle distance of 380mm. I don't want to upset the geometry of my racing cyclocross bike by throwing in a fork thats 1 to 2 cms too tall. Even if I'm willing to go 1 inch threadless and replace my headset and stem, I looked around online seems like any new fork I could get has a crown to axle of ~400mm. Why? Are we all supposed to be running 2.1 inch knobbies on our cross bikes?

If any body has or knows of a source for a fork that would work for me I'm all ears. Otherwise I'll have to look at having Rodriguez make me a new fork for $$. I'm trying to stay low budget on this rebuild!

Sorry to hear that. :( That stinks.

I don't know, and it would take much more to explore, but I suspect the cracks may not be the issue they seem to be. They originate in an odd place, where the braze to the tube seems OK. Cracks from mechanical stress don't originate in the middle, so I would have expected an area where there was a gap in the braze, or for the cracks to run out to the inside of the steerer. There's also an odd symmetry, and some kind of line in the same area on the opposite side.

I suspect hat these may be cracks from heat stress during brazing, or some kind of shallow defects in the crown's casting or forging. In either case they would have been there all along. Of course, rust could have made them worse or to where they extend deeper in the crown.

I'd so some exploration, and have an expert framebuilder, preferably one who's worked with cast or forged crowns take a look. I'd also probe for depth with a fine needle, and see if you can cause any movement when stressing the blades with the steerer in a vise.

If All checks out, I'd arrest the rust, then clean and seal them with either silver solder, or even epoxy resin, then paint the bottom of the crown with a clearcoat so I could keep an eye on it for any changes.

I'm not sure that any bike repair shop or even frame builder would touch the fork. In my experience, they're all petrified at working on such an obvious issue. That's especially true considering the litigious environment that any shop or builder has to contend with in doing any sort of business. If they repair it and it subsequently fails, injuring the rider, it "might" just end their career with an embarrassing lawsuit. I've taken a fork that had equally serious issues and not one shop or frame builder would even touch it.

All that to say, don't expect a shop to be eager to do the work.

A Frame builder could make a reasonable functional replica .

Brand New all components.

then You go find a Professional Painter of bikes to re apply the right celeste and replica decals .

Dont as how much Im not that Painter.

^+1, great idea!!

FBinNY is correct in his assessment but the cost of investigating how bad these cracks really are plus the constant nagging concern if if will fail while in use would make me retire it immediately. If the frame has enough value to you, either find a suitable replacement fork or have one built.