harrell53

Hello, new to this forum and I have come for some frame repair advice.

I bought a 2000 Bianchi Eros bike off Facebook marketplace as a restoration project. I may have got ripped off on the price ($240) because the bottom bracket and headset both needed to be replaced, and then I found a crack in the frame. I don't really care though because I think it it is a cool bike that deserves to be fixed up and put back on the road. Long story short the crack runs lengthwise along the bottom side of the drive side chain stay. It looks like it may have formed from a combination of rust inside the frame and/or a defect in the material during the tube forming process. The frame is one of Bianchi's Chromolite double butted frames. My question is, what is the best approach to repairing such a crack. Tig weld a bead over the crack to close it up after drilling some small stop holes and reshaping the tubing a bit. Cut out the crack and Tig weld in a patch using similarly shaped chromoly tubing? Or, braze the crack with a possible patch brazed on over it for extra insurance. My concern with Tig welding this area of the frame is that the material here is very thin, and I'm afraid that welding it will make it too brittle and cause further cracks or failure to form further down the road. The guy I bought it from was riding the bike on a regular basis and was probably not even aware that the crack existed. This tells me that the bike is still structurally sound enough that it does not need a major repair to be ride-able again.

I have moderate experience with welding but am out of practice, and I have very little experience with brazing. I am a fast learner, and can do just about anything the correct way my first attempt if I do enough research. Some of my friends are willing to give me access to their equipment so that I can do this repair myself.

I am a little infuriated that this site will not allow me to post pictures on my thread because I am a "newbie". So if you think you are able to help me with this issue please PM me so that we can communicate by phone and I can share pictures.

shelbyfv

I suggest you post this in the Framebuilders section. https://www.bikeforums.net/framebuilders/

harrell53

Can this one be moved? Or do I simply create a new one?

shelbyfv

I've asked a mod to move it for you.

Pop N Wood

If it rusted from the inside out I would be very hesitant to try and patch it. The fact the internal bearings are dead makes me wonder if that is water related as well.

Litespud

If this is internal rust manifesting as a crack in the frame, welding the crack isn't going to do anything. Once the rust has worked its way to the surface, the crack is just the tip of the rustberg, and there's likely very little left to repair - the chain stay is likely fatally compromised. I see this in old brit car frames - once the rust emerges, it's time to cut out and replace the affected section - there's no good way to repair it, because most of the metal is rotted. Another possibility (a better one, frankly), is that water in the stay froze and burst the tubing - that way, at least the metal wasn't eaten away, just ruptured, and might be repairable. It might be a cool bike, but an Eros isn't that special that I, personally, would go to such lengths to rescue it.

ClydeClydeson

When my old CCM steel frame had a rust related crack (underside of the seat stay, IIRC, similar to what OP described), I brazed a patch over the crack. I made the patch from a piece of a chainstay cut from an old junker bike.

harrell53

Someone tried to send me a PM and apparently I cannot even receive PM’s because of my “noobie” status. While I understand needing to protect the community from spammers, this seems like a petty way to do it. I guess I’ll just have to play along and keep posting till I can get some pictures up.
The rust is not that bad and I do not think it was the cause of the crack on further inspection. It is a “normal” amount of internal rust for a 20 year old steel frame. I was able to use a punch and hammer to close up the gap after drilling small holes at both ends of the crack to prevent it from growing while I hammered on it. The steel all seems structurally sound, and the crack is only about 1.5” in length. I do not think anything needs to be cut out and patched, but I’m still a little torn between Tig or brazing being my best option.

harrell53

I was able to send a picture of the crack to my mechanical engineer friend and he was the one that suggested that there was a defect in the steel tubing during the forming process. He is also the one who suggested I reach out to the bike community for advice.

harrell53

Also, to any nay sayers lol. I love the idea of salvaging old stuff that others think is junk. I'm willing to do whatever it takes to make this frame last for years to come, anything short of dumping hundreds of $$ into it. The paint stripping process alone is pretty tedious.

unterhausen

sorry for the anti-spammer rules. I know it is annoying and a lot of people don't want to wait 2 days and 10 posts, but we used to have to ban a lot of spammer and now we don't. So the rules are staying.

If you post pictures to your gallery and mention it here, someone will rescue them for you

dsaul

It is fairly common for chainstays to crack from water pooling in the stay and then freezing. From your description of hammering the crack closed, it sounds like your crack was bulged out, which is a telltale sign of freeze damage. A normal crack from forming the stay or dimpling would not open up to the point of needing to be hammered shut.

The correct repair is to replace the stay, but that could be expensive. If it were mine and I wanted to continue riding it, I would have no issue with TIG welding the crack. As long as there is no rust and the area can be cleaned properly, it should be fine. If it cracks again, it won't cause a catastrophic failure.

My gravel frame was finished and I was cleaning it up before sending it to the powder coater, when I discovered a crack in the chainstay from some aggresive dimpling. I didn't want to cut the stay out and replace it, so I welded up the crack. This photo is of the welded up crack, before I filed and sanded the weld smooth. After powder coating, you would never know it has been welded. I have done thousands of hard miles on that bike with no indication of the crack returning.

unterhausen

I didn't expect the crack to be on that part of the tube

dsaul

It started out as a 3/4" round tube and I dimple it into a "D" shape on an arbor press. In this case, I was smashing a 19mm round tube into an 11mm wide "D" shape and there is a fairly sharp bend at the top and bottom of that dimple. Cracking at that spot is always a concern for me and I pushed this one a little too far.

unterhausen

I think that may be why they used to make an indent instead of a flat dimple. It's actually less sharp at the edges of the dimple. Unless I'm misunderstanding what you did.

harrell53

Thank you (dsaul), the crack you welded up is a lot like the one I am dealing with. It makes sense what you said about ice making the crack open up a little like it did, but it also could have been from use/stress. Your success story has given me the courage to just try welding it up and hope for the best. There really wasn't much rust damage to speak of so it should be a simple repair and I can move on and not worry about it. Thanks everyone for your input, I'll post again to show how the welding went and put up some pics when I am able to.

Andrew R Stewart 

You can learn a lot from repairing frames. Many times the lesson is what not to do in the future Andy