Remove Small Amount of Chrome to Check Crack
 

I bought a frame, but unfortunately it got damaged during shipping. The seller forgot to add dropout protection on the rear, so there were several alignment issues that I've hopefully fixed, and I'm satisfied with the compensation he gave me.

Anyway, the worst issue is a crack in what I'm thinking (hoping!) is only the chrome, but I would like to remove the chrome there to make sure the steel isn't cracked. How would you do that? An amateur framebuilder said sandblasting, but I don't have access to a sandblaster. I have a Dremel, sandpaper, files, etc... I'm beyond aesthetics at this point. By the way, the crack doesn't go all the way around, it wraps maybe half or two-thirds of the seat stay.

https://cimg4.ibsrv.net/gimg/bikefor...5543c3290e.jpg

My guess is that the chrome "shell" is cracked, but not the underlying steel. I am not sure how to check further. Dye penetrant or magnaflux will not work.

That's what I'm hoping. I'm going to build it up anyway and ride it to see how it goes, but it would ease my mind a little to have a look at the underlying steel. Hopefully I'll get a thread going soon when the bike's complete.

I have a frame that was media-blasted and it was very, very difficult to get a good "edge" when we tried to blast the chrome on the rear triangle. The best we got was a dull finish; we didn't even get through to the zinc or nickel plating. You might see if you can get an X-Acto blade underneath and try to peel a bit back - maybe you can get a visual that way.

When it comes to cracks I don't assume. If you really want to know, find a place that can strip the chrome chemically. Then you'll know. Were it me, I wouldn't ride it until I could trust it.

DD

An alternative to chemically stripping (hydrochloric acid typically) is to utilize a reverse electro plating method that may be easier to control.....read that to mean less risk of removing the base metal. Details abound on the web. If you are not up to doing this yourself, a chrome plating shop could.

Like DD, I wouldn't ride this until I knew for sure......I'm an old guy that takes a long time to heal up!

Dean

OP,
Just a thought, could you build a well with artist clay and fill the void with rubbing alcohol/acetone to see if it flows into the crack? I am not sure but it would seem that the liquid would flow freely/rapidly into the crack before evaporating.
As others have said I would not ride it until I was sure that the frame was safe, a crack in that area of the frame could be dangerous.
Best, Ben

Or maybe drip/spray something inside the tube through the vent hole, see if it leaks out.

Gentle flexing, especially when paired with liquid penetration, should tell you the story. Stress on seat stays is slight so I would not be too concerned about riding. If it is indeed a crack, riding should pretty much verify it.

Too bad it's not on the drive side - you could cut the stay and install a belt drive coupler.

So, I don't know if there's a crack in the steel under the chrome, but there is definitely a hole there... Not sure what this means in terms of cause, but I guess I would need to get rid of the rest of the chrome to see the whole problem.

When I recieved the frame I noticed that I could flip the frame over slowly and it'd sound like a rain stick. I thought this was brazing material in the frame, but maybe it has to do with this? Anyway, I don't know what my options are at this point to make the frame usable.

https://cimg5.ibsrv.net/gimg/bikefor...831ec62db7.jpg

Seems like you might have a big rust problem inside that stay and maybe other tubes on that frame.,,,
That seatstay is shot......

Bummer - that seatstay is a goner. Did you make / enlarge that hole, or was it received like that? (The crack very well could have been initiated at the edge of that hole if the seatstay was under tension.) Bad internal rusting would just exacerbate the situation.

Unless this is a very special frame, It's probably done. You are looking at probably north of $1000 to have that seatstay replaced, and the rear triangle re-chromed. (To do it right. Probably still $200-300 just to get it fixed to where you can rattle-can it and ride.)

Even worse, that kind of rust usually doesn't happen in a vacuum. I doubt the other seatstay is any better.

Unless the frame is exceptional or really really wanted, it would be considered toast, in my book. Yes, it can be repaired, but at considerably cost, particularly if you want to re-chrome anything.

As for riding the bike - not a snow ball's chance in, well you know where. The bike is unsafe, in my opinion. Sorry to bear this news. I have been there, more than once and it is disappointing, to say the least. If the sale was through Ebay, you will be able to recoup your cash. If not Ebay, I don't know what to suggest.

Well it's a pretty nice frame, but I guess not worth fixing if it ain't easy. I'll have to find another one since the build was basically complete. Does anything from the pre-shipping pics suggest problems? If the frame hadn't of gotten messed up in shipping, I would have already been riding it, how would I have known it had damage inside?

I have more pictures, but the uploader is acting weird... Let me know if you want to see any other details.

https://cimg2.ibsrv.net/gimg/bikefor...06e6a058e5.jpg

https://cimg8.ibsrv.net/gimg/bikefor...1956b62052.jpg

https://cimg0.ibsrv.net/gimg/bikefor...2462cfc734.jpg

https://cimg5.ibsrv.net/gimg/bikefor...a70bebc324.jpg

https://cimg7.ibsrv.net/gimg/bikefor...1b74a9fa89.jpg

Well, the plot thickens...

It appears to me that someone drilled the hole to prevent propagation of the crack. It's not an original vent hole because one can be seen about an inch above the crack.

It's obvious now that the crack didn't occur during shipment. Are we getting the whole story?

DD

And then it was chromed over? Here's a picture of the same area before shipping:

https://cimg9.ibsrv.net/gimg/bikefor...d927ca50fe.jpg

The first post tells us about the crack. Nine posts later we are presented with another view of the crack with a hole - this was never mentioned previously. Now a photo that doesn't appear to show an additional hole on the NDS seatstay. Was the hole there when you received the frame? I ask because you made no note of it at all in your initial post, and that is somewhat surprising given you're looking to find out if the frame is structurally sound or not.

The only reason to drill a hole at either end of a crack is to stop the crack from getting bigger. If that hole/crack combo was there when you received it and he didn't disclose, you should get your money back.

DD

I used an exacto knife as you suggested to probe the crack, and the hole is what I found. It wasn't there in the pictures before shipping. I didn't notice the crack until I was realigning the dropouts due to shipping damage (the axle slot was closed up a little, the adjustment screws were bent, and the dropouts were not parallel). So, basically, most of that hole was under the chrome.

If you poked at the chrome with the X-acto knife and got a hole out of it, then the metal has rusted away to nothingness from the inside. My thoughts are rough handling in transit was the straw that broke the camels back exposing the invisible. I am hesitant to lay blame with the seller in this case.

Had the seller taken proper precautions with shipping you would be riding a ticking time bomb and never known it. Given the seller compensated for shipping damage already, I take that as a good faith effort. It sucks that it turned out to be a bad egg.

I haven't a clue now what's going on here. I'm unsure of the timeline and who's done what. I am skeptical that chrome's properties would allow it to mask over a pre-existing hole. The manufacturer's vent holes aren't closed by the chrome and they appear of smaller diameter than the crack-stopping hole.

DD

It wouldn't have masked over a pre-existing hole. The hole didn't exist until just now. The hole would have began on the back side and progressivly developed over a long time. The chrome was the last few .0001 inch before the rust/corrosion pitted all the way through from the inside. Messing with the drop out only exposed a problem a long time in the making.

Basically, there was water in there at some point, an electrolyte formed by some minerals and oxygen then bonded with the iron atoms until...well, no more bike. It was never visible from the shiny side because outside the tube is a different environment than inside. Short of an ultrasonic inspection or a borescope the eroding wall would never be discovered until a service failure.

I consider the OP lucky he dodged a bullet.

It sounds like the inside of the stay was rusted almost all the way through. The shipping damage, or re-alignment efforts caused the remaining steel + chrome layer to crack leading to the initial photo by the OP. The OP then dug out and formed the hole at the end with an x-acto blade top.

It doesn't sound the the seller really did anything wrong, other than poorly packing the frame. If you look at where the vent holes are located, there appears to be a good 1.5" below them for water to sit. Every time it was ridden in the rain, or washed, you could have a large slug of water that might take weeks to evaporate. Even worse, plating acids and salts if not washed out really well will cause rapid corrosion, often to the point of tube failure. That large cavity under the vent hole may have lead to poor inital cleanup, and a good dose of hygroscopic salts sitting there waiting to go to town.

So, is the rain stick effect an indicator of this or could that indeed be brazing material inside the frame?

I guess I could still try to remove more chrome to see what the rest of the stay looks like. Having a frame rusted on the inside when the outside looks pretty good must be fairly rare, right?

That stay is shot. No need for further digging. The other side???? Probably not great either. The rain stick effect is a bad sign in general. It isn't unheard for small gobs of brass or flux to wind up loose, but it's not super common. Even then, it would just be one loose bit, not tons of stuff like rain. (Sand could have gotten in there too, but rust is more likely.)