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-   -   Remove Small Amount of Chrome to Check Crack (https://www.bikeforums.net/classic-vintage/1159282-remove-small-amount-chrome-check-crack.html)

Drillium Dude 11-02-18 03:15 PM


Originally Posted by base2 (Post 20645326)
The hole didn't exist until just now. The hole would have began on the back side and progressively developed over a long time.

I am not ready to leap to that conclusion based upon the current evidence. That hole looks symmetrical, as if it were drilled. I'd like to see a few more pics of it from a couple angles to be sure.

DD

dailycommute 11-02-18 03:31 PM

That sucks, sorry man....That hole looks a bit jagged to be drilled. Wonder if perhaps the bike was stored via hanging from ceiling from front wheel. Only way I can think that water would have sat inside the frame in that spot. If you flush it and a lot of rust gunk flows out then probably what happened.

base2 11-02-18 03:38 PM

https://en.m.wikipedia.org/wiki/Pitting_corrosion


Originally Posted by Drillium Dude (Post 20645507)
I am not ready to leap to that conclusion based upon the current evidence. That hole looks symmetrical, as if it were drilled. I'd like to see a few more pics of it from a couple angles to be sure.

DD

As a sailor, this was predominantly the reason we engaged in constant preservation efforts on the ship. I've punched a needle gun right through 1/4 inch steel plates where the only indication was a tiny bubble on several occasions. Usually it resulted in a Hull Tech and a welder, a very long day and a lot of extra heart ache. It does seem weird the extreme localized nature of the thing, but in my own personal experience a nearly perfectly round rust hole is a true phenomenon.

xiaoman1 11-02-18 05:46 PM

I concur with what others have said...best that you found it before building and riding it...consider yourself lucky.
Ben

verktyg 11-02-18 06:30 PM

Internal Rust
 
It doesn't take water to cause corrosion in chrome plated steel parts. The electroplating chemicals are highly corrosive and need to be flushed out and/or neutralized. That didn't/doesn't always happen with bicycles. It can take years for the steel to corrode through.

Here's an example corrosion from the inside out with an old chrome plated fork blade. Does that hole look familiar?

https://cimg2.ibsrv.net/gimg/bikefor...601420d4fb.jpg

Occasionally I hang out a a local frame builder's shop. He has a lot of examples frames rusting out from the inside. One heart breaker is an early 70's Colnago with playing card decals. It's red and just my size but sadly the tubes are Swiss cheesed (and it wasn't even plated).

I have a mid 60's bike that's chrome plated under a spectacular paint job. It too has "rain stick" seat stays. I got it from Switzerland about 10 years ago and it sat partially assembled for several years. As I was rotating the frame on the bike stand to work on it I heard the telltale sounds so I pulled the BB to check out the chain stays. They were full of large rust flakes. Unfortunately the bike will remain a wall hanger.

A friend picked up an old uber light weight lugless French constructeur frame at a bike swap. When he got it home he noticed pitting in the fork blades and seat stays. Stage IV cancer!

As someone pointed out the OP's frame is going to be expensive to repair. He can maybe get by with a new rear triangle if the rest of the frame is worth keeping and then save some money by not re-plating it. If the forks are questionable then find a nice place to hang it.

[MENTION=468797]diomekes[/MENTION] et al...

In reference to vent holes in the tubes, the main purpose is to allow gasses to escape while brazing. Without the holes, the heated expanding atmosphere in the tubes can push the molten brazing material out of the joint. On a lugged frame, it's mainly the seat stays, fork blades plus the seat and or head tube that have vent holes. The seat and or head tubes are drilled to provide an escape for gasses in the top tube during brazing.

Grape jelly or marmalade on that frame sir? Sorry... :cry:

verktyg :50:

diomekes 11-02-18 08:28 PM


Originally Posted by Drillium Dude (Post 20645507)
I am not ready to leap to that conclusion based upon the current evidence. That hole looks symmetrical, as if it were drilled. I'd like to see a few more pics of it from a couple angles to be sure.

DD

I used a little pick to probe more once I noticed there was some depth to the crack, that's probably why it looks roundish.

Drillium Dude 11-02-18 08:36 PM


Originally Posted by diomekes (Post 20645848)
I used a little pick to probe more once I noticed there was some depth to the crack, that's probably why it looks roundish.

I defer to the guy who has his eyeballs on something he can hold in his hands. I did download the pic and zoom in, but I couldn't tell what was a hole and what might be surface rust after you flaked away some chrome.

What is sad is the frame looks in nearly perfect shape from the outside. Not even any spidering going on under the paint. Big frame, so it's not like you have lots of opportunities to find nice stuff in a size that fits you. I know you've been compensated somewhat, but you've ended up with a frame that is structurally unsound and will only serve as wall-hanger art. I hope you aren't out too much hard-earned money as a result...

DD

diomekes 11-03-18 09:07 AM


Originally Posted by verktyg (Post 20645708)
Grape jelly or marmalade on that frame sir? Sorry... :cry:

Both, please? Yes, the hole looks very similar to that hole you posted, or at least I'm guessing it would if I removed all the chrome.

I guess I'm on the hunt again for a mid '90s race frame to use a 7400 groupset on. I've wanted one every since I missed out on a local Merckx Motorola TSX frame with the same groupset for $500! I'm thinking TSX, SLX, maybe EL, or even Tange Prestige would be nice.

I am out money on this frame, but not too much in the scheme of life (between $65 and $100 given the seller's refund, and hard to calculate exactly since it was a couple of transactions with several items each). Anyone have ideas on what to do with a nice TSX frame without stays? I might see if someone around here that's started framebuilding wants a project.

Thanks for helping me figure the frame's issues out.

verktyg 11-03-18 10:04 AM

If it weren't for the rain stick sound, I might consider it a localized problem at the bottom of that seat stay which could easily be replaced sans chrome. Do both sides have that "death rattle"? If so that's bad news. I'd go over the whole frames carefully looking for any signs of pinholes in the chrome. A good frame builder could give you a diagnosis in a few minutes...

My rain stick is a $2k wall hanger! :cry:

verktyg :50:

dddd 11-03-18 05:14 PM

The OP could beat on the suspected areas with an aluminum rod, to verify if this cancer is widespread.

If not, and since this is a relatively fail-safe location for a frame to break, it is fathomable that the tube could be filled (from the bottom up, from another drilled hole) using JB-Weld, injected in using a syringe. I've done this to a carbon frame's seatstay, and I trust the plugged tube with it's 5,000psi-rated plug in it.
As with this frame, the Giant carbon frame had an intact seatstay but for a large contusion on the rear side of the tube, the result of the derailer and chain trying to wrap 360-degrees around the cassette.

Before attempting any repair, I would fill the tube with oxalic acid solution, wait several hours, then flush, repeating several times until no red tint in the solution issues forth. This will present bare metal to the filler and result in a tighter fit of the plug in the bore of the tube.

diomekes 11-03-18 07:14 PM

I'm pretty sure it's just the seat stays with the sound, but definitely both of them. It seems only the non drive one got damaged in shipping.

​​​​​​​I'll try washing them out with that solution at least.

​​​​​​​Oh, what does the aluminum rod do?

dddd 11-03-18 07:32 PM

You just bang on the stays to check for any other areas where the steel has gone missing behind the chrome layer!

Just don't hit the main tubes too hard, they dent easily, but the seatstays aren't butted thin so can take a hard tap, and the chrome won't be scuffed by aluminum.

Also, the JB Weld is quite rigid, and is much stronger than 5,000psi in compression.

verktyg 11-04-18 10:26 AM

Darwin Awards!
 
HEY! WATCH THIS! Your guide to joining the Darwin Awards! https://darwinawards.com/

5,0000 psi??? From their website: " J-B Weld has a tensile strength of 3960 PSI"

The weakest aluminum alloy has a tensile strength of 15,000 pis. The Aluminum used in beverage cans has a tensile strength of 37,000-41,000 psi. 6061 aluminum alloy is 40,000 to 45,000 psi. Alloys steels used in bike frames are ~120,000 psi....

JB Weld products are adhesives or fillers not a structural materials!!!


https://cimg4.ibsrv.net/gimg/bikefor...55baecf802.jpghttps://cimg3.ibsrv.net/gimg/bikefor...b3b36282dd.jpg

https://cimg2.ibsrv.net/gimg/bikefor...63ff262f26.jpg

verktyg :50:

diomekes 11-05-18 08:39 AM

There are those that live to tell the tale. For those that don't, well, we always have the Darwin Awards.


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