How to "un-strangle" a seat tube?

[foxb13]

Hi,

Apologies if there's already a thread on this subject, but since English isn't my mother tongue, I may not have used the right words to describe what I want to do (and find the appropriate thread/solution).

Is it possible to "inflate" a seat tube that has been "strangled" by a front derailleur tightened too much?

I know, I'm not clear . So here are pictures of what I'm talking about. The frame is presumably CrMo made with Colombus OR or Vitus Super 983 tubeset.




Thanks!

 

[marc two tone]

Hello, your English is just fine, all very understandable!
That indentation happens alot with Tange ultimate tubing due to its inherent thin walls.
OK, you want to push the dented area back out....I'm an no expert on that subject and access will be exceptionally difficult.

**carefully now**

I've read of filling tube with water, or similar and freeze it, the expansion 'potentially' pushes it out. But how far with an old metal structure with unknown faults....so, forget that stuff for now.

My experience....

Leave it alone and use a plastic shim. My old team marin had some crimping. I bought a 34.9 ----> 28.6mm. Hidden and works well, this prevents the problem getting worse yet, you can carry on riding.

 

[SFP]

All I can say is Bloody frakking hell..... wow....

Someone seriously wanted to make sure it was there tight.

Plastic shim is your best bet

 

[novocaine]

Is it doable? yes. Is it worth it? No.

To do it probably you put a ring round the outside and use an expanding plug to push it out. The tooling is custom and you'd have to make it yourself.

 

[baron von greenback]

It won't work on this but I was thinking on dents on bikes in general you can get like a rivet gun and it welds rods on to the dent then use a sliding hammer to pull out the dent panel beaters use them or I watched a video were they use a block of wood and rotate frame in it

 

[foxb13]

Thanks all for your feedback. Oh yes, "dented" is probably the right word, thanks @marc two tone. Hopefully, the new parts, I intend to build the bike with, will have a front derailleur located at the same seat tube height to cover/hide the dented area.

 

[foxb13]

All I can say is Bloody frakking hell..... wow....

Someone seriously wanted to make sure it was there tight.

Plastic shim is your best bet

Or someone forgot that unscrewing is counter-clockwise. At least for a front derailleur

 

[foxb13]

Is it doable? yes. Is it worth it? No.

To do it probably you put a ring round the outside and use an expanding plug to push it out. The tooling is custom and you'd have to make it yourself.

Ingenious, got it. Thanks!

 

[foxb13]

It won't work on this but I was thinking on dents on bikes in general you can get like a rivet gun and it welds rods on to the dent then use a sliding hammer to pull out the dent panel beaters use them or I watched a video were they use a block of wood and rotate frame in it

Oh yes, I've seen this in many car restoration TV shows. In French, the tool is called "tire-clou". Thanks for the info.

 

[novocaine]

Oh yes, I've seen this in many car restoration TV shows. In French, the tool is called "tire-clou". Thanks for the info.

Works on really thin sheet, not here.

Paintless dent removal uses a hot glue instead of weld to achieve a similar result.