INEXTERNAL PROCESS - mbk

hi there,
I am owner of this bike
http://www.allegro.pl/item138978903_mbk_mirage_pro.html
I have question about "INEXTERNAL COLUMBUS TRI CROMOR PROCESS".
What is this all about ?
I don`t trust the way they connected "the pipes" - I prefer much more
traditional style - for example
lugged columbus steel frames.

regards,
Mariusz

mariusz wrote:
hi there,
I am owner of this bike
http://www.allegro.pl/item138978903_mbk_mirage_pro.html
I have question about "INEXTERNAL COLUMBUS TRI CROMOR PROCESS".
What is this all about ?
I don`t trust the way they connected "the pipes" - I prefer much more
traditional style - for example
lugged columbus steel frames.

regards,
Mariusz

Nice bike!

I remember "inexternal" from Pugeot, but Pugeot may be related to MBK.

The "Inexternal" refers to where the brazing takes place, which is a
brass fillet *inside* the tube, rather than outside. I'm guessing it
helped with the automated robot brazing machine, and makes joint clean
up easier (non-existent?). Maybe the brass was even a ring inserted
before brazing, rather than added from a rod by a human during brazing.
All in all, an innovative way to connect steel tubes.

I wouldn't worry about the frame's strength. I don't think I ever saw a
broken Inexternal joint. But it does look a little unusual.

wrote:
mariusz wrote:
hi there,
I am owner of this bike
http://www.allegro.pl/item138978903_mbk_mirage_pro.html
I have question about "INEXTERNAL COLUMBUS TRI CROMOR PROCESS".
What is this all about ?
I don`t trust the way they connected "the pipes" - I prefer much more
traditional style - for example
lugged columbus steel frames.

regards,
Mariusz

Nice bike!

I remember "inexternal" from Pugeot, but Pugeot may be related to MBK.


Peugeot was French. Motobecane, also French in the past, became MBK.


The "Inexternal" refers to where the brazing takes place, which is a
brass fillet *inside* the tube, rather than outside.

IIRC, this refers to internal (plug in) lugs. Motobecane had some bikes
like this in the '80s.

Also, IIRC, Columbus Cromor was a lower end tube set.


I'm guessing it
helped with the automated robot brazing machine, and makes joint clean
up easier (non-existent?). Maybe the brass was even a ring inserted
before brazing, rather than added from a rod by a human during brazing.
All in all, an innovative way to connect steel tubes.

I wouldn't worry about the frame's strength. I don't think I ever saw a
broken Inexternal joint. But it does look a little unusual.

mariusz wrote:
hi there,
I am owner of this bike
http://www.allegro.pl/item138978903_mbk_mirage_pro.html
I have question about "INEXTERNAL COLUMBUS TRI CROMOR PROCESS".
What is this all about ?
I don`t trust the way they connected "the pipes" - I prefer much more
traditional style - for example
lugged columbus steel frames.

regards,
Mariusz

This site shows a Motobecane catalog that talks about "inexternal"
brazing.
http://www.equusbicycle.com/bike/mot...motobecane.htm

Especially this page
http://www.equusbicycle.com/bike/mot...becane0003.jpg
shows a diagram of the braze inside as well as outside the tubes.

wrote:
mariusz wrote:
hi there,
I am owner of this bike
http://www.allegro.pl/item138978903_mbk_mirage_pro.html
I have question about "INEXTERNAL COLUMBUS TRI CROMOR PROCESS".
What is this all about ?
I don`t trust the way they connected "the pipes" - I prefer much more
traditional style - for example
lugged columbus steel frames.

regards,
Mariusz

Nice bike!

I remember "inexternal" from P[e]ugeot, but P[e]ugeot may be related to MBK.

The "Inexternal" refers to where the brazing takes place, which is a
brass fillet *inside* the tube, rather than outside. I'm guessing it
helped with the automated robot brazing machine, and makes joint clean
up easier (non-existent?). Maybe the brass was even a ring inserted
before brazing, rather than added from a rod by a human during brazing.
All in all, an innovative way to connect steel tubes.

I wouldn't worry about the frame's strength. I don't think I ever saw a
broken Inexternal joint. But it does look a little unusual.

Readers of rec.bicycles.tech:

I am of the opinion that the "Inexternal" joints look BETTER than
external lugs [1], especially those with frivolous ornamentation. (Now
I have likely offended a lot of people!)

Of course I may be biased, since my first bike store quality bike was a
Peugeot with internal lugs.

[1] However, I do like the appearance of the Kabuki Submariner
bicycles, with the oversize cast aluminium alloy lugs and unpainted
stainless steel tubing.

--
Tom Sherman - Post Free or Die!