badmother

Hop we can get some help for a problem w a damaged toptube. The tube is not damaged from a crash, so the rest of the frame is fine, and since the frame is the biggest we could find around here (62 cm) we hope it is possible to replace the toptube.

It is a low end 1980`s Gitane, lugged. I`ve got a similar Mixte that I really like, so we hope to repair this bike.

We are both new to this (but not to metalwork like welding and brazing) and need to ask:

I hope remowing the old tube is just about to cut it twice (take out a part in the middle) and then heat one side at the time to get the pieces out.

I am more worryed about fitting the new toptube. Can we just carefully bend the frame and put the new toptube in?

I guess silver brazing is the way to go.

And first of all: Buying the new toptube is a challenge, no framebuilders around here. Found this online: https://www.metals4u.co.uk/products.a...FdsU3god5S55Lw
Can I hope to buy something from them suited for our repair?

Wery happy if somebody can help!

sannerbikes700

Hey there,

You've got the right idea on removing it. Take out a section, then remove 1 side at a time.

It can be a bit of a challenge getting each side out though. What I do is position the lug upward, and sweat as much brass out of the lug and down the tube as possible. Then when you've gotten as much out as you can, heat around the whole lug with a big ol' flame and wiggle the tube out. Getting the tube to come loose can be pretty hard with brass. It will probably be a little messy, and you'll want to go in with a small grinder tip and clean it up in there afterward.

As for a new tube you could probably use mild steel, but if going through the trouble of replacing a tube you might as well use a cromo butted tube... they are not that expensive. Where are you located? Peter at Ceeway is in the UK and ships anywhere www.ceeway.com

Maybe someone else here has better tricks for removing the tube...

badmother

Thank you wery much!

bobbycorno

I'd recommend measuring the diameter of the top tube before you get a whole lot of time and money tied up in this. Older French bikes used a 26mm diameter top tube, vs 25.4 (1") for everybody else in the world. Gitane might have switched to 25.4 by the early 80's, but you'd do well to check it, as metric frame tubing is pretty much unobtanium.

SP
Bend, OR

badmother

It is 26mm for sure! I remember measuring it to approx 26,1 including the paint. That is only 0,6mm bigger than a 1" , 0,3mm "on each side". You say we can not just fill it up with soldering? Where the toptube hits the headtube and seat tube (innside the lugs) the hole going trough the head and seat tubes into the toptube is only approx 10mm (+/-) so the top tube is kept in its place by the two other horisontal tubes.

sannerbikes700

If you braze the new 1" tube in with brass you shouldn't have a problem.