.
...p.s. a lot of the good or bad results from welding thin wall tubing like bike tubing is dependent o the type of steel tubing in question, the wall thickness, and the skill of the person doing the job. So this is not the same thing as some kid's gas pipe frame.

In this particular case, the Vitus frame tubing was meant to be brazed together, using less heat than welding, and lugs at the junction points for additional strength and surface bonding of the braze. I personally would not dump much cash, time, or energy into trying to fix that with a welder... not even a tig or a mig welder. I used to weld some, and I wouldn't trust a weld repair on that even if I did it myself. The material is not suitable.

Given enough money, time and expertise, anything is repairable. What most of us are saying is that your bike isn't really worth the money and time even if you can find someone skilled enough to fix it. The components are obsolete, you admit it doesn't shift well and the frame is fractured. Time to move on.

The seat tube needs to be replaced. Once you figure in the cost of removing the damaged tube, cleaning out the bottom bracket shell and seat lug for a replacement tube, brazing the replacement in and repainting the frame, the cost of doing a proper repair would be comparable to replacing the entire frame with one of similar quality.

It may be possible to weld a bead across the broken gap, but contamination from brass in the original brazed joint might interfere with this, and even under the best circumstances I wouldn't expect it to last long. Plus, it would be ugly as sin.

It's had a good life, now it's time to move on.

The only French-thread components that might give you trouble are the bottom bracket cups and headset. The crank looks like a Stronglight mod. 99, so worth keeping if possible. English thread cups should be available to make this work, and failing that, cartridge bottom brackets are abundant. Headsets are cheap, and a replacement frame on the used market may already have a suitable headset installed.

Pics of the actual bike:

I'm thinking along the lines of a quick and dirty repair.
If it gets uglier, that's actually not a bad thing ... if the bike is ugly it's less likely to be attractive to thieves (although I did receive a rare unexpected compliment a couple weeks ago, "that's a nice randonnée bike!"). The ghost shifting I've dealt with for seven years ... it's not a big deal, it's like a friend with a injury.

It's a little bulky but would serve as a theft deterent.
Do they sell one for downtubes?

ok, ok... if you insist on fixin' that beast....

remove the cranks, front derailleur, and bottom bracket......open up the hole that vents the seat tube to the bottom bracket, if it's not already the full ID of the seat tube.... a 1/8" collett, 90 degree head, porting hand piece will work for this operation, the 1/4" pneumatic 90deg. tools will be too darn big to fit in there, and the tool i described might be a really tight fit, too!.... then, fit a very close fitting sleeve of similar steel into the seat tube from inside the BB.... you will want to drill some 1/4" holes thru the seat tube and seat tube boss on the BB... drill them at differing heights to avoid creating a shear plane in the tubing... have a VERY SKILLED welder TIG the sleeve in place via those holes i mentioned...... then weld around the cracked area of the tube, but i'd only partially stitch that crack... once again avoiding a shear plane, ok?... fill any remaining crack with JB weld as a crude bondo.... carefully grind smooth any weld bead protruding past the tube diameter( or just leave it, what the heck, eh?).... sand and paint.... reassemble bottom bracket, cranks, and rear derailleur... tune the der...
Done.

the repair i described will actually be stronger than just the tube and BB shell....

and if you impart too much heat while welding, all the other brazed tubes will try to pop out of place, so a frame jig should be used....

total cost... more than a decent used frame that fits you better.

get a different frame.

"quick and dirty" repair...

find a piece of chrome moly tubing that has an inside dia. similar to the OD of your seat tube... bore out one end to fit snugly over the BB boss of the seat tube... cut that piece of tubing to about 2" long, then split it vertically into two halves... driil holes in it BEFORE you cut it in half(easier to chuck in the drill press vice!), at various different heights REMEMBER, do not create new shear planes..... sand all paint off the areas of your frame to be welded, right down to bare metal, and do so at least a half inch above/below any weld areas... 1" will be better for the welding, btw... tig weld the crack.... remove any high bead areas... then stitch the shells in place, but not all the way around their tops or bottoms... remember. do not create new shear planes! there is a reason that frame lugs have those fancy edges...they spread out the loading.

sand and paint to taste... reassemble/tune... done.

oh, and sanding Bottom bracket shells clean is a pain... trust me on that.

My beloved Europa, which I bought new in the early 80s and have ridden since, died early this year. In my case, the seat tube developed a crease and then bent backwardsm bowing out the seat stays to suit, no actually cracking (on the outside anyway). Sure, it's steel and I could get it repaired, and it's a special bike to me, but it's just not worth the expense.

OP, buy yourself another bike. There are lots of options from another old steelie right through to a new bike, it all depends on your needs and finances. You can buy anything from a frame to a complete bike. I'm currently riding an ugly as sin, four year old KHS which I found cheap while I work out what it is exactly I want/need and while I work out how to finance it. I suspect my best advice is to follow a similar route.

Seems like you have a soft spot for this particular bike. maddog34 has come up with a couple of what might be tongue in cheek suggestions. Perhaps similar thoughts but...

Remove cranks, bottom bracket and front dérailleur along with anything else that might get in the way. Source some steel tubing that matches the inside diameter of your seat tube. Cut a length of it, say three inches? Drop it in the seat tube from the top and work it down so it is protruding into the bottom bracket but would not foul the spindle when you put things back together. It should bring the seat tube into alignment with the part of it that is left in the bottom bracket. See if you can close the remaining gap.

Stand the bike upside down.

Get some Silver Solder and the appropriate Flux. Wind or form a couple of rings of the Silver Solder around the piece of tube that is protruding into the bottom bracket. Mix up the Flux and layer it over the Silver Solder. Get a, big, propane torch and play it over all the local surfaces. Watch the Flux and Solder. The Flux will eventually melt.

Whilst you have to or will get the all of surrounding metal up to temperature when the flux melts concentrate around where the crack is. Eventually the Silver Solder will melt and 'wick' in between your new piece of tube and the original seat tube. Rumour has it it follows the heat. When it disappears remove the heat and leave things to cool down.

Perhaps someone else can comment on the method and if it makes any sense improve on it. The most I have done is fit a pair of bosses for down tube shifters on a frame.

Oh... I guess the main problem will be getting the Solder to wick past the crack. I think JohnDThompson knows a bit about this brazing stuff.

attachment disorder

About 15 years ago, I had a friend (I use the term "had" because he is now riding in the great velodrome in the sky) who's frame that he raced on in the 60's cracked exactly where the OP's did. A guy who owned a local shop used this method to repair it. My friend said it rode fine.

...the one I have is a surprisingly pleasant bike to ride upon. Flux and solder don't work worth damn unless the surfaces to be joined are clean and free of crap...which will be the biggest problem in attempting this.

Anything physical can be fixed or replaced with an exact copy. The question is whether its cheaper to buy something that suits you even better, or put a lot of money in a bike that doesn't really fit,and doesn't function well, and may break again after the repair. To fix that bike you really should take all the parts off, unbraze the top tubes and seat stays, unbraze and remove the broken seat tube, including the fragment in the bottom bracket, create a fixture to hold the frame angles in place properly while you braze in new stuff, braze in a new seat tube, and braze back on the lug for the seat tube, top tube, and seat stays. Then blast off all the unburnt paint (blast it all off: harder to match old and new paint that to just paint the thing), and reprime. Wet sand. Repaint. Wet sand. Repaint, add decals, and clearcoat.

Or, you can risk welding. Typically frames that are lugged are lugged to avoid affecting the frame material adversely. Reynolds 531 is a good example. Heat treated, its super strong and durable. Welding gives poor results. Even if you do get a good looking weld, the Heat Affected Zone (HAZ) will be weak. And would break again, probably at the same location! After you'd gone through the work of repainting.

In short: buying a replacement frame that's better than what you have now: $50-250. Fixing the frame: $300-1000. And oh, by the way, the rework might affect the bottom bracket lug which could break itself.

The French/rest of the World fitup question is valid, but most issues (bottom bracket and headset, I'm thinking) are easily solved much more cheaply than fixing your old frame.

Tough to say goodbye to "old paint". I just did with my Paramount. Sniff... But there's a time when you have to shoot the thing in the head and get a new horse.

...the genius here is that they extended it so the trailing end could be used as a rack. :)

That was in the back of my head but I forgot to mention it. Thanks for the addition. It may or may not be a Road To Fail but the OP seems to have mates with the skill and knowledge required.

Apparently, nothing new under the Sun, it has been done before,

If it was mine and I wanted it back.. I would visit Ebay and buy some Silver Flo with a packet of flux. Dollar parity would make it $15-$20. $5 for a bit of tube. $25 tops. No doubt I would end up in a worse situation than I am at the moment. I would not mind the sunk cost for trying. However if I got it right I would be suffering miles of smiles because someone else has told me it cannot be done.

and I would have my bike back.

.. a reasonable cost for a frame builder with his investment of time, materials and all the machine tools needed that he paid for..
to replace the seat tube, will perhaps exceed what you may be willing to pay..

Now if it feels perfect to ride, the same frame builder could make a copy frame exactly the same , but with more common BSC standard parts.




....

That's brilliant except the OP lives in NYC.

It is illegal to lock your bike to a tree in NYC.


-Tim-

...damn.:( It's always something.

After reading through the replies I'm convinced that it would be a project, not a causal undertaking.
There's also the consideration of the top of the seat tube where it connects with the frame ... if there's some movement/play at the end of the seat tube where the tube has sheared, there has to have been some movement at the other end perhaps impacting the integrity of the connection.

As mentioned, the shops and technicians I know run well equipped shops and are skilled at assisting in large scale stuff all the way down to jewelry making; college shops dealing with sculpture and industrial design, including machining, forging, and lost wax bronze casting (all of which I've done in the past, but not extensively). One friend, who works as a shop tech used to do bike repair and some frame building ... I think it was from the difficulty of scrapping together a living from it and having a kid that prompted the shift of gears into the security of the technician position ... he has a killer front rack that he designed and fabricated that's immaculately fabricated.

The bike has some sentimental value ... after all it was a gift, it did undertake an adventure before I received it, but more chalked up to seeing me through a lot here in NYC. It's the longest I've had a bike in NYC: 7 years without being stolen or vandalized is notable ... that itself feels like some sort of 'luck'. Though now in my 50s, I still consider myself a fairly aggressive rider in NYC (my formative bike years were in the 1980s with no bike lanes, when Mad Max style taxi and bike messenger jousts were common ... bike chains swinging into glass and taxis sideswiping bikes) ... and when my feet find air instead of resistance due to the ghost shifting while trying to dart through a holeshot in an intersection, I curse this damn drive chain, lol. I routinely carry 40lbs (groceries and chain) and if it's on the rear rack the steering is always a little wonky (but I assume that's going to be the case with anything except a touring geometry). Ideally for a commuter I'd like to have an inexpensive beater with a lightweight compliant frame, which is nimble and responsive but also stable with a load, reliable shifting and good brakes. Nobody likes to get a bike stolen, but it can't be too expensive because that kills the utility of locking it up without excessive worry. This Motobecane is on the heavy side, is too large, ghosts shifts.

Fantasy
I suppose the ultimate commuter, one that is a real joy to ride, would be a fairly lightweight compliant tough carbon fiber frame, but in an total package that resembles a beater steel bike, with a aged and rust camo paint job making it, and it's components, appear to be unworthy of any theft.

Real World
Unfortunately, I've been shopping for another bike, but I'm waiting for a once in a year sort of luck in a used bike, something along the lines of a Surly Long Haul Trucker or Trek 520, to try my hand at fully packed touring. My thought was it might also be used for an occasional large grocery haul ... although my position with regards to bikes in NYC is that if one isn't OK with it being stolen than one should never lock a bike out of sight ... they can disappear very fast.

So, I wasn't planning on budgeting for two bikes. The bike touring thing is going to have to wait until next year due to my schedule, but I want to be able to leap on a deal when it presents.

Thanks a bunch for all opinions, ideas, and repair suggestions.
I suppose it's time to start looking for a new daily ride.

Ergon paddle grips on flat bars are pretty nice...

.
...I'm sorry, but what you are looking for is a unicorn. I think there's a method for finding and capturing them, but it requires a virgin.

http://weirdlittleworlds.com/wp-cont...ien-Millon.jpg

OP: For many years I had a 1977 Motobecane Grand Jubile - black with red trim and gold-painted filets on all the lugs. Beautiful bike. Took one test ride on a 2009 Specialized Roubaix (all carbon fiber) and bought it on the spot (in 2009). Finally rode the Motobecane again a month later and the steel bike I'd loved for years was downright dowdy. And that plush steel ride with its luxurious steel fork was hammering me mercilessly by comparison.

It's time to move on.