nlerner

Picked this up from a young feller who gave up after trying to remove a stuck stem and seriously bending the fork blades. Seems like a decently made frame. Early 80s, maybe? Fork is out and soaking in penetrant. Park fork alignment rig stands ready.

bear_a_bug 

Incredible balancing act getting the frame/fork home in your pannier!

Sad to see the fork like that. Some folks just don't know when it's time to put the hammer away and find a gentler solution. Working on figuring out that wisdom myself...

Looks a bit small for you. What's the plan?

PilotFishBob 

Poor thing. Those stays and fork - misguided attempt at a fat bike conversion or just random lunacy?

verktyg 

It's a 1983 Motobecane Jubilee Sport with a frame made of some kind of lower cost Columbus tubing, maybe straight gauge Aellle.

About that time, Motobecane, Peugeot and Gitane all brought out lower to mid range priced bikes with lugless construction.

This was different than classic lugless brazing which built up a thick fillet around the joints - see below. Motobecane called their process "INEXTERNAL BRAZING" and their BS marketing artists billed it as something new!

The technique has been used for many years for brazing furniture and lots of other products made of tubing. It entails using "preforms" made of brazing alloy placed inside and/or outside of the joint to be brazed. The joints are then furnace or hearth brazed.



In reality it was an attempt to save money over lugged construction frames to compete against the low cost Asian bikes that were taking over the market.

The reason I've mentioned all this is the paint at the seam where the down tube and head tube meet doesn't look right. The person who applied enough force to bend the forks that much could have over stressed the brazed joints too!!! I'd inspect the head tube joints carefully.

BTW they're not lugs on the head tube, it's been rolled to look that way.




I've never seen a frame failure in the lugless French bikes made that way in the early 80's but there sure were a lot of braze and weld failures in CHEAP department store kid killer bikes before the CPSC rules came out. That was one of the stupid reasons for crash testing bikes....

verktyg

nlerner

Ah, thanks, Chas. There is an "inexternal" Columbus decal on the seat tube that I'll get a pic of. And I'll inspect the welds at the head tube. I did notice that the brazing from fork crown to the inside of the fork legs is really sloppy. Just big blobs of material.

Plan-wise, if I can sort out the fork issue, I'm going to build this one up with parts on hand and sell it off on my very hot CL market. I have a couple of replacement forks, but the steerers are too tall for this little thing (and the guy who gave it to me was probably 6', so I'm not sure he imagined actually riding it). I've been searching for a new pandemic project, so . . . I do need to determine what the BB threading is. I'm hoping it's late enough in the marque to be English, but I won't hold my breath.

steve sumner

pretty sure the BB threads are Swiss

unworthy1

I re-worked an identical frame for a co-worker some 7-8 years ago to make him a daily rider (he bought the frame off CL). Kind of liked the frame's lightness but decided the fork looked nicer than it was strong, and was appalled with the internal cable passages in the TT that are just holes punched/crimped in the tube! So Crude! But do not remember that the BB threads were Swiss, I think that detail would have registered.

SurferRosa

​​Ohhh. <lightbulb> That's what's going on there. (Whew.)

nlerner

Here’s a closeup of the tubing decal:



I played around with the BB, trying some known English cups and some known French cups. I didn’t force anything, but I think the threading might be Swiss. Yuck.

SurferRosa

Better than French.

nlerner

So the latest wrinkle on this Moto project is routing brake cable housing through the crude channels under the top tube (pic below). One end goes in, but does not emerge from the other hole but just keeps traveling along the inside of the tube. I tried it with an inner wire, but same problem. Any creative ideas?

Charles Wahl

Gotta think like an electrician . . .
Start with a thread or fishing line (maybe tie a knot or two in the end) fed in through one orifice, with a vacuum cleaner on the other end.

When you've got that through, then move up to a flexible wire (like stainless fishing leader, use the woven thread to pull that through. Hardest part is fixing that to the brake cable housing. You might be able to drill a tiny hole (think eye of the needle) to feed the small wire through, and loop/twist that back on itself; whatever you do, it has to fit through both holes -- only one and then failure means starting over.

If you're lucky, and use strong enough fishing line (Dyneema or Spectra) you might make it work with only that, and no wire. And it's possible you could simply tape it to the housing for some distance.

Pick up that brake adjuster on the mats, or lose it.

bikemig 

Given that you're selling this, I'd be tempted to just use zip clips and the brake cable housing externally. I dunno if I'd trust that fork though.

Nice, nice job of balancing that bike on the back of your Bridgestone.

nlerner

Thanks for the ideas, Charles and Miguel. Figured it out by running a length of solder wire (rigid enough to emerge at the other end, where I could pluck it out with a needle nose pliers). I then inserted the solder into the housing and pulled it through.

Miguel, I’m giving up on that fork. Stem is still stuck, and my straightening efforts have improved it, but it’s pretty much a basket case. The frame is currently wearing a 1” threaded carbon fiber replacement that I had in my stash!

nlerner

Got it! It’s for the rear Shimano brake on this bike. Wouldn’t have been fun to inadvertently kick that into a dark corner of the basement (which is pretty much every corner).

bikemig 

That bike has serious street cred in the greater Boston market with a carbon fork. Price it accordingly,

nlerner

Requisite basement pic of the work in progress:

SurferRosa

The carbon fork asks, "any aero levers in the bin?"

nlerner

You know, that did occur to me, particularly with the aero cable routing, but as seen in the original catalog pic that Chas shows above, non-aero brake cabling. Also gave me a chance to hack off the extended ends of some Weinmann levers set up for turkey wings that I had in the bin though I had to use a set of nice Cane Creek hoods I’ve had for awhile. Parts bin Frankenbuilds are the best builds.

repechage

good you retired the fork. Was going to ask about the dent under the top tube- answered.
like Chas’ I don’t like the appearance of the head tube/ downtube weld right now... test, don’t guess... would not be good to sell it off and have the head tube start to tear away.

These Moto’s seem to have long top tubes for their size. I have a Champion Team from the 753, Columbus era and the top tube is over 1cm longer than I expected.

gugie 

Having spent considerable time in Neal's Man Cave, one could bin build a bike out of what's stuck in the dark corners.

Charles Wahl

Yeah, maybe he should have a parts-finding party in his basement (with social distancing), with props and a T-shirt for the piece that has the best current "completed listings" price on eBay. Neal's probably lost more parts than are in most peoples' hoard-inventories.

xiaoman1 

Looking quite good...I was wondering about the "crimps" along the top tube as well as the seat post-BB, I like those details...glad you used the rod idea for snaking the cable, it has always worked for me..just like a plumbers snake you sometimes need to twist/rotate it a little to get it in position.
Looking forward to the next steps...Aero levers as suggested may be the ticket.
Best, Ben

nlerner

The last three years in February I’ve hosted my old Brit bike group’s “shop day” in my basement. There are always projects laying around, including stuck bolts, stems, dust caps, etc. I managed to give away a bunch of stuff the last time, but the bins and dark corners still seem to be filled (though no aero levers I’d be willing to sacrifice for this build; hmm, actually I have a mismatched set of Shimano levers—one 600, the other Dura Ace, hmm). I’ve decided to go with SunTour friction shifters and derailleurs for this build and was looking through the secondary box of FDs (the primary box contents are too nice). Found four candidates that got a bath in the ultrasonic, including two Spirts. Just seems like the right kind of build to feature a Spirt derailleur.

CV-6 

That rear triangle is something. Pencil seat stays and majorly crimped chain stays. Quite the contrast to the beefy looking carbon fork.