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Can this steerer be repaired?

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Can this steerer be repaired?

Old 05-11-16, 08:07 PM
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notsoimpossible
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Can this steerer be repaired?

Background: My husband bought us a 1973-1975 era Gitante tandem off of CL, for us to ride together. I've always wanted a tandem and I really love this one. It needed to be cleaned up and serviced, so I'm attempting a complete overhaul (for the first time ever).

From my understanding this is a lower-quality "gas-pipe" steel frame. It's French, so many non-standard components.

I got the fork off today only to discover this crack.



How bad is this? Is it dangerous to do nothing? (I assume so) Can it be repaired, and if so, is it going to be expensive?

The fork looks to be in otherwise good condition.

Thanks for your help!

Last edited by notsoimpossible; 05-11-16 at 08:17 PM.
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Old 05-11-16, 08:31 PM
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That's not good. I would look at replacing the fork, possibly with a rigid fork designed for off-road use. These often use a strong "unicrown" design (where the fork blades are welded directly to the steer tube) and can accommodate wide tires, which means you should be able to use the 700C wheel original to the bike. These should be available in either threaded or unthreaded versions, either of which will mean installing a new headset.

It's a bit of work, but you should be able to get your tandem back on the road with a safe fork and not too extravagant investment.
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Old 05-11-16, 08:57 PM
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So repair is definitely not an option?

I suppose I should have included a picture of the whole fork:


And the bike in it's entirety:


I really love the vintage aesthetic of the bike (and the fork in particular). I think a unicrown fork would look out of place on this bike. Also, the bike still has 27" wheels. If repair is absolutely a bad and unsafe idea, then I'd want to replace with something more period-correct.
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Old 05-11-16, 09:59 PM
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You can't do anything about the steerer, but I'd be OK riding it as is ------ provided you properly install the stem so it extends well below the last thread, including the entire wedge area.

This is one reason I prefer the European split tube/conical wedge system over the angled wedges used in the USA and far east. The split tube system places the greatest hoop stress on the steerer at the bottom, well beyond the cut threads if the stem is inserted deep enough. The angled wedges carry that stress much higher, and often are not inserted deep enough to prevent expansion forces in the threaded area (what most likely split your steerer).

So, go ahead and use it, but push the stem lower, or replace it with one of the other design, or both.

BTW - it is possible to braze the split and rethread it, but it takes some skill to do right, and it will only restore some of the original strength, probably less than half. So if braze and thread will make you feel better about the fork, I can give you a name. But keep in mind that you still have to make dead sure that all stem expander stress is well below the unthreaded area.

There may be a nice alternative, taking a hint from the Civil War south. Being short of steel they cast their cannons thinner and reinforced the breech by winding rods around them. You can do something similar starting below the threads actually used by the headset, and following the helix down to the last thread. You'd need high strength steel wire, like piano string, and have to be careful about the gauge because of limited clearance but I can see the possibility of a very workmanlike repair that would make the fork as strong as before, or maybe even stronger.
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Last edited by FBinNY; 05-11-16 at 10:21 PM.
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Old 05-11-16, 10:31 PM
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Originally Posted by FBinNY View Post
You can't do anything about the steerer, but I'd be OK riding it as is ------ provided you properly install the stem so it extends well below the last thread, including the entire wedge area.
This is an answer that I am happy to hear

Interestingly, the stem on this bike is the European style you say you prefer. It must have been installed too high.

I had already been considering replacing the stem, as I had read elsewhere that the old french stems were prone to failure. I think I'll go with something like this: Amazon.com : Nitto Technomic 26.0 60mm 72d Silver 225mm 1" Quill Stem : Bike Stems And Parts : Sports & Outdoors and really have it inserted far, for peace of mind. (Are there any issues with having too much stem in the steerer?)

If anyone knows someone in the northeast Ohio area who could do the repair, I may still be interested in having it done. I will for sure keep an eye on the crack and make sure it doesn't grow. But not having to source a new fork, get bosses brazed, have it painted, etc will surely save me a lot of headaches
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Old 05-11-16, 10:43 PM
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Sometimes you can't win for losing.

The stem type is perfect for the job except that it won't fit.

French forks have an ID of 22.0mm, vs. the 22.2mm of this stem. That can be worked around with some sandpaper and patience, but I don't think French bars are 26mm (though don't trust my vague memory on this).

Otherwise, there's no issue pushing stems or seatposts deeper, except that fork steerers are usually reinforced at the crown, typically extending up about 2" or so, so that would be a limiting factor.

For the record and your peace of mind, understand that the milled flat on your fork is extremely thin at the middle as the curve of the ID meets the flat of the flat like this )[. So even new and in perfect condition there's not an awful lot of strength there. As i said, it doesn't matter as long as the stem is deep enough because, excluding the expanding zone, the stem wall not only doesn't stress the fork, it actually reinforces it, and threaded forks are dependent on that, which is why stems must extend below threads, even if there's no milled flat or keyway.
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Last edited by FBinNY; 05-11-16 at 10:54 PM.
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Old 05-11-16, 10:44 PM
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The fly in the ointment of the plan to use that Nitto stem is that the quill is 22.2 in diameter, but you would need a 22.0 stem.
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Old 05-11-16, 11:23 PM
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notsoimpossible
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This thread has been very informative, thanks!

I think I'll definitely go with a new stem. To get the current stem low enough for safety would require inserting it all the way down, and with the stem shifters (3" long levers) it may look kind of odd, if it works at all.

I'll plan to sand down a 22.2 stem to fit the french fork - seems simple enough. I may not go with the stem I linked, but I'll figure out the diameter of the current handlebar clamp area and order whatever is closest but just larger, and shim to fit.
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Old 05-11-16, 11:31 PM
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We also have an old Gitane tandem. While riding it to work one day in '77 the steerer tube cracked just above the bottom race with the result that the fork and wheel came off the bike and the bottom of the head tube smashed into the pavement (along with my hands and chin). We took the bike to a local frame builder (Colin Laing) and he installed a new steerer tube in the fork and reshaped the bottom of the head tube. It was a very inexpensive repair (but I may have gotten a sympathy discount for my bandages). In any event, the repaired fork/steerer worked well and is still in use. It did require some repainting around the crown of the fork.
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Old 05-12-16, 01:18 AM
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That is a pretty bike.

I like the idea of just putting it back together and riding, while moving the stem lower (both structural support, and preventing it from expanding the crack more) The headset should give the top of the steer tube adequate support.

The weakness appears to be a flat section of the steer tube for an anti-rotation washer, or perhaps for the centerpull or canti brakes upper cable guide/stop.

There are quite a few people who sand stems down from 22.2mm down to 22.0mm, taking off about 0.1mm around the entire stem. It isn't enough material to significantly weaken the stems.

So that extra-long Nitto stem may well be just fine with a little adjustment.
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Old 05-12-16, 02:50 AM
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I bought a Motobacane a couple of years ago, very similar bicycle. Even the same goose poop color.
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Old 05-12-16, 03:22 AM
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If you're going to sand a 22.2mm stem down to a 22.0mm diameter i'd use something to dye the area you're sanding so that you can see what's been removed. Once the area is all bright silver I'd measure it and then dye it again before any further sanding is done. Putting the sanded stem into the steerer each time you sand the stem and dye it might show you exactly where more metal needs to be removed from the stem. I find emery cloth works very well as you can clamp the stem, use two hands to work the cloth around the stem whilst sanding to keep the stem round.

If there's a bicycle co-op near you they might have the correct diameter stem.

Good luck and cheers
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Old 05-12-16, 04:09 AM
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IMO, yes it can be repaired by brazing and may not even require filing since it is at the flat.

p.s.----NICE looking bike....ENJOY!!!
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