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zach.hope

I have been enjoying learning about and taking apart my dad's ~1973 Super Corsa since I got it a few weeks ago. However, I noticed yesterday upon removing the fork that a crack has propagated within the flattened section of the threaded portion of the steer tube. I have no idea how long it has been there. It seems to me that threaded steer tubes would be subject to less stress than their threadless counterparts, but I still would like some feedback regarding the sanity behind riding this fork. I am not planning on making this bike my daily commuter, but I would like to ride it regularly. Would it be wise to find a replacement fork before I ride this bike? Thanks for your input.

Wisey

NO, NO , NO. PLEASE DO NOT RIDE ON THIS FORK. NOT EVER, NOT EVEN JUST TO TRY IT OUT.

Sorry, but that is most certainly unsafe. If you want to ride the bike, you'll need to replace that fork. Your LBS should be able to get something in plain chrome finish that will match the bike whatever colour it is. If you want to be really fancy, you can shop around for a frame builder who can source a matching fork crown and build an exact replica for you. A lot of expense for not much gain, but certainly possible.

greyhundguy

Zach,
What size is your frame? Contact Wayne Bingham at http://www.veloclassique.com/
He has a good quantity of original NOS Gitane forks for sale. Reynolds 531 and some have the Campagnolo drop outs. He does not have anything for larger frames though. Probably 56 cm and smaller. You might be able to find one in the original color. If not, at least you would have an original fork that could be repainted your color. Most have a TdF decal but that can be peeled off.

Jay

zach.hope

Thanks for the replies. The frame is about 62 cm CtoC, so it may be difficult to find a replacement fork. The steerer is ~230 mm long. I may discuss with some local frame builders the possibility of replacing the steerer, but it seems like the French threading and flattened portion of the threads could be difficult to match (I'd like to keep the French Campagnolo headset). Otherwise, does anyone have decent sources for replacement forks with such long steerers??

verktyg

The split was caused by having the stem too high. The expander wedge at the bottom of the stem caused the steering tube to bulge and split.

This is the reason for a 3" (75mm) minimum stem insertion recommendation so that the expander is below the threads.

If the split was near the top of the steerer it probably wouldn't matter too much as long as the threads were not bulged.

In your situation the threads are definitely bulged and the whole top of the steering tube could break off leaving you holding the unattached bars!

Happened to me once on a test ride of a customer's bike; fortunately I was going slow and was able to stop the bike safely. Shocked

There are several possible fixes:

1. Find a replacement French fork

2. A "competent" frame builder can cut about 4" off the top of the steering tube put a sleeve inside and TIG weld a new threaded piece on to it.

This could be done with just brazing but TIG welding would be as strong as new, especially on a 62cm frame.

3. A "competent" frame builder can cut the old steering tube out of the fork crown with a carbide burr and silver braze in a new steerer. I've seen this done where there was little or no damage to the chrome.

4. A "competent" frame builder can build you a new fork (expensive and probably not necessary).

The biggest problem may be finding a French M25x1 threaded steering tube, especially one that long. Maybe someone could cannibalize a steerer from an old French fork.

5. A replacement fork from a LBS. Tange offers some well made replacement forks plus there are probably some cheap chrome plated steel forks available.

Several problems with these forks. They will most like alter the ride and handling of the bike because of differences in fork length and rake. The 300mm long steerer tube us threaded about 4"+ and you may need one of the long quill Nitto stems to get the wedge below the threads. They have more modern looking fork crowns that take recessed brake bolts.

If you have to go to a British or Italian threaded steering tube, you will only need to replace the top adjustable threaded race, the top lock nut plus maybe the washer or washers. These items are frequently available on eBay.

You will probably have to replace the stem too, 22mm vs 22.2mm.

Good luck...