Leftydad

First time posting, was wondering if someone could tell me whether or not I should just give up.

If I uploaded this image successfully, then you can see part of a very old and somewhat tattered Velosolex Saint-Tropez frame. The frame was built with a derailleur hanger attached. I found the frame with a broken Simplex derailleur bolted in. When I removed the broken Simplex, I found that both of the derailleurs I had sitting around had bolts too large to fit this hanger (I had assumed all of these bolts on all derailleurs were simply the same size). Also, if you can see, the hanger doesn't have that little groove in it along the outside, but instead is a perfectly rounded (too wide) circle.

Is there a derailleur that is made for something like this, or do I have to go back to 1970's France to find one? If anyone could give me any advice I would really appreciate it.

jyl

Your bike has a derailleur hanger for Simplex derailleurs. On the Simplex derailleur, there is a stamped metal tab on the derailleur that limits its rotation on the hanger; on the "standard" derailleur that everyone uses today, there is a "b-screw" that contacts a notch on the edge of the hanger to perform the same function. Also the Simplex derailleur hanger is not threaded. You can read more here (the first link is the clearest):

Links
Upgrading Bicycle Gearing
French Bikes

You can modify the hanger to accept "standard" derailleurs. Have a bike shop tap the hanger to the standard threading, costs $10-15. For the notch, you can use a file or better a Dremel tool to carefully cut a notch in the appropriate part of the hanger. Copy the notch location/size on a bike with a standard hanger. If the B-screw doesn't quite engage the notch, you can sometimes reverse it so that the head of the screw engages the notch.

But, purists will say you should not modify the original Simplex hanger. If the frame is valuable or you are a purist, then eBay will turn up an original Simplex derailleur, and they can be fairly cheap.

Here is one for $42 - not so cheap but it is a nice one, and you won't have to fuss, it will bolt right up. https://www.ebay.com/itm/used-vintage...item259137a2ef

You can see, in the photo of the backside of that Simplex derailleur, the stamped steel plate with the bent tab, and the nut that secures the derailler to the hanger.

oldskoolwrench

Based on your photo, the drive side dropout is bent; that's why the slot is wider than the LH side. Look closely, just 'below' the dropout screw... see the rippled paint? That part of the dropout (which just happens to be the thinnest section) has been fatigued and weakened. Compounding the issue is the fact that the metal is even thinner there because the dropout was drilled for the (now bent) screw, which took out even more material.

Your derailleur issues aside, the dropout is the big Kahuna; it needs to be aligned back to where it matches the LH side. Your LBS might be able to re-align it, or you could give it a shot. Either way, be prepared for the fact that it could break, or be extremely soft, to where it makes the frame unusable.

If everything turns out OK, I would carefully drill out the derailleur hanger and re-tap the hole. Another job for the LBS, for they would have the tap size to match the current threading used.

jyl

Suppose he rode it like that. Maybe push the axle all the way to the end of the slot. Would it "work"?

Sixty Fiver

That dropout needs to be repaired, a dropout without a stop screw might be cold set under certain conditions but with the stop screw cold setting it back will further compromise the dropout.

The stop screw and Simplex hangar is a sign that you might have something a little nicer than the run of the mill Velosolex.

oldskoolwrench

Possibly, provided that the bent screw (after the bent end has been cut & filed flush) will come out easily. The back end of the slot is also distorted slightly,
leaving more slop for the axle to shift up/down since it still isn't flush inside there.

There's still the work noted earlier to drill, re-tap and cut the notch for the B-tension tab...

If the OP decides to straighten it himself, maybe use a C-clamp, with the fixed side inside the dropout triangle,
and the adjustable side against the end of the derailleur tab? A slow turn might be just enough to move it without excessive force.

jyl

The reason I asked, is because I wonder if it is better to take the risk of damaging the dropout while trying to realign it, or to simply assemble the bike and see how it rides. If it rides okay, I personally might not chance the cold setting. But I am timid, and lazy.