Suntour Spirt Derailleur Clamp
 

I purchased a used Suntour Spirt front bottom pull derailleur to install on my 1969 Gitane Gran Sport. The clamp appears to be too small to fit the standard 28.6mm seat tube.
When I try to mount the derailleur on the tube, the gap between the clamp ends is 12-15 mm (12 on the inside, 15 on the outside). The angle created by the gap between the two ends of the clamp make it impossible to screw the two ends together. Even if the ends of the clamp were parallel, it seems I'd need a longer screw.
Is it possible it's the wrong size clamp? Any suggestions how to make it work?

not the undersized one , buy one that fits instead of bodging something that wont.. New FD are Cheap.

Over size and you can shim backdown , or you can 2 part the thing, a braze on FD and a clamp to mount it..


And You can't un saw a plank, once it's cut..

May have bought a used part stripped off an old schwinn varsity , take it back & exchange it ..

1. Have you accurately measured seat tube OD on your bike? A lot of french stuff is anything but standard.

2. Did you buy a derailleur sized for a 28.6 clamp? A lot of the old Spirts came with 25.4mm clamps.

Keep in mind that a 1969 Gitane may have metric tubing, with a 28.0mm seat tube. If you use a 28.6mm derailleur, you'll likely need a shim.

The OP has the opposite problem. The seat tube diameter is larger than 28.6 mm and the clamp won't close far enough.

Right, but since metric diameter front derailleurs are fairly scarce, fair warning about the need for a shim was in order.

An X-GF(in the 70's) had a "Gitane" mixte, it was actually Asian Made. so fractional diameter frame tubes .

There's always the chance that the FD was made for a 1" tube, or (most unlikely but possible) a metric tube.

The first step is to look at the curvature of the body of the FD where it sits against the tube. The right FD will match the tube perfectly. An oversize clamp touches in the middle with gaps on either side, and a small one touches at the sides with a crescent gap in the middle.

Thank you all. A great first experience with Bike Forums.
The derailleur I bought was clearly intended for a 1" tube (25.4mm), no doubt it came off a Schwinn Varsity. The seller did not indicate a tube size, so I assumed 28.6.
And yes, my Gitane seat tube is 28mm, not 28.6, so I will need to use a shim with a 28.6mm FD clamp.

I have a bunch of NOS SunTour front Derailleurs. Let me know if you'e interested an I'll send you a list of choices tomorrow.

Thanks for your offer. After reading the responses to my initial post I ordered a NOS Spirt specifying 28.6. So I'll wait to receive it and hope it fits.