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O/T need info on rivet type/install

bll230

Hot Rolled
Joined
Jun 14, 2007
Location
Las Vegas
Bicycle gear shifting is synchronized so the chain moves to the next gear, except the shifts are not perfect, just good enough. I finally decided to adjust the spacing between the gears so the shifts are much more accurate.

For stiffness the larger 6 gears are attached in groups of three, with the middle one not being able to mount independently, which didn't allow changing the spacing of the sets of three. Recently Campagnolo started selling a different design gear set with only the larger triplet, and by combining two different gear sets I was able to get the the smaller triplet in separate gears, so I was able to shim the spacers of 8 of the 11 gears to get near perfect shifting. Now I want to make my own triplet for stiffness using the spacers from another triplet with the necessary shims. The first picture shows a drilled out triplet. The rivets are 1/8 inch, odd for an Italian product. Does anyone know if stainless rivets like these are stock item, and is there a press mandrel that produces the flat ends or did Campy probably make custom tooling?

The gears I am using are larger than the one shown and I can allow the rivet head to stick out about 2 mm on both sides.
 

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Perhaps the rivets are 3.2mm = 0.126"

Why not make your own SS rivets and peen them over on the side that doesn't show?
 
I doubt that they are stainless steel. In aircraft applications they would likely be Monel. A 300 stainless will be hard to set due to work hardening. A good sized arbor press should be able to set a Monel rivet.
 
Thank you both for the advice. The suggestion of not using stainless made me realize it doesn't really matter what the steel is, there is grease and oil and dirt over the components, so I took some 12L14 rod I had and made my own rivet, yes it is 3.2 mm, counter drilled the end to make it bellmouth out a bit easier, and used my press to smash into place. It worked better than I expected, and certainly good enough to hold together pieces that aren't going anywhere anyway.

With the test run good, I'll make 5 identical rivets and join my shimmed cogs.
 
The shallow dome formed heads look reasonably standard to me. Might have been formed on a big press. Might have been formed with an orbital impact rivet tool. In either case, the rivet tool would have a recess pretty similar in shape to the final formed head.
 
Is this on a freewheel (rear cluster) or crankset? I trust the rivets only assemble the sprockets, and the tongues on the ID transfer all the torque?

I am interested by your claim that sprocket spacing influences shifting. My impression (as bike mech and long-distance rider, several decades ago) was that it was slop in the derailleur cages and spring in the linkages that made shifting messy.
 
Rivet terminology is a little different from what we are used to with screws.

The rivets you pictured are called flat head rivets.

In contrast, a flat head screw is meant to fit into a countersink, but a rivet with a "countersunk" head is called a flush rivet.
 








 
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