HI
I have an old handcrafted titanium frame from the 90s, made by an Estonian craftsman, to be completed and fixed here and there as it has never been used, the threads need to be revised, and the seat tube needs to be filed

There is no seat post tube and no seat post clamp.

I wonder, titanium seatpost clamp, 28.6mm: does it make sense? is it too fragile for 28.6mm? if not, does this exist? where to find/buy one?

This one will need some images, the words do not conjure up a frame for me yet.

This is the frame I am talking about.


this is a Litespeed's clamp. I don't know if it's made of steel, allu or titanium, but ideally it has the shape I'd like to have.

28.6 mm is a common size for seat post collars:

https://www.porkchopbmx.com/vintage-...8-seat-clamps/

But are you also saying there’s no slot cut at the top of the tube?

I think I see the top of a slot when I pinch the screen.

I am wondering if the OP is wondering if titanium would work?

When you say seat tube needs to be filed, do you mean reamed and squared at the top?

Also, what do you mean by “there is no seat post tube”? Like a sleeve or shim inside of the seat tube?

Yup, the frame was not finished, there were a lot of things to do, e.g. not fully polished, so I did that, then I drilled and tapped the bottom of the bottom bracket for an M4 screw to be able to install the cables guide jig for derailleurs, all the threads had to be redone, the head tube had to be milled 1/8mm to install the headset in the photo I have installed a Campagnolo Victory), etc, and the seatube needed to be reamed and squared at the top.




I meant not included with the frame like it often happens with Litespeed, so I bought a Campagnolo Super Record 26.6mm one

Yup, precisely my doubt: I have never seen a titanium seatpost clamp of 28.6mm!
The smallest is 31.*mm: why?

• because it too difficult to build it with Titanium grade 5, 6al-4v ?
• because it will be too fragile?

Titanium grade 5, 6al-4v? will it work with 28.6mm? if yes, where to find and buy one?

28.6 mm seat post collars made of aluminium were common, now they are more difficult to find, but yes, you can see something on eBay and Amazon; I haven't seen a titanium one that size yet, and those in steel (Magristroni type) are for smaller diameters.


When I received the frame there was no slot, I created one, copying the shape and size from another bicycle.

This is a nice aluminium clamp, Thomson-mod2682080105, 28.6mm, silver.

clamps like this are all over ebay. You need an accurate OD meaurement of your seat tube.

Try to find a clamp that does NOT have the bolt threaded into aluminum, but instead has a floading nut that can accommodate the angle change as the collar tightens.

DiTBho you paid a lot for that seatpost. The clamp bolt is real easy to damage if you are tightening it with a pipe wrench or channel lock pliers. Find yourself a really good 6 point box wrench in 13 mm to avoid damaging that bolt. You can also use a 13 mm socket, recommend a Snap On SFSM131. Replacements are hard to find and expensive.

/markp

I'm seeing no shortage of aluminum 28.6 clamps on AliExpress: https://www.aliexpress.us/w/wholesal...ost-clamp.html

There are several Ti fabricators in China who might make one for you.

The 28.6mm Thompson one is rare on eBay, as >=31mm are usually listed, but I can order a 28.6mm from a physical shop for 25 euro (so, cheaper than on eBay)

The point was/is: I have never seen any Titanium one of 28.6mm.
Why?

Yeah, the Thompson one looks this way.

Thanks for the tips about tools!
I never mentioned how much I paid for the Campy seatpost.
I don't think 50 euros new old stock is too much.

you will pay that for a replacement bolt if you damage it.

/markp

The titanium collar clamps are less available because of cost to manufacture a very small demand, and lastly.... for those counting gram's, they weigh more than the svelte aluminum offerings.

Haven't seen a clear photo of the seat tube (ref. the frame seat tube) but suggest drilling a relief hole at the end of the expansion slot. Also, for that smaller diameter titanium tubing, the seat post fitted to the seat tube should be a slightly tighter tolerance than just slip fit. Focus on this and then the pinch clamp is less stressed, plus allows one to seek the lighter weight, elegant type without concern.

Ample selection of 28.6 seat post collar clamps on ebay. The Thomson is nice and from a long time supplier to the aerospace industry, consider its reliable. Its pricey and double cost many other offerings.

I wouldn't be hung up on seeking a titanium clamp as there's many aluminum, light in weight and attractive designs. Try Omni Racer as example.

In titanium, you might be able to reach out to asian supplier like J&L. They're pretty decent to correspond with. (side note: I had a new seat post from them but noticed a flawed rail clamp. They agreed and promptly replaced.)

Dave Levy at TiCycles will probably be happy to make you one if you are truly prepared to step up that far.

https://www.ticycles.com/contact

I sent him a message, we will see.

I bought a MSO (digital mixed signal oscilloscope) from Rigol, a great Chinese company, but I don't generally trust Chinese companies, especially on Aliexpress and eBay, as they usually they sell garbage!

I'm writing this as I'm about to return two titanium bottle cages that I bought from two random Chinese companies on Aliexpress, that were welded so badly that they cracked!

And, sht!, we are talking about 500ml of water in a super light Bianchi Barcellona aluminum bottle: titanium requires proper skills and equipment, especially the grade 5, requires cold working and welding that does not expose it to oxygen, otherwise it loses mechanical properties, and if they are not capable of welding a simple bottle cage that is stressed at less than half a kg in weight, imagine how much I can trust a saddle collar stressed by 66Kg in weight!

Dave is the guy and will help if he can.

Agreed, he made me a real nice titanium stem for the Dinucci that is a perfect compliment to the bike.

the bolts in the pic above are from Jim Merz, they are titanium and super sweet.

Point is, you can get stuff made that is the equivalent of anything out there, but it will cost you.

@OP what is the diameter of the seat collar (bare tube) on your frame ? measure carefully.

/markp

As in the synthetic image I prepared, the diameter of the bare seat tube on the frame is 28.6 mm.
Actually, it's 28.55 mm, measured with a twentieth caliber.

okay. That Thompson clamp posted above has an important feature, and that is the floating nut that can rotate to accommodate the change in circumference as the clamp bolt is tightened.

reduces bending moment on the bolt.

also that nut is steel ! Don't pay money for a clamp (titanium or any other material) where the bolt is just threaded into the base material.

I have one like this on my ebike - replaced the standard clamp. works very well. 2nd pic

add a chinese titanium bolt in rainbow anodize from eboy for style points and you're all set for the coffee shop.

Titanium in particular is prone to galling. if you get a fancy titanium clamp and the bolt is threaded into the material, you'll have problems for sure.

/markp

There are many good anti-seize lubricants available that will resolve the galling issue and anyone with a Ti bike should have on their bench.

can you suggest a good anti-seize lubricant?

Permatex Anti-Seize Lubricant and Finish Line Anti-Seize Assembly Lube are messy stuff but worth the trouble.

while it's always a good idea to use the bull butter of choice, be it grease, carbon paste, whatever

this particular application does expose the clamp bolt to bending stresses. The floating nut fixes that problem.

you guys can pick your "best cheep" Amazon goop. I'd go with NUCLEAR GRADE Anti Seize, yes it is NERC / AEC approved. Loctite N-5000 is equivalent.

When people see this on your workbench they KNOW you are SERIOUS

/markp