Lotus907efi

I just received a Vitus Carbone9 in the post today. As can be seen from the photos someone did a terrible flatbar conversion to it.
The used a MTB trigger shifter for the rear derailleur along with a single downtube shifter for the front derailleur.
This along with the el'cheapo white brake levers were the first things I stripped off of the bike when I pulled it out of the shipping box.
As received the bike has a Shimano Golden Arrow rear derailleur, a Campagnolo front derailleur, a Mavic headset, a Stronglight 175 crankset with 48/34 chainrings and a set of Shimano 105 Super SLR brake calipers.
There is also a matching pair of Mavic 192 NE rims laced to some Exage FH-HG50 hubs.
The biggest problem is the bike is missing the original seat post. Normally this wouldn't be such a big deal but this frame has one of the smallest diameter seat posts I have ever heard of at 23mm.
As a work around some previous owner had shoved a piece of 23mm aluminum tube down into the seat post and then had a hollow Kalloy seat post with a 23mm ID cut off and stuck onto the aluminum tube sticking up out of the frame. A real butcher job. It took a LOT of work to get that 23mm aluminum tube out of the seattube without damaging the frame.

Has anyone ever seen a road type of seat post that is 23mm in OD?

I know such a thing exists because there is a seller from Romania with a Vitus Carbone3 frame for $500 that actually comes with the 23mm seat post as part of the item listing https://www.ebay.com/itm/403891748821

So I am in search of a 23mm road type of seat post like the one shown in this other ebay auction listing.


Lotus907efi

What the seat post should look like


nice 23mm fluted seat post missing from my new bike

Lattz

Congrats on the bike, once I missed out by a few hours on the lo-pro version.

aanyway....
Someone has one over here in the German classifieds since last September (I guess there are no hordes of Carbone 9 owners out there)
https://www.ebay-kleinanzeigen.de/s-...96406-217-3499

If you want, I can ask him, if he's willing to post it to the States, but I quickly check the other classifieds as well...

Lotus907efi

That would be great. That seems to be the exact part I need.

Chombi1 

The original seatposts used on Vitus Carbone bike was made by Rubis with a 23mm diameter.what was also unique about the supplied (On the Carbones and oater 979s) Rubis seatpost was, it was machined at the back side of the seatpost shat to have a flat vertical strip where the seatpost anchoring grub bolt with the special pivoting tip presses against when you tighten the grub bolt.
The Rubis seatpost comes up once in a while at eBay for sale. It would be best if you get the Rubis seatpost with the machined flat area so it will less likely slip on you while riding.....or you can have it machined yourself if you cannot find the exact seatpost.

krakhaus 

Campagnolo made one back in the day. I had this exact frame, but the bolt chewed a hole in the seatpost. If you do find one, I would recommend finding a clamp to use on the seatpost where it would sit on the seat lug. That way you won't have to crank the bolt down as much and ruin your new one.

Chombi1 

The important thing is to retain the proprietary seatpost anchoring grub bolt that has a special pivoting nose bearing so it minimizes damage to the seatpost it is anchoring onto the seat lug. The pivoting bearing has a flat portion so it does not dig into the seatpost too deep.

Lotus907efi

Thanks for the great info. I guess I am also missing this special grub screw then too. Do those ever come up on ebay or anywhere else I might be able to source one?
Or failing that a picture might help so I could see about replicating one.

Chombi1 

Unfortunately those special grub screws do not come up that often for sale.​​​​​​​I replaced the one on my Carbone Plus 7 some years ago with an NOS one for sale at ebay as the original's allen socket was pretty much stripped out, so I could not tighten it as much as I needed to anymore.​​​​​​​I have only seen a couple of them for sale at eBay since. Maybe I just keekept missing them when they came up., but if you stay vigilant and keep checking regularly, one might still come up for you.​​​​​​​Most of the ones I've seen since were just regular grub screws with a point at the nose. They should work in the meantime but it means that you might have to live with divots at the back of your seatpost shaft that it will make.

Chombi1 

Here's a link to a business that sold spare parts for classic Vitus frames. IIRC, they are from Canada.https://guywires.com/salestuff/vitusparts.htm
Last I heard about them is they scaled down (Or maybe closed down for good?) drastically some years back, maybe because of dwindling old Vitus parts supplies.You can still see the special grub screw listed on their site. Whether it is still available, I dont know......

xiaoman1 

I am not sure, but you might be able to use a standard (metric) hex bolt with out the pivot if the groove is cut in the seat post along with a clamp as suggested. There may be enough surface area to set the post etc.
It's worth a try with the additional clamp in place.
Good Luck, Ben

1simplexnut

I know you can get ball end grubscrews in the industrial world .
Used in SRT bearings by various manufacturers . Your local bearing/engineering supplies shop should be able to get them ?
Would be better / safer than a standard knurled grubscrew.

Lotus907efi

Wow, good find! Thanks 1simplexnut

Chombi1 

Just remember, the pivoting bearing needs to have a small area of the bearing machined flat.That flat area on the bearing is what interfaces with the flat vertical strip machine on the back side of the seatpost shaft.

1simplexnut

I wonder if some cunning engineer could figure out a way to grind a flat on the ball ?

merziac

What a (seat) cluster.

merziac

So gonna ask the obvious question, is the grub screw a standard metric thread assuming you could figure out how to get the flat on the bearing?

Also have to assume the original had a provision for keeping the flat correctly located and only turning rotationally, not something a standard bearing grub screw will do.

1simplexnut

Was thinking about this myself .
I think I need to pull the grub screw from the one frame I have with the grubscrew lock and investigate

Also have been wondering what would be the downside to using the ball type instead of the orginal ?
Point contact from a ball so possibly not a lot of deformation to the flat area (if using the original post with a flat. )
It certainly wouldnt gouge like a serrated tip grub screw .
MAybe not enough area to hold post ?

Will have a nosey at the screw in my red Vitus and see what is what in the morning .
Way past my bedtime now (yawn yawn)

merziac

Well, I think these are sketch from the jump but I can't imagine them holding very well at all if the post could just roll down the ball to slip which brings us right back to the overtightening issue, maybe just crimp the ball, make a flat, carbon paste and hope for the best.

Hondo6

Shouldn't that be Carbone paste?

xiaoman1 

Wondering why one would need a bearing with the flat, wouldn't there be enough surface on the regular bolt to hold the post in place? The angle of the hole looks perpendicular to the post (close enough) , wouldn't the "flat" bearing still be locked in place with the tightening of the bolt anyway losing its ability to rotate? Standard bolt would be the same...what am I missing?
Ben

1simplexnut

Well I pulled the critter out of my red Vitus .
Appears to be correct ? with a flat face to push on the machined flat on the post (should have taken a pic of that too I suppose ?)
The separate tip does not want to rotate but is a different material . Appears to be hardened after a quick swipe with a file .
I see a curve to the od of the tip so suspect a ball with a flat ground in it .
All good fun .






Vitus in red

1simplexnut

hiya - There is a corresponding flat machined in the correct seat post for these frames .
I know what you are saying though . I have a couple of 80s PX10 with an allen head capscrew in the seat tube which locks the seatpost just fine .
Disparaged by most out there but I have never had any issue with it slipping .

Chombi1 

The thread is coarse metric. Don't know the size though....

Chombi1 

The allen head bolt on the 84 Peugeots had a pointy nose to it that dug into the machined groove on the seatpost.it will only look bad if you have to raise your saddle as you will see the divot.I never really liked Peugeot's version of this type of seatpost anchorage as it really puts a lot of concentrated stress on the seat tube and the boss which could eventually lead to them cracking, if you mistakenly tighten it too much.....Peugeot must have thought the same as they only used it for the 1984 model year. Later bikes either went back to conventional seat lug clamping ears or quill seatposts after 84.​​​​​​​