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O.M.A.S. bottom bracket? On a what?

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O.M.A.S. bottom bracket? On a what?

Old 07-06-22, 07:41 PM
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RandolphCarter
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O.M.A.S. bottom bracket? On a what?

So I dragged home an Allitalia bike a few months ago:



It has an interesting bike boom era mix of parts. Suntour Cyclone derailleurs, Sugino Super Mighty cranks, KKT pedals, Weinmann brakes, Jim Blackburn rear rack.

The hubs and rims are so dirty I have no idea what they are, Front rim is steel and rear is alloy.

It's surprisingly light.

I want to use the cranks on another build so I pulled them. Since the bottom bracket was in much better shape than other parts I have, I pulled that too.

And scratched my head a good while.


The cup says "O.M.A.S Italy" and "36 x 24F"

Neither side is a fixed cup, they both have lock rings.

Sealed bearings that are still smooth:




The spindle is a very high quality piece of machining.

Why on earth would a bottom bracket this nice be in a brand of bike I've never heard of?

EDIT: If any of the hive mind here know anything about Allitalia bikes, I'd appreciate it if you shared your knowledge.

Last edited by RandolphCarter; 07-06-22 at 07:45 PM.
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Old 07-06-22, 08:02 PM
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...using adjustable cups with lock rings on bikes with RH threading on both sides was a commonly used trick to create a BB with an adjustment for chain line.
This is doubtless what someone has done on yours. It works well, so unless you are swapping the entire unit out for something else, I would just use it as is.

OMAS is not seen all that often, but it was commonly available back then. It's relatively high quality stuff....probably on a par or better with Campagnolo in terms of durability.
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Old 07-06-22, 08:07 PM
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...I know nothing about your bike frame itself. There were a lot of contract built Italian frames sold here under various names. Check the frame tubing for butting. Either the steel rim is a replacement and a downgrade, or the alloy one is a replacement and an upgrade. Or they are both replacements, for an original high quality set of tubular wheels.
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Old 07-06-22, 10:22 PM
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Originally Posted by 3alarmer
.
...unless you are swapping the entire unit out for something else, I would just use it as is.

OMAS is not seen all that often, but it was commonly available back then. It's relatively high quality stuff....probably on a par or better with Campagnolo in terms of durability.
Good to know the bb is as nice as I had assumed. I had wanted to use it and the cranks in another frame. The other frame is English threaded so that won't work...

Originally Posted by 3alarmer
.
...I know nothing about your bike frame itself. There were a lot of contract built Italian frames sold here under various names. Check the frame tubing for butting. Either the steel rim is a replacement and a downgrade, or the alloy one is a replacement and an upgrade. Or they are both replacements, for an original high quality set of tubular wheels.
I'm pretty sure the tubing is not butted. There's also a seam down the middle of the bottom bracket shell underside. The dropouts are stamped with a bolt on derailleur claw and there are no braze ons of any kind.

There are clamp on Campy shift levers.

I'm thinking someone in a bike shop in the 70s had a few too many beers and leftover parts.
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Old 07-06-22, 10:38 PM
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...that spindle is probably sized for Italian BB shell width anyway, so using it in a 68mm shell is problematic anyway.
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Old 07-06-22, 11:32 PM
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Originally Posted by 3alarmer
.
...that spindle is probably sized for Italian BB shell width anyway, so using it in a 68mm shell is problematic anyway.
Oh, and while you're at it get a magnet and see if it is attracted to the spindle. Titanium?
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Old 07-07-22, 06:33 AM
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Originally Posted by LittleGinseng
Oh, and while you're at it get a magnet and see if it is attracted to the spindle. Titanium?
Magnet does not stick to the spindle. Looking at it in better light it does look like titanium.

I was not expecting to find anything remotely like this on the bike.
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Old 07-07-22, 07:17 AM
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Originally Posted by 3alarmer
...using adjustable cups with lock rings on bikes with RH threading on both sides was a commonly used trick to create a BB with an adjustment for chain line. This is doubtless what someone has done on yours.
That's actually how OMAS supplied their bottom brackets:

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Old 07-07-22, 03:03 PM
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[catalogue page of 1978]

---

frame -

are either of the bridges plate style?

lug pattern: Agrati "AMERICA"

upper head lug: Agrati N. 007.8505

lower head lug: Agrati N. 086.8053

seat lug: Agrati N. 086.8569

fork crown: Agrati "AM" N. 005.8048

dropouts: Agrati N. 000.8002

fork ends: Agrati N. 000.8010

bottom bracket shell: difficult to see clearly; looks like it may be Agrati "AM" pattern

---

remaining original fittings -

Balilla brake levers

3TTT Tourist stem & bar set

Agrati headset

front wheel: Gnutti hub with NISI rim

seat binder

---

original gear ensemble would have been Campag Valentino

original brakes would have been Balilla centrepull

original chainset would have been cottered steel by either Agrati or OMG

original pedals would have been Sheffield all steel

original saddle pillar plain steel

---

possible that identity of manufacturer could be advanced with information on placement and format of serial marking, if present

one possible maker might be Chiorda - mentioned only as a possible

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Last edited by juvela; 07-07-22 at 03:06 PM. Reason: spellin'
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