I was pretty much set on getting an Argon Gallium Pro but my LBS threw a curve ball and have offered me an S Works Tarmac SL4 to replace the SL3 that I've just sold at a really good price. In the spec it says it's a carbon OS BB. I want to run my ceramic Fulcrum RRS that I had on the SL3. Is it any different? I don't want to have to use adapters just the BB cups I had on the SL3. Anyone know?
Thanks
Rhys

As far as I can work out the carbon OS BB on your new frame is a version of PF30 unique to Specialized that is only 62mm wide as opposed to the alloy BB30 of your SL3 that was the more common 68mm wide. Really speaking it only works with the BB30 Specialised cranks than come with special spacers to make up the extra 6mm. There is a company called C-Bear that apparently makes an adapter for UT cranks to run in a carbon OSBB, but these are frowned upon by many inc Specialized who will not warranty the frame unless Spec cranks are fitted, the problem is the threaded outboard cups of the Campy/Fulcrum cranks(and others)are pretty much unsupported by the narrow bottom bracket shell.

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Ti or dye!

The Weenie formally known as CAADHEAD

Thanks for the detailed answer caadhead. Argon it is then!

I won't pretend to be an expert on this matter, my above post is just from reading a little into it, I'm happy to be corrected by anyone with personal experience on the matter? Always happy to help a fellow Welshman

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Ti or dye!

The Weenie formally known as CAADHEAD

My SL3 S-Works used a carbon OSBB. any BB30 compatible cranks work fine with OSBB. I'm using Zipp Vume Quads but cranks like Cannondale Hollowgram also work with no issues.



The SL3 you had did it have a threaded BB or OSBB?

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Isn't the OS BB just a different name for a Pressfit 30 on Specialized bikes. Seems strange for them to change it to a slimmer width.

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/jonas l
http://cerrol.wordpress.com (my cyclingblog)

OSBB does not equal pf30. pf30 is a 68mm frame with cups that hold the bearings in. the lips of the cups add width to the 68mm, which mostly affects people with siSL cranks or SRMs.
OSBB goes with a 61mm frame that holds the bearings. frame PLUS cups equals 68mm, equals BB30. the nice thing about the OSBB is that the bearings are very easy to get in n out, you reuse the cups and replace bearings when needed, etc etc. it's easier to work with, as long as you dont need to install a campy OS FIT cup.
currently, the best way i can see to mount a campy/fulcrum crank to a carbon OSBB frame is to use WheelsMfg's new adapter for Campy-to-bb30 (NOT Campy-to-pf30). the only annoying thing is that you use the bb30 bearings in the frame AND you keep the campy bearings on the crank. so you use four bearings, two are just along for the ride, even though the weight penalty is practically zero, it annoys me on principle.

http://www.specialized.com/media/whatsnew/CG0307_RevA.pdf
http://wheelsmfg.com/products/bottom-brackets-front-drivetrain/bb-adapters/bb30-adapter-for-campagnolo-cranks.html

Ah now thats the sort of response I was hoping for, somebody that knows their OSBB's

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Ti or dye!

The Weenie formally known as CAADHEAD

Great info. Guess I wont be buying the specialized! I don't get these BB's, I just want to ride. The argon gallium pro has a bb86 BB. Does that mean I will have the same problem again with ultra torque cranks or not?
Thanks
Rhys

Thanks for the lesson thisisatest. OSBB cups and then the frame is BB30 it seems like on the pdf

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/jonas l
http://cerrol.wordpress.com (my cyclingblog)

bb86 with campy- i must admit that is one ive never had to try. just pondering it for a minute, it doesnt seem complicated to make a bb86 "cup" that will take a slip-fit ultratorque crank and bearing. youd just need a little extra to have a ridge with two holes in it to fit campy's clip. that's probably also the only thing holding back someone from just bolting an ultratorque crank to a bb90 madon't. but this is just a ramble...

The Cbear setup is really the best. It uses machined aluminum and is stout. The issues come with people trying got run the Specialized plastic cups (which make the frame essentially BB30 width) and then put the Campy BB30 press in cup into that. That doesn't work well over the long run at all.

It's beyond me why Spec just didn't make the frame PF30. They have on their MTB.... it's a true PF30 BB.

So does that mean that any BB30 crankset e.g. SRAM Red will work in the frame without any 3rd party adaptors, which means i would be willing to sell my fulcrums and buy a BB30 crankset if it makes it a lot cleaner and work better?

Any BB30 crank will work. I've tried Campag cranks but no luck. I run S-works with Praxis rings works perfect I'm running 11sp.

Then why give information out you're not sure of?