I've recently bought a SL3 equipped with a OSBB and a Specialized Fact CT crankset. The latter has been removed, and I'm now trying to mount a Rotor 3D+ cranckset. The frame currently has some "C-bear BB30-46 Road" bearings press fitted into it. I've installed the two spacers (11.5mm) provided with the Rotor 3D+, but still, there's about 5mm of 'space' left to be filled. The crankset is also able to move in the bottom bracket if you push it. Anyone in the know what more I need ?

I used a normal pressfit 30 with my 3D+ crank and the two spacers. Does your BB come with the extra bearing shields that most Sram and Cannondale BB's come with (the red and green ones at this link: http://www.cannondaleexperts.com/assets ... /ka021.jpg ?

If not, get some of those. Again, Sram includes them with their BBs and most shops should have them. After that you will need to adjust the preload washer, but that should do it.

Thanks for replying, KWalker. There are indeed two plastings bearing shields provided by Rotor 3D+, but they can't make up for the space that's left.

Excuse my shallow knowledge of the English language, but what is a preload washer ? Google didn't help..

I think I might need the OSBB 62-86 C-Bear -as found on this overview http://www.c-bear.com/image/bbchart-print.pdf - instead of the C-Bear BB30-46 that's mounted right now. I'd still be interested to see what others are using though.

Rotor doesn't include these. You need these shields in addition to what they provide.

So the shields you posted (Cannondale image), are they at least 5mm in width ?

The SRAM bearing shields are 2.5mm in width IIRC.

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C-Bear makes two bottom brackets with 46-30 designations. One is a pure pf30, the other is for carbon osbb frames (which are 61mm wide as opposed to 68mm wide). You probably have the wrong one.
wheels mfg makes spacers that go between the cup and frame to space the bearings out to the proper width. this would be a reasonable option. Another route, my preference, would be to ditch the C-Bear bb and get some ROAD OSBB cups from a specialized dealer. If you want, you could pull the ceramic bearings out of the C-Bear cups and put them in the OSBB cups.
you could conceivably also add 3.5mm of spacers to the spindle on both sides of your current arrangement, but I wouldn't, as the bearings will be resting on an interior portion of spindle, not as intended and not designed to support the load.

Thanks so much for all the answers. I'll be weighing my options..

Thanks to your help and the input of fellow ww'er Pcrispey, the problem is almost completely solved now. I got some OSBB Road cups which were installed. The bearings from the C-Bear were removed and installed in the OSBB Road cups. There's still some free space left, but that can be left out by adjusting the screw on the Rotor 3D+ crank (non-drive side). Ideally, I should still install a bearing shield because the cranck screw seems stretched to the limit.

Yes in that system, bearing shields should be installed on both sides.
I apologize for not making that clear.

No problem! I appreciated your help. Does anyone know where to buy such bearing shields online ? A quick google search didn't provide much help

Where are you located? I have 2 Sram shields in my toolbox. PM me your address and if you're in the US I can send for free.